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Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2018	Feb. 15, 2019	Jun. 30, 2018
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Trading Symbol	MSCI
Entity Registrant Name	MSCI Inc.
Entity Central Index Key	0001408198
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		84,323,295
Entity Public Float			$ 14,368,769,114

Consolidated Statements of Financial Condition - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 904,176	$ 889,502
Accounts receivable (net of allowances of $1,027 and $1,700 at December 31, 2018 and December 31, 2017, respectively)	473,433	327,597
Prepaid income taxes	19,273	15,103
Prepaid and other assets	38,207	34,927
Total current assets	1,435,089	1,267,129
Property, equipment and leasehold improvements (net of accumulated depreciation and amortization of $185,505 and $171,280 at December 31, 2018 and December 31, 2017, respectively)	90,877	94,437
Goodwill	1,545,761	1,560,621
Intangible assets (net of accumulated amortization of $541,967 and $507,612 at December 31, 2018 and December 31, 2017, respectively)	280,803	321,836
Deferred tax assets	14,903	12,013
Other non-current assets	20,519	19,632
Total assets	3,387,952	3,275,668
Current liabilities:
Accounts payable	3,892	1,612
Income taxes payable	16,253	14,828
Accrued compensation and related benefits	137,045	131,156
Other accrued liabilities	113,841	85,710
Deferred revenue	537,977	374,365
Total current liabilities	809,008	607,671
Long-term debt	2,575,502	2,078,093
Deferred tax liabilities	82,008	78,027
Other non-current liabilities	87,928	110,865
Total liabilities	3,554,446	2,874,656
Commitments and Contingencies (see Note 5 and Note 9)
Shareholders' equity (deficit):
Preferred Stock (par value $0.01, 100,000,000 shares authorized, no shares issued)
Common stock (par value $0.01; 750,000,000 common shares authorized; 130,029,926 and 129,543,856 common shares issued and 84,174,138 and 90,104,885 common shares outstanding at December 31, 2018 and December 31, 2017, respectively)	1,300	1,295
Treasury shares, at cost (45,855,788 and 39,438,971 common shares held at December 31, 2018 and December 31, 2017, respectively)	(3,272,774)	(2,321,989)
Additional paid in capital	1,306,428	1,264,849
Retained earnings	1,856,951	1,505,204
Accumulated other comprehensive loss	(58,399)	(48,347)
Total shareholders' equity (deficit)	(166,494)	401,012
Total liabilities and shareholders' equity (deficit)	$ 3,387,952	$ 3,275,668

Consolidated Statements of Financial Condition (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Statement Of Financial Position [Abstract]
Accounts receivable, allowances	$ 1,027	$ 1,700
Property, equipment and leasehold improvements, accumulated depreciation and amortization	185,505	171,280
Intangible assets, accumulated amortization	$ 541,967	$ 507,612
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	100,000,000	100,000,000
Preferred stock, shares issued	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	750,000,000	750,000,000
Common stock, shares issued	130,029,926	129,543,856
Common stock, shares outstanding	84,174,138	90,104,885
Treasury shares	45,855,788	39,438,971

Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Operating revenues	$ 361,688	$ 357,934	$ 363,046	$ 351,316	$ 334,779	$ 322,097	$ 316,089	$ 301,207	$ 1,433,984	$ 1,274,172	$ 1,150,669
Operating expenses:
Cost of revenues	73,757	70,906	71,368	71,304	69,247	68,433	68,538	67,463	287,335	273,681	252,107
Selling and marketing	52,949	46,149	47,416	46,409	47,726	44,873	41,550	42,972	192,923	177,121	166,666
Research and development	20,312	20,591	19,801	20,707	20,709	17,974	18,196	18,970	81,411	75,849	75,204
General and administrative	24,908	24,751	24,036	26,187	23,280	22,079	21,424	20,981	99,882	87,764	87,235
Amortization of intangible assets	11,633	11,681	19,537	11,338	11,560	10,614	11,122	11,251	54,189	44,547	47,033
Depreciation and amortization of property, equipment and leasehold improvements	8,311	7,453	7,377	8,205	8,118	9,325	9,159	8,838	31,346	35,440	34,320
Total operating expenses	191,870	181,531	189,535	184,150	180,640	173,298	169,989	170,475	747,086	694,402	662,565
Operating income	169,818	176,403	173,511	167,166	154,139	148,799	146,100	130,732	686,898	579,770	488,104
Interest income	(6,096)	(6,522)	(4,281)	(2,770)	(2,237)	(1,835)	(1,310)	(932)	(19,669)	(6,314)	(2,906)
Interest expense	35,891	35,902	31,761	29,560	29,027	29,020	29,027	29,024	133,114	116,098	101,651
Other expense (income)	(47,266)	177	(10,292)	938	389	811	872	1,015	(56,443)	3,087	3,421
Other expense (income), net	(17,471)	29,557	17,188	27,728	27,179	27,996	28,589	29,107	57,002	112,871	102,166
Income before provision for income taxes	187,289	146,846	156,323	139,438	126,960	120,803	117,511	101,625	629,896	466,899	385,938
Provision for income taxes	35,157	23,014	39,494	24,346	62,358	35,650	36,245	28,674	122,011	162,927	125,083
Net income	$ 152,132	$ 123,832	$ 116,829	$ 115,092	$ 64,602	$ 85,153	$ 81,266	$ 72,951	$ 507,885	$ 303,972	$ 260,855
Earnings per basic common share	$ 1.75	$ 1.39	$ 1.31	$ 1.28	$ 0.72	$ 0.94	$ 0.90	$ 0.80	$ 5.83	$ 3.36	$ 2.72
Earnings per diluted common share	$ 1.70	$ 1.36	$ 1.28	$ 1.24	$ 0.70	$ 0.93	$ 0.89	$ 0.80	$ 5.66	$ 3.31	$ 2.70
Weighted average shares outstanding used in computing earnings per share:
Basic	86,968	88,796	89,112	90,075	90,130	90,112	90,404	90,708	87,179	90,336	95,986
Diluted	89,495	91,372	91,586	92,587	92,467	91,868	91,708	91,624	89,701	91,914	96,540

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 507,885	$ 303,972	$ 260,855
Other comprehensive income (loss):
Foreign currency translation adjustments	(14,113)	13,358	(24,871)
Income tax effect			(714)
Foreign currency translation adjustments, net	(14,113)	13,358	(25,585)
Pension and other post-retirement adjustments	2,351	(525)	660
Income tax effect	(227)	(445)	(65)
Pension and other post-retirement adjustments, net	2,124	(970)	595
Net investment hedge adjustments	1,937
Net investment hedge adjustments, net	1,937
Other comprehensive (loss) income, net of tax	(10,052)	12,388	(24,990)
Comprehensive income	$ 497,833	$ 316,360	$ 235,865

Consolidated Statements of Shareholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Balance at Dec. 31, 2015	$ 901,487	$ 1,282	$ (1,395,695)	$ 1,173,183	$ 1,158,462	$ (35,745)
Net income	260,855				260,855
Dividends	(97,059)			34	(97,093)
Other comprehensive income (loss), net of tax	(24,990)					(24,990)
Common stock issued	5	5
Compensation payable in common stock and options	39,648			39,648
Common stock repurchased and held in treasury	(774,565)		(774,565)
Common stock issued to directors and held in treasury	(441)		(479)	38
Exercise of stock options	5,040	3		5,037
Excess tax benefits from employee stock incentive plans	7,625			7,625
Balance at Dec. 31, 2016	317,605	1,290	(2,170,739)	1,225,565	1,322,224	(60,735)
Net income	303,972				303,972
Dividends	(120,972)			20	(120,992)
Other comprehensive income (loss), net of tax	12,388					12,388
Common stock issued	4	4
Compensation payable in common stock and options	36,572			36,572
Common stock repurchased and held in treasury	(150,461)		(150,461)
Common stock issued to directors and held in treasury	(731)		(789)	58
Exercise of stock options	2,635	1		2,634
Balance at Dec. 31, 2017	401,012	1,295	(2,321,989)	1,264,849	1,505,204	(48,347)
Net income	507,885				507,885
ASC Topic 606 Retained Earnings Adjustment \| Accounting Standards Update 2014-09 [Member]	16,135				16,135
Dividends	(172,231)		(77)	119	(172,273)
Other comprehensive income (loss), net of tax	(10,052)					(10,052)
Common stock issued	5	5
Compensation payable in common stock and options	40,838			40,838
Common stock repurchased and held in treasury	(949,888)		(949,888)
Common stock issued to directors and held in treasury	(803)		(820)	17
Exercise of stock options	605			605
Balance at Dec. 31, 2018	$ (166,494)	$ 1,300	$ (3,272,774)	$ 1,306,428	$ 1,856,951	$ (58,399)

Consolidated Statements of Shareholders' Equity (Deficit) (Parenthetical) - $ / shares	3 Months Ended												12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement Of Stockholders Equity [Abstract]
Dividends per common share	$ 0.58	$ 0.58	$ 0.38	$ 0.38	$ 0.38	$ 0.38	$ 0.28	$ 0.28	$ 0.28	$ 0.28	$ 0.22	$ 0.22	$ 1.92	$ 1.32	$ 1.00

Consolidated Statements of Cash Flows
$ in Thousands

12 Months Ended

Dec. 31, 2018

USD ($)

Dec. 31, 2017

USD ($)

Dec. 31, 2016

USD ($)

Cash flows from operating activities

Net income

$ 507,885

$ 303,972

$ 260,855

Adjustments to reconcile net income to net cash provided by operating activities:

Amortization of intangible assets

54,189

44,547

47,033

Stock-based compensation expense

38,897

36,576

32,001

Depreciation and amortization of property, equipment and leasehold improvements

31,346

35,440

34,320

Amortization of debt origination fees

3,715

3,396

3,068

Deferred taxes

(780)

(18,902)

(16,967)

Gain on divestitures, net of costs

(61,402)

(449)

Other non-cash adjustments

(188)

704

1,192

Changes in assets and liabilities, net of the effect of acquisitions and dispositions:

Accounts receivable

(153,942)

(105,593)

(18,494)

Prepaid income taxes

(4,069)

(3,069)

41,332

Prepaid and other assets

(2,015)

(4,470)

624

Accounts payable

2,300

1,027

(1,912)

Accrued compensation and related benefits

8,532

8,659

13,089

Income taxes payable

(2,890)

Other accrued liabilities

29,096

15,933

19,741

Deferred revenue

185,077

38,555

21,809

Other

(22,989)

47,383

^[1]

5,121

Net cash provided by operating activities

612,762

404,158

442,363

Cash flows from investing activities

Proceeds from sales of investments

771

Proceeds from divestitures

83,825

657

Proceeds from the sale of capital equipment

Capital expenditures

(30,257)

(33,177)

(32,284)

Capitalized software development costs

(18,704)

(15,640)

(10,344)

Acquisitions, net of cash acquired

(60)

Net cash provided by (used in) investing activities

34,874

(48,046)

(42,031)

Cash flows from financing activities

Proceeds from borrowing

500,000

Proceeds from exercise of stock options

605

2,635

5,040

Repurchase of common stock held in treasury

(949,888)

(150,461)

(774,565)

Payment of dividends

(170,938)

(119,717)

(96,191)

Payment of debt issuance costs in connection with debt

(6,262)

(7,183)

Net cash used in financing activities

(626,483)

(267,543)

(372,899)

Effect of exchange rate changes

(6,479)

9,099

(13,305)

Net increase in cash

14,674

97,668

14,128

Cash and cash equivalents, beginning of period

889,502

791,834

777,706

Cash and cash equivalents, end of period

904,176

889,502

791,834

Supplemental disclosure of cash flow information:

Cash paid for interest

125,986

112,502

89,139

Cash paid for income taxes

143,215

128,727

97,845

Supplemental disclosure of non-cash investing activities

Property, equipment and leasehold improvements in other accrued liabilities

2,999

4,588

4,422

Supplemental disclosure of non-cash financing activities

Cash dividends declared, but not yet paid

$ 862

$ 1,197

$ 830

[1]	Includes $43.6 million accrual for amounts payable after December 31, 2018 related to the estimated one-time tax charge on the deemed repatriation of historic earnings and profits of foreign subsidiaries. See Note 11, “Income Taxes,” for additional information.

Consolidated Statements of Cash Flows (Parenthetical) $ in Millions	Dec. 31, 2018 USD ($)
Statement Of Cash Flows [Abstract]
Accrued amount payable	$ 43.6

Introduction and Basis of Presentation

12 Months Ended

Dec. 31, 2018

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Introduction and Basis of Presentation

1. INTRODUCTION AND BASIS OF PRESENTATION

Organization

MSCI Inc., together with its wholly-owned subsidiaries (the “Company” or “MSCI”) provides mission critical investment decision support tools and services. MSCI is dynamic and flexible in the delivery of content and capabilities, such as indexes; portfolio construction tools and risk-management services; environmental, social and governance (“ESG”) research and ratings; and real estate benchmarks, return analytics services and market insights; much of which can be accessed by clients through multiple channels and platforms.

Basis of Presentation

The consolidated financial statements include the accounts of MSCI Inc. and its wholly-owned subsidiaries. The Company’s policy is to consolidate all entities in which it owns more than 50% of the outstanding voting stock unless it does not control the entity. It is also the Company’s policy to consolidate any variable interest entity for which the Company is the primary beneficiary, as required by the Financial Accounting Standards Board’s (“FASB”) Accounting Standards Codification (“ASC”) Subtopic 810-10, “Consolidations.” As of December 31, 2018, the Company had no such variable interest entities or investments.

The Company’s operating expenses are grouped and presented in the following activity categories: cost of revenues, selling and marketing, research and development and general and administrative. Costs are assigned to these activity categories based on the nature of the expense to which they directly relate, or, when not directly attributable, based on an allocation method that considers the type of effort related to such activities.

Cost of revenues consists of costs related to the production and servicing of the Company’s products and services and primarily includes related information technology costs, including data center, platform and infrastructure costs; costs to acquire, produce and maintain market data information; costs of research to support and maintain existing products; costs of product management teams; costs of client service and consultant teams to support customer needs; as well as other support costs directly attributable to the cost of revenues including certain human resources, finance and legal costs.

Selling and marketing expenses consist of costs associated with acquiring new clients or selling new products or product renewals to existing clients and primarily includes the costs of MSCI’s sales force and marketing teams as well as costs incurred in other groups associated with acquiring new business, including product management, research, technology and sales operations.

Research and development expenses consist of costs to develop new or enhance existing products and the costs to develop new or improved technology and service platforms for the delivery of MSCI’s products and services and primarily includes the costs of development, research, product management, project management and the technology support associated with these efforts.

General and administrative expenses consist of costs primarily related to finance operations, human resources, office of the CEO, legal, corporate technology, corporate development and certain other administrative costs that are not directly attributed, but are instead allocated, to a product or service.

Certain prior period amounts have been reclassified to conform to the current period presentation.

Significant Accounting Policies

Basis of Financial Statements and Use of Estimates

The Company’s consolidated financial statements are prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”). These accounting principles require the Company to make certain estimates and judgments that can affect the reported amounts of assets and liabilities as of the date of the consolidated financial statements, as well as the reported amounts of revenue and expenses during the periods presented. Significant estimates and assumptions made by management include the deferral and recognition of revenue, research and development and software capitalization, impairment of long-lived assets, accrued compensation, income taxes and other matters that affect the consolidated financial statements and related disclosures. The Company believes that estimates used in the preparation of these consolidated financial statements are reasonable; however, actual results could differ materially from these estimates.

Inter-company balances and transactions are eliminated in consolidation.

Revenue Recognition

MSCI adopted the new revenue standard set forth under Accounting Standards Codification Topic 606 “Revenue from Contracts with Customers,” or ASC Topic 606, as of January 1, 2018 using the Modified Retrospective Approach and as such, applied the new revenue standard only to contracts that were not completed at the January 1, 2018 adoption date and did not adjust prior reporting periods. An adjustment was recorded within the Consolidated Statement of Financial Condition as of January 1, 2018. The adoption resulted in more revenue being recognized upfront or earlier in the life of new client contracts for certain of the Company’s products and services, including fees related to the licensing of certain desktop applications as they relate to the energy and commodity analytics products, implementation services as they relate to Analytics products and services and the Company’s hosted applications and set-up fees as they relate to the Company’s custom index products. The new revenue standard also has the impact of ratably allocating revenue recognition as it relates to multi-year deals. The adoption of the standard also resulted in higher accounts receivable and deferred revenue balances. Under the old revenue standard, MSCI generally recorded the value of an invoice to accounts receivable and deferred revenue once the service period began. Under the new revenue standard, MSCI records accounts receivable and a corresponding offset to deferred revenue when an invoice is issued. See Note 3, “Revenue Recognition,” for further discussion of the impact of the change upon adoption of ASC Topic 606.

Performance Obligations and Transaction Price

For revenue arrangements containing multiple products or services, the Company accounts for the individual products or services as a separate performance obligation if they are distinct, the product or service is separately identifiable from other items in the arrangement, and if a client can benefit from it on its own or with other resources that are readily available to the client. If these criteria are not met, the promised products or services are accounted for as a combined performance obligation.

The Company allocates the transaction price to each performance obligation based on the best estimate of the relative standalone selling price of each distinct product or service in the contract. The transaction price in the contract is allocated at contract inception to the distinct product or service underlying each performance obligation in proportion to the standalone selling prices. This standalone selling price may be the contract price, but is more often than not the best estimate of the price the Company would receive for selling the product or service to other similar customers. Discounts applied to the contract will be allocated based on the same proportion of standalone selling prices.

For services where the transaction price is variable based upon assets under management (“AUM”), volume of trades or number of investments linked to MSCI’s indexes, the transaction price is based upon pricing models and is not allocated at the inception of the contract but rather falls within the sales and usage-based royalty exception under which the price and associated revenue are based upon actual known performance or best estimates of actual performance during the performance period.

Revenue is recognized when a customer obtains control of promised products or services in an amount that reflects the consideration the entity expects to receive in exchange for those products or services. Revenue is recognized exclusive of any applicable sales or other indirect taxes. Determining when control has transferred can sometimes require management’s judgement (e.g., implementation services), which could affect the timing of revenue recognition. The Company has determined that the above methods provide a faithful depiction of the transfer of control of products or services to the customer.

Disaggregation of Revenue

Our revenues are characterized by type, which broadly reflects the nature of how they are recognized or earned. Our revenue types are recurring subscription, asset-based fees and non-recurring revenues. We also group our revenues by segment.

Revenues By Type

Recurring subscription revenues represent fees earned from clients primarily under renewable contracts or agreements and are generally paid annually or quarterly in advance and recognized in most cases ratably over the term of the license or service pursuant to the contract terms. Revenues from subscription agreements for the receipt of periodic benchmark reports, digests and other publications, which are most often associated with our real estate offerings, are generally billed and recognized upon delivery of such reports or data updates.

Asset-based fees are principally recognized based on the estimated AUM linked to our indexes from independent third-party sources or the most recently reported information provided by the client. Asset-based fees also include revenues related to futures and options contracts linked to our indexes, which are primarily based on trading volumes. Asset-based fees are generally variable based upon AUM or the volume of trades and are generally billed quarterly in arrears.

Non-recurring revenues primarily represent fees earned on products and services where we do not have renewal contracts and primarily include revenues for providing customized reports, historical data sets, certain derivative financial products and certain implementation and consulting services, as well as revenues from particular products and services that are purchased on a non-renewal basis. Based on the nature of the services provided, non-recurring revenues are generally billed upon delivery and recognized upon delivery or over the service period.

Revenues By Segment

For products within the Index segment, with respect to index data subscriptions, MSCI’s performance obligation to deliver the data is satisfied over time and, accordingly, revenue is recognized ratably over the term of the agreement pursuant to the contract terms. With respect to licenses to create index-linked investment products, such as ETFs, passively managed funds, or licenses which allow certain exchanges to use MSCI’s indexes as the basis for futures and options contracts, MSCI’s performance obligation allows customers to use the Company’s intellectual property (e.g., the indexes) as the basis of the funds or other investment products the customers create over the term of the agreement. The fees earned for these rights are typically variable, in which case they are accrued under the sales and usage-based royalty exception pursuant to the level of performance achieved, which is measured based on AUM, volume of trades or other factors. The level of performance achieved is based on information obtained from independent third-party sources or best estimates taking into account the most recently reported information from the client.

For products within the Analytics segment, MSCI’s performance obligations include providing access to its proprietary models or hosted applications and, in some cases, delivery of managed services, which are all satisfied over time, and accordingly, revenue is recognized ratably over the term of the service period. For implementation services, MSCI meets its performance obligation once the implementation service is complete and the related service is available for the client to use and revenue is recognized at the point in time when the implementation service is completed.

For products within the All Other segment, MSCI’s performance obligations under its ESG products are satisfied over time for the majority of the data subscriptions as MSCI provides and updates the data to the customer throughout the term of the agreement and revenue is recognized ratably over the term of the agreement. For custom ESG research data, the performance obligation is complete, and revenue is recognized, at the point in time that the data is updated and available to the customer. MSCI’s Real Estate products primarily include periodic benchmark reports, Market Information and other publications. MSCI primarily satisfies its performance obligations, and revenue is recognized, at the point in time when the Company delivers reports or publications. For Market Information products, publications are delivered throughout the year, and the revenue is recognized over time.

Share-Based Compensation

Certain of the Company’s employees have received share-based compensation under various compensation programs. The Company’s compensation expense reflects the fair value method of accounting for share-based payments under ASC Subtopic 718-10, “Compensation—Stock Compensation.” ASC Subtopic 718-10 requires measurement of compensation cost for equity-based awards at fair value and recognition of compensation cost over the service period, net of estimated forfeitures.

The fair value of MSCI restricted stock units (“RSUs”) is measured using the closing price of MSCI’s common stock on the date prior to grant. Restricted stock units subject to performance conditions that are not linked to a market condition (“PSUs”) are based on performance measures that impact the amount of shares that each recipient will receive upon vesting. The fair value of PSUs is measured using the closing price of MSCI’s common stock on the date prior to grant. Restricted stock units that are subject to the achievement of multi-year total shareholder return targets (“MSUs”) are performance awards with a market condition. The fair value of MSUs is determined using a Monte Carlo simulation model that creates a normal distribution of future stock prices, which is then used to value the awards based on their individual terms.

The fair value of MSCI standard stock options is determined using the Black-Scholes valuation model and the single grant life method. Under the single grant life method, option awards with graded vesting are valued using a single weighted-average expected option life. The fair value of MSCI stock options that contain stock price contingencies is determined using a Monte Carlo simulation model.

The Company recognizes the expense for an award granted to an employee who is not retirement-eligible utilizing the graded vesting method over the requisite service period. For all awards, the Company bases initial accruals of compensation cost on the estimated number of units for which the requisite service is expected to be rendered and, for PSUs, the performance targets expected to be achieved is also considered. If the estimated number of units or the number of units ultimately delivered changes from previous estimates, the cumulative effect on current and prior periods of a change is recognized in compensation cost in the period of the change. Because the probability of actual shares expected to be earned is reflected in the fair value of MSUs on the grant date, the expense to be recognized for these awards is not adjusted to reflect the actual shares earned.

Based on interpretive guidance related to share-based compensation, the Company’s policy is to accrue the estimated cost of share-based awards that are granted to retirement-eligible employees over the course of the prior year in which they were earned rather than expensing the awards on the date of grant. A portion of the awards granted to retirement-eligible employees consisted of PSUs. For those PSUs, the Company bases initial accruals of compensation cost on the estimated number of units for which the requisite service is expected to be rendered. If the estimated number of units expected to convert changes from previous estimates based on the performance targets expected to be achieved, the cumulative effect of a change is recognized in compensation cost in the period of the change.

Research and Development

The Company accounts for research and development costs in accordance with several accounting pronouncements, including ASC Subtopic 730-10, “Research and Development.” ASC Subtopic 730-10 requires that research and development costs generally be expensed as incurred. The majority of the Company’s research and development costs are incurred in developing, reviewing and enhancing the methodologies and data models offered within its product portfolio by monitoring investment trends and drivers globally, as well as analyzing product-specific needs in areas such as capitalization-weighted, factor and specialized indexes, and instrument valuation, risk modeling, portfolio construction, asset allocation and value-at-risk simulation.

The Company applies the provisions of ASC Subtopic 350-40, “Internal Use Software,” and accounts for the cost of computer software developed for internal use by capitalizing qualifying costs, which are substantially incurred during the application development stage. The amounts capitalized are included in Intangible Assets on the Consolidated Statement of Financial Condition and include external direct costs of services used in developing internal-use software and payroll and payroll-related costs of employees directly associated with the development activities. Additionally, costs incurred relating to upgrades and enhancements to the software are capitalized if it is determined that these upgrades or enhancements provide additional functionality to the software.

During the years ended December 31, 2018 and 2017, the Company capitalized $18.7 million and $15.6 million, respectively, of costs related to software developed for internal use in the Consolidated Statement of Financial Condition.

Capitalized software development costs are amortized on a straight-line basis over the estimated useful life of the related product, which is typically three to five years, beginning with the date the software is placed into service.

Costs incurred in the preliminary and post-implementation stages of MSCI’s products are expensed as incurred.

Income Taxes

Provision for income taxes is provided for using the asset and liability method, under which deferred tax assets and deferred tax liabilities are determined based on the temporary differences between the financial statement and income tax bases of assets and liabilities using currently enacted tax rates. The Company elects to account for Global Intangible Low-Taxed Income (“GILTI”) in the year the tax is incurred. The Company recognizes interest and penalties related to income tax matters within “Provision for income taxes” in the Consolidated Statement of Income.

The Company regularly evaluates the likelihood of additional assessments in each of the taxing jurisdictions in which it is required to file income tax returns. The Company has recorded additional tax expense related to open tax years, which the Company’s management believes is adequate in relation to the potential for assessments. These amounts have been recorded in “Other non-current liabilities” on the Consolidated Statement of Financial Condition. The Company’s management believes the resolution of tax matters will not have a material effect on the Company’s consolidated financial condition. However, to the extent the Company is required to pay amounts in excess of its reserves, a resolution could have a material impact on its Consolidated Statement of Income for a particular future period. In addition, an unfavorable tax settlement could require use of cash and result in an increase in the effective tax rate in the period in which such resolution occurs.

Deferred Revenue

Deferred revenues represent both cash received and/or the amounts billed to customers for products and services in advance of services being provided and before the service period has begun. Deferred revenue is generally amortized ratably over the service period as the performance obligations are satisfied.

Accounts Receivable

The Company’s clients generally pay subscription fees annually or quarterly in advance. MSCI’s policy is to record to a receivable when a customer is billed. For products and services that are provided in advance of billing, such as for our asset-based fee products, unbilled revenue (or a “contract asset”) is included in Accounts Receivable on the Company’s Consolidated Statement of Financial Condition.

Goodwill

Goodwill is recorded as part of the Company’s acquisitions of businesses when the purchase price exceeds the fair value of the net tangible and separately identifiable intangible assets acquired. The Company’s goodwill is not amortized, but rather is subject to an impairment test each year, or more often if conditions indicate impairment may have occurred, pursuant to ASC Subtopic 350-10, “Intangibles—Goodwill and Other.”

The Company tests goodwill for impairment on an annual basis on July 1 and on an interim basis when certain events and circumstances exist. The testing for impairment is performed at the reporting unit level. Goodwill impairment is determined by comparing the fair value of a reporting unit with its carrying value. If the estimated fair value exceeds the carrying value, goodwill at the reporting unit level is not deemed to be impaired. If the estimated fair value is below carrying value, however, further analysis is required to determine the amount of impairment, if any. If necessary, an impairment charge will be recorded up to, but not more than, the total amount of goodwill allocated to the reporting unit.

The Company completed its annual goodwill impairment test as of July 1, 2018 on its four reporting units, which are the same as its four operating segments. The Company performed a step zero, qualitative impairment test on each of its operating segments and determined that it was more likely than not that the fair value for each operating segment was not less than the carrying value for each.

As the estimated fair value of the Company’s reporting units exceeded their carrying value on the testing dates, no impairment of goodwill was recorded during the years ended December 31, 2018, 2017 and 2016.

Intangible Assets

The Company amortizes definite-lived intangible assets over their estimated useful lives. Definite-lived intangible assets are reviewed for impairment whenever events or changes in circumstances indicate that the carrying value of the asset may not be recoverable. The Company also reviews the useful lives on a quarterly basis to determine if the period of economic benefit has changed. If the carrying value of an intangible asset exceeds its fair value, an impairment charge would be recognized in an amount equal to the amount by which the carrying value of the intangible asset exceeds its fair value.

During the year ended December 31, 2018, management decided to discontinue the use of the IPD tradename utilized by the Real Estate segment and has rebranded the segment to MSCI Real Estate. As a result, the remaining unamortized value of $7.9 million was written off.

The Company had no indefinite-lived intangible assets.

Foreign Currency Translation

Assets and liabilities of operations having non-U.S. dollar functional currencies are translated at year-end exchange rates, and income statement accounts are translated at weighted average exchange rates for the year. Gains or losses resulting from translating foreign currency financial statements, net of any related tax effects, are reflected in accumulated other comprehensive loss, a separate component of shareholders’ equity (deficit). Gains or losses resulting from foreign currency transactions incurred in currencies other than the local functional currency are included in non-operating “Other expense (income)” on the Consolidated Statement of Income.

Derivative Instruments

The Company applies ASC Subtopic 815-10, “Derivatives and Hedging,” which establishes accounting and reporting standards for derivative instruments and hedging activities. The Company may use interest rate swaps and forward contracts on foreign currency to manage risks generally associated with interest rate and foreign exchange rate fluctuations, respectively. The Company’s derivative financial instruments are used as risk management tools and not for speculative or trading purposes.

For derivative instruments that are designated and qualify as hedging instruments for accounting purposes, the Company documents and links the relationships between the hedging instruments and hedged items. The Company also assesses and documents at the hedge’s inception whether the derivatives used in hedging transactions were effective in offsetting changes in fair values associated with the hedged items. ASC Subtopic 815-10 provides that, for derivative instruments that qualify for hedge accounting being used to hedge cash flows, changes in the fair value are recognized in accumulated other comprehensive income (loss), a separate component of shareholders’ equity, until the hedged item is recognized in earnings. In addition, the ineffective portion of a derivative’s change in fair value is immediately recognized in earnings.

The Company manages foreign currency exchange rate risk through the use of derivative financial instruments comprised principally of forward contracts on foreign currency which are not designated as hedging instruments for accounting purposes. The objective of the derivative instruments is to minimize the income statement impact associated with assets and liabilities that are denominated in certain foreign currencies. Derivative instruments that do not qualify for hedge accounting are carried at fair value on the Consolidated Statement of Financial Condition with gains and losses recorded in the Consolidated Statement of Income in the period in which they are realized.

Property, Equipment and Leasehold Improvements

Property, equipment and leasehold improvements are stated at cost less accumulated depreciation and amortization. Depreciation of furniture and fixtures, computer and communications equipment and leasehold improvements are amortized using the straight-line method over the estimated useful life of the asset.

Treasury Stock

The Company holds repurchased shares of common stock as treasury stock. The Company accounts for treasury stock under the cost method and includes treasury stock as a component of shareholders’ equity (deficit).

Allowance for Doubtful Accounts

The Company periodically reviews receivable balances and maintains an allowance on customer accounts where estimated losses may result from the inability of its customers to make required payments. The Company does not require collateral.

An allowance for doubtful accounts is recorded when it is probable and estimable that a receivable will not be collected. Changes in the allowance for doubtful accounts from December 31, 2015 to December 31, 2018 were as follows:

	Amount
	(in thousands)
Balance as of December 31, 2015	$	1,117
Addition to provision		1,011
Amounts written off, net of recoveries		(1,093	)
Balance as of December 31, 2016	$	1,035
Addition to provision		1,422
Amounts written off, net of recoveries		(757	)
Balance as of December 31, 2017	$	1,700
Reduction to provision		(224	)
Amounts written off, net of recoveries		(449	)
Balance as of December 31, 2018	$	1,027

Accrued Compensation

The Company makes significant estimates in determining its accrued non-stock-based compensation and benefits expenses. A significant portion of the Company’s employee incentive compensation programs are discretionary. At the end of each fiscal year, the Company determines the amount of discretionary cash bonus expense. These estimates reflect an assessment of performance versus targets and other key performance indicators at the Company, operating segment and employee level. The Company also reviews compensation and benefits expenses throughout the year to determine how overall performance compares to management’s expectations. These and other factors, including historical performance, are taken into account in accruing discretionary cash compensation estimates quarterly.

Concentrations

For the years ended December 31, 2018 and 2017, BlackRock, Inc. accounted for 11.9% and 11.5%, respectively, of the Company’s consolidated operating revenues while no single customer represented 10.0% or more of the Company’s consolidated operating revenues for the year ended December 31, 2016. For the years ended December 31, 2018, 2017 and 2016, BlackRock, Inc. accounted for 20.1%, 20.0% and 17.3%, respectively, of the Index segment’s operating revenues. No single customer accounted for 10.0% or more of operating revenues within the Analytics and All Other segments for the years ended December 31, 2018, 2017 and 2016.

Recent Accounting Standards Updates

12 Months Ended

Dec. 31, 2018

Accounting Changes And Error Corrections [Abstract]

Recent Accounting Standards Updates

2. RECENT ACCOUNTING STANDARDS UPDATES

In February 2016, the FASB issued Accounting Standards Update No. 2016-02, “Leases (Topic 842),” or ASU 2016-02. The FASB issued ASU 2016-02 in order to increase transparency and comparability among organizations by recognizing lease assets and liabilities on the balance sheet and disclosing key information about leasing arrangements. To meet that objective, the FASB amended the FASB Accounting Standards Codification and created Topic 842, Leases. ASU 2016-02 is effective for annual reporting periods, including interim periods within those periods, beginning after December 15, 2018.

In July 2018, the FASB issued Accounting Standards Update No. 2018-10, “Codification Improvements to Topic 842, Leases,” or ASU 2018-10, and Accounting Standards Update No. 2018-11, “Targeted Improvements,” or ASU 2018-11. The amendments in ASU 2018-10 include how an entity should perform the lease classification reassessment, a clarification that a change in a reference index or rate upon which some or all of the variable lease payments in the contract are based does not constitute the resolution of a contingency and a clarification as to whether to recognize a transition adjustment in earnings rather than through equity when an entity initially applies Topic 842 retrospectively to each prior reporting period. The amendments in ASU 2018-11 provide an optional transition method that permits an entity to initially apply the new guidance at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption and not recast comparative periods. As a result, prior period financial statements and disclosures will continue to be presented in accordance with ASC Topic 840. In addition, ASU 2018-11 also includes a practical expedient for lessors to not separate the lease and non-lease components of a contract. The effective date for this amendment is the same as ASU 2016-02 discussed above.

The Company will be adopting ASU 2016-02 effective January 1, 2019 using the optional transition method available under ASU 2018-11. In preparation for adoption of the guidance, the Company is implementing internal controls and key system functionality to enable the preparation of financial information. MSCI will take advantage of the transition package of practical expedients permitted within the new guidance which, among other things, will allow the Company to carryforward the historical lease classification. In addition, MSCI will elect the hindsight practical expedient to determine the reasonably certain lease term for existing leases. The Company will make an accounting policy election that will keep leases with an initial term of 12 months or less off of the Consolidated Statement of Financial Condition and will result in recognizing those lease payments in the Consolidated Statement of Income on a straight-line basis over the lease term.

While the Company is continuing to assess all potential impacts of the guidance, the guidance will have a material impact on the Consolidated Statement of Financial Condition but will not have a material impact on the Consolidated Statement of Income or Consolidated Statement of Cash Flows. The most significant impact will be the recognition of right-of-use (“ROU”) assets and lease liabilities for operating leases. Adoption of the guidance will result in the recognition and presentation of total operating lease ROU assets estimated to be approximately $170.0 million to $190.0 million and total operating lease liabilities estimated to be approximately $190.0 million to $210.0 million, both as of January 1, 2019.

MSCI does not believe the new guidance will have a material impact on its liquidity and under its current agreements it will have no impact on its debt-covenant compliance.

In June 2016, the FASB issued Accounting Standards Update No. 2016-13, “Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments,” or ASU 2016-13. The amendments in ASU 2016-13 introduce an approach based on expected losses to estimate credit losses on certain types of financial instruments, modify the impairment model for available-for-sale debt securities and provide for a simplified accounting model for purchased financial assets with credit deterioration since their origination. ASU 2016-13 is effective for annual reporting periods, including interim periods within those periods, beginning after December 15, 2019, with early adoption permitted beginning after December 15, 2018. The adoption of ASU 2016-13 is not expected to have a material effect on the Company’s consolidated financial statements.

In January 2017, the FASB issued Accounting Standards Update No. 2017-01, “Business Combinations (Topic 805): Clarifying the Definition of a Business,” or ASU 2017-01. The amendments in ASU 2017-01 provide a screen to assist entities with evaluating whether transactions should be accounted for as acquisitions or disposals of assets or businesses. Under ASU 2017-01, an entity first determines whether substantially all of the fair value of the gross assets acquired is concentrated in a single identifiable asset or a group of similar identifiable assets. If this threshold is met, the set is not a business. If it is not met, the entity then evaluates whether the set meets the requirement that a business include, at a minimum, an input and a substantive process that together significantly contribute to the ability to create outputs. ASU 2017-01 also narrows the definition of outputs by more closely aligning it with how outputs are described in ASC Topic 606. The adoption of ASU 2017-01 did not have a material effect on the Company’s consolidated financial statements.

In January 2017, the FASB issued Accounting Standards Update No. 2017-04, “Intangibles-Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment,” or ASU 2017-04. The amendments in ASU 2017-04 simplify the subsequent measurement of goodwill by eliminating Step 2 from the goodwill impairment test. In computing the implied fair value of goodwill under Step 2, an entity had to perform procedures to determine the fair value at the impairment testing date of its assets and liabilities. Instead, under the amendments in ASU 2017-04, an entity performs its annual, or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount and recognizes an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value, but not more than the total amount of goodwill allocated to the reporting unit. ASU 2017-04 is effective for annual reporting periods, including interim periods within those periods, beginning after December 15, 2019, with early adoption permitted. The adoption of ASU 2017-04 is not expected to have a material effect on the Company’s consolidated financial statements.

In February 2017, the FASB issued Accounting Standards Update No. 2017-07, “Compensation—Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost,” or ASU 2017-07. The FASB issued ASU 2017-07 in order to improve the presentation of net periodic pension cost and net periodic postretirement benefit cost. ASU 2017-07 is effective for annual reporting periods, including interim periods within those periods, beginning after December 15, 2017. Entities should apply these amendments retrospectively for the presentation of the service cost component and the other components of net periodic pension cost and net periodic postretirement benefit cost in the income statement and prospectively, on and after the effective date, for the capitalization of the service cost component of net periodic pension cost and net periodic postretirement benefit in assets. As a result of the adoption of ASU 2017-07, the Company has restated the Consolidated Statement of Income for the year ended December 31, 2017 by reclassifying $0.6 million of non-service related pension costs from “Operating Expenses” to “Other expense (income).”

In May 2017, the FASB issued Accounting Standards Update No. 2017-09, “Compensation—Stock Compensation (Topic 718), Scope of Modification Accounting,” or ASU 2017-09. The FASB issued ASU 2017-09 in order to reduce the diversity in practice, as well as the cost and complexity when applying the guidance in Topic 718, “Compensation—Stock Compensation,” to a change to the terms or conditions of a share-based payment award. The amendments in ASU 2017-09 provide guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting in Topic 718, “Compensation—Stock Compensation.” ASU 2017-09 provides that an entity shall account for the effects of a modification of the terms or conditions of an equity award as an exchange of the original award for a new award, unless the fair value (or calculated value or intrinsic value, if such an alternative measurement method is used), the vesting conditions and the classification of the modified award are the same as the original award immediately before the award is modified. ASU 2017-09 requires reporting organizations to apply the amendments prospectively to an award modified on or after the adoption date. The adoption of ASU 2017-09 did not have a material effect on the Company’s consolidated financial statements.

In August 2018, the FASB issued Accounting Standards Update No. 2018-15, “Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40),” or ASU 2018-15, to help entities evaluate the accounting for costs of implementation activities incurred in a cloud computing arrangement that is a service contract. ASU 2018-15 aligns the requirements for deferring implementation costs incurred in a cloud computing arrangement that is a service contract with those incurred to develop or obtain internal-use software. ASU 2018-15 is effective for annual reporting periods, including interim periods within those periods, beginning after December 15, 2019, with early adoption permitted. The Company will be early-adopting ASU 2018-15 under the prospective transition method effective January 1, 2019.

In August 2018, the SEC issued release number 33-10532, “Disclosure Update and Simplification,” to facilitate the disclosure of information to investors and simplify compliance without significantly altering the total mix of information provided to investors. The amendments in this release are effective for annual reporting periods, including interim periods within those periods, beginning after November 5, 2018. As a result of the amendments, the Company will be required to, among other things, present, in the form of a reconciliation either as a separate statement or in the footnotes in interim and annual periods, an analysis of changes in each caption of stockholders’ equity and non-controlling interests, which will need to be accompanied by dividends per share and in the aggregate for its common shares outstanding.

Revenue Recognition

12 Months Ended

Dec. 31, 2018

Revenue From Contract With Customer [Abstract]

Revenue Recognition

3. REVENUE RECOGNITION

MSCI adopted the new revenue standard set forth under ASC Topic 606, as of January 1, 2018 using the Modified Retrospective Approach and as such, applied the new revenue standard only to contracts that were not completed at the January 1, 2018 adoption date, while prior reporting periods are not adjusted and continue to be reported in accordance to our historic accounting policy under Accounting Standards Codification 605 “Revenue Recognition.” The cumulative impact of adoption on the Company’s Consolidated Statement of Financial Condition was as follows (in thousands):

Selected line items	As reported at December 31, 2017		Adjustments due to Adoption of ASC Topic 606		Adjusted as of December 31, 2017
Statement of Financial Condition
Accounts receivable	$	327,597	$	145,803	$	473,400
Income taxes payable	$	14,828	$	4,314	$	19,142
Other accrued liabilities	$	85,710	$	5,128	$	90,838
Deferred revenue	$	374,365	$	120,226	$	494,591
Retained earnings	$	1,505,204	$	16,135	$	1,521,339

Included in the above adjustments is an increase of approximately $135.5 million primarily to accounts receivable and deferred revenue and other accrued liabilities with no impact to retained earnings. Under the new revenue standard, the Company now records an accounts receivable and an associated deferred revenue and other accrued liabilities when it bills the customer. Under the old revenue standard, these amounts were not recorded until the contract service start date.

The impact of adopting the new revenue standard on the Company’s Consolidated Statement of Income through the date of December 31, 2018 is as follows (in thousands):

	For the Year Ended December 31, 2018
Selected line items	As reported		Impact of Change			Without Adoption of ASC Topic 606
Statement of Income
Operating revenues	$	1,433,984	$	(6,181	)	$	1,427,803
Operating income	$	686,898	$	(6,181	)	$	680,717
Income before provision for income taxes	$	629,896	$	(6,181	)	$	623,715
Provision for income taxes	$	122,011	$	(1,236	)	$	120,775
Net income	$	507,885	$	(4,945	)	$	502,940
Earnings per basic common share	$	5.83	$	(0.06	)	$	5.77
Earnings per diluted common share	$	5.66	$	(0.06	)	$	5.60

The impact of adopting the new revenue standard on the Company’s Consolidated Statement of Financial Condition through the date of December 31, 2018 is as follows (in thousands):

	December 31, 2018
Selected line items	As reported		Impact of Change			Without Adoption of ASC Topic 606
Statement of Financial Condition
Accounts receivable	$	473,433	$	(148,209	)	$	325,224
Income taxes payable	$	16,253	$	(5,550	)	$	10,703
Other accrued liabilities	$	113,841	$	(6,078	)	$	107,763
Deferred revenue	$	537,977	$	(115,501	)	$	422,476
Retained earnings	$	1,856,951	$	(21,080	)	$	1,835,871

The table that follows presents the disaggregated revenues for the periods indicated (in thousands):

	For the Year Ended December 31, 2018
	Segments
	Index		Analytics		All Other		Total
Product Types
Recurring subscriptions	$	477,612	$	474,334	$	114,590	$	1,066,536
Asset-based fees		336,565		—		—		336,565
Non-recurring		21,298		5,605		3,980		30,883
Total	$	835,475	$	479,939	$	118,570	$	1,433,984

The table that follows presents the change in accounts receivable and deferred revenue between the dates indicated (in thousands):

	December 31, 2018
	Accounts receivable		Deferred revenue
Opening (1/1/2018)	$	473,400	$	494,591
Closing (12/31/2018)		473,433		537,977
Increase/(decrease)	$	33	$	43,386

The amount of revenue recognized in the period that was included in the opening current deferred revenue, which reflects the contract liability amounts, was $478.8 million. The difference between the opening and closing balances of the Company’s deferred revenue was primarily driven by an increase in billings, partially offset by the amortization of deferred revenue to operating revenues. MSCI had an insignificant long-term deferred revenue balance as of December 31, 2018 reflected as a part of “Other non-current liabilities” on its Consolidated Statement of Financial Condition.

The majority of MSCI’s contracts have a duration of one year or less and, accordingly, revenue associated with these performance obligations will be recognized within 12 months. For these contracts, the Company has chosen to use the practical expedient available under the new revenue standard and, as such, has not disclosed either the remaining performance obligation as of the end of the reporting period or when the Company expects to recognize the revenue. The remaining performance obligations for contracts that have a duration of greater than one year is $483.4 million as of December 31, 2018, which is expected to be recognized as follows:

•

Approximately $254.2 million of the remaining performance obligations over the next 12-month period;

•

Approximately $137.9 million of the remaining performance obligations over the second 12-month period;

•

Approximately $56.2 million of the remaining performance obligations over the third 12-month period; and

•

Approximately $35.1 million of the remaining performance obligations in the periods thereafter.

Earnings Per Common Share

12 Months Ended

Dec. 31, 2018

Earnings Per Share [Abstract]

Earnings Per Common Share

4. EARNINGS PER COMMON SHARE

Basic earnings per share (“EPS”) is computed by dividing income available to MSCI common shareholders by the weighted average number of common shares outstanding during the period. Common shares outstanding include common stock and vested restricted stock unit awards where recipients have satisfied either the explicit vesting terms or retirement-eligible requirements. Diluted EPS reflects the assumed conversion of all dilutive securities. There were 2,704, 987 and 398 anti-dilutive securities excluded from the calculation of diluted EPS for the years ended December 31, 2018, 2017 and 2016, respectively, because of their anti-dilutive effect.

The following table presents the computation of basic and diluted EPS:

	Years Ended
	December 31,		December 31,		December 31,
	2018		2017		2016
(in thousands, except per share data)
Net income	$	507,885	$	303,972	$	260,855

Basic weighted average common shares outstanding		87,179		90,336		95,986
Effect of dilutive securities:
Stock options and restricted stock units		2,522		1,578		554
Diluted weighted average common shares outstanding		89,701		91,914		96,540

Earnings per basic common share	$	5.83	$	3.36	$	2.72

Earnings per diluted common share	$	5.66	$	3.31	$	2.70

Commitments and Contingencies

12 Months Ended

Dec. 31, 2018

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

5. COMMITMENTS AND CONTINGENCIES

Legal matters. From time to time, the Company is party to various litigation matters incidental to the conduct of its business. The Company is not presently party to any legal proceedings the resolution of which the Company believes would have a material effect on its business, operating results, financial condition or cash flows.

Leases. The Company leases facilities under non-cancelable operating lease agreements. The terms of certain lease agreements provide for rental payments on a graduated basis. The Company recognizes rent expense on the straight-line basis over the lease period and has accrued for rent expense incurred but not paid. Rent expense for the years ended December 31, 2018, 2017 and 2016 was $25.3 million, $24.2 million and $24.2 million, respectively.

Future minimum commitments for the Company’s operating leases in place as of December 31, 2018 are as follows:

Years Ending December 31,	Amount
	(in thousands)
2019	$	25,868
2020		24,619
2021		23,452
2022		21,832
2023		21,818
Thereafter		107,800
Total	$	225,389

Senior Notes. The Company has issued an aggregate of $2.6 billion in senior unsecured notes (collectively, the “Senior Notes”) in the four discrete private offerings described below.

		Principal amount outstanding at		Carrying value at		Carrying value at		Fair Value at		Fair Value at
	Maturity Date	December 31, 2018		December 31, 2018		December 31, 2017		December 31, 2018		December 31, 2017
	(in thousands)
Long-term debt
5.25% senior unsecured notes due 2024	November 15, 2024	$	800,000	$	793,054	$	791,880	$	802,576	$	847,064
5.75% senior unsecured notes due 2025	August 15, 2025		800,000		793,016		791,967		807,088		858,848
4.75% senior unsecured notes due 2026	August 1, 2026		500,000		494,916		494,246		475,520		525,185
5.375% senior unsecured notes due 2027	May 15, 2027		500,000		494,516	—			489,745	—
Total debt		$	2,600,000	$	2,575,502	$	2,078,093	$	2,574,929	$	2,231,097

The fair market value of the Company’s debt obligations is determined in accordance with accounting standards related to the determination of fair value and represents Level 2 valuations, which are based on one or more quoted prices in markets that are not considered to be active or for which all significant inputs are observable, either directly or indirectly. The Company utilizes the market approach and obtains security pricing from a vendor who uses broker quotes and third-party pricing services to determine fair values.

The $800.0 million aggregate principal amount of 5.25% senior unsecured notes due 2024 (the “2024 Senior Notes”) are scheduled to mature and be paid in full on November 15, 2024. At any time prior to November 15, 2019, the Company may redeem all or part of the 2024 Senior Notes upon not less than 30 nor more than 60 days’ prior notice at a redemption price equal to the sum of (i) 100% of the principal amount thereof, plus (ii) a make-whole premium as of the date of redemption, plus (iii) accrued and unpaid interest and additional interest, if any, thereon, to the date of redemption. In addition, the Company may redeem all or part of the 2024 Senior Notes, together with accrued and unpaid interest, on or after November 15, 2019, at redemption prices set forth in the indenture governing the 2024 Senior Notes.

The $800.0 million aggregate principal amount of 5.75% senior unsecured notes due 2025 (the “2025 Senior Notes”) are scheduled to mature and be paid in full on August 15, 2025. At any time prior to August 15, 2020, the Company may redeem all or part of the 2025 Senior Notes upon not less than 30 nor more than 60 days’ prior notice at a redemption price equal to the sum of (i) 100% of the principal amount thereof, plus (ii) a make-whole premium as of the date of redemption, plus (iii) accrued and unpaid interest and additional interest, if any, thereon, to the date of redemption. In addition, the Company may redeem all or part of the 2025 Senior Notes, together with accrued and unpaid interest, on or after August 15, 2020, at redemption prices set forth in the indenture governing the 2025 Senior Notes.

The $500.0 million aggregate principal amount of 4.75% senior unsecured notes due 2026 (the “2026 Senior Notes”) are scheduled to mature and be paid in full on August 1, 2026. At any time prior to August 1, 2021, the Company may redeem all or part of the 2026 Senior Notes upon not less than 30 nor more than 60 days’ prior notice at a redemption price equal to the sum of (i) 100% of the principal amount thereof, plus (ii) a make-whole premium as of the date of redemption, plus (iii) accrued and unpaid interest and additional interest, if any, thereon, to the date of redemption. In addition, the Company may redeem all or part of the 2026 Senior Notes, together with accrued and unpaid interest, on or after August 1, 2021, at redemption prices set forth in the indenture governing the 2026 Senior Notes. At any time prior to August 1, 2019, the Company may use the proceeds of certain equity offerings to redeem up to 35% of the aggregate principal amount of the 2026 Senior Notes, including any permitted additional notes, at a redemption price equal to 104.75% of the principal amount plus accrued and unpaid interest, if any, to the redemption date.

On May 18, 2018, the Company completed its private offering of $500.0 million aggregate principal amount of 5.375% senior unsecured notes due 2027 (the “2027 Senior Notes”) reflected in the table above. The $495.0 million of net proceeds from the offering of the 2027 Senior Notes were allocated for general corporate purposes, including, without limitation, buybacks of the Company’s common stock and potential acquisitions.

The 2027 Senior Notes are scheduled to mature and be paid in full on May 15, 2027. At any time prior to May 15, 2022, the Company may redeem all or part of the 2027 Senior Notes upon not less than 30 nor more than 60 days’ prior notice at a redemption price equal to the sum of (i) 100% of the principal amount thereof, plus (ii) a make-whole premium as of the date of redemption, plus (iii) accrued and unpaid interest and additional interest, if any, thereon, to the date of redemption. In addition, the Company may redeem all or part of the 2027 Senior Notes, together with accrued and unpaid interest, on or after May 15, 2022, at redemption prices set forth in the indenture governing the 2027 Senior Notes. At any time prior to May 15, 2021, the Company may use the proceeds of certain equity offerings to redeem up to 35% of the aggregate principal amount of the 2027 Senior Notes, including any permitted additional notes, at a redemption price equal to 105.375% of the principal amount plus accrued and unpaid interest, if any, to the redemption date.

Interest payments attributable to the 2024 Senior Notes and 2027 Senior Notes are due on May 15th and November 15th of each year. Interest payments attributable to the 2025 Senior Notes are due on February 15th and August 15th of each year. Interest payments attributable to the 2026 Senior Notes are due on February 1st and August 1st of each year.

Revolver. On November 20, 2014, the Company entered into a $200.0 million senior unsecured revolving credit agreement (as amended, the “Revolving Credit Agreement”) with a syndicate of banks. The Revolving Credit Agreement had an initial term of five years with an option to extend for two additional one-year terms. On August 4, 2016, the Company entered into Amendment No. 1 (the “First Amendment”) to the Revolving Credit Agreement. The First Amendment, among other things, (i) increased aggregate commitments available to be borrowed to $220.0 million, (ii) increased the maximum consolidated leverage ratio and (iii) extended the initial term to August 2021 with an option to extend for an additional one-year term. On May 15, 2018, the Company entered into Amendment No. 2 (the “Second Amendment”) to the Revolving Credit Agreement. The Second Amendment, among other things, (i) increased aggregate commitments available to be borrowed to $250.0 million, (ii) extended the term to May 2023 with an option to extend for an additional one-year term and (iii) decreased the applicable rate and applicable fee rate for loans and commitments. At December 31, 2018, the Revolving Credit Agreement was undrawn.

In connection with the closings of the Senior Notes offerings and entry into the Revolving Credit Agreement and the First and Second Amendments, the Company paid certain fees which, together with the existing fees related to prior credit facilities, are being amortized over their related lives. At December 31, 2018, $26.3 million of the deferred financing fees remain unamortized, $0.4 million of which is included in “Prepaid and other assets,” $1.4 million of which is included in “Other non-current assets” and $24.5 million of which is grouped and presented as part of “Long-term debt” on the Consolidated Statement of Financial Condition.

Property, Equipment and Leasehold Improvements

12 Months Ended

Dec. 31, 2018

Property Plant And Equipment [Abstract]

Property, Equipment and Leasehold Improvements

6. PROPERTY, EQUIPMENT AND LEASEHOLD IMPROVEMENTS

Property, equipment and leasehold improvements at December 31, 2018 and 2017 consisted of the following:

		As of
	Estimated	December 31,			December 31,
	Useful Lives	2018			2017
		(in thousands)
Computer & related equipment	2 to 5 years	$	200,414		$	200,592
Furniture & fixtures	7 years		12,033			10,591
Leasehold improvements	1 to 21 years		53,429			51,128
Work-in-process	—		10,506			3,406
Subtotal			276,382			265,717
Accumulated depreciation and amortization			(185,505	)		(171,280	)
Property, equipment and leasehold improvements, net		$	90,877		$	94,437

Depreciation and amortization expense of property, equipment and leasehold improvements was $31.3 million, $35.4 million and $34.3 million for the years ended December 31, 2018, 2017 and 2016, respectively.

Goodwill and Intangible Assets

12 Months Ended

Dec. 31, 2018

Goodwill And Intangible Assets Disclosure [Abstract]

Goodwill and Intangible Assets

7. GOODWILL AND INTANGIBLE ASSETS

Goodwill

The change to the Company’s goodwill was as follows:

(in thousands)	Index			Analytics				All Other			Total
Goodwill at December 31, 2016	$	1,202,448		$	302,611			$	50,791		$	1,555,850
Foreign exchange translation adjustment		2,952			—				1,819			4,771
Goodwill at December 31, 2017	$	1,205,400		$	302,611			$	52,610		$	1,560,621
Changes to goodwill		—			(11,635	)	⁽¹⁾		—			(11,635	)
Foreign exchange translation adjustment		(1,996	)		—				(1,229	)		(3,225	)
Goodwill at December 31, 2018	$	1,203,404		$	290,976			$	51,381		$	1,545,761

⁽¹⁾	Reflects the $2.9 million and $8.7 million impact of the Financial Engineering Associates, Inc. (“FEA”) and Investor Force Holdings, Inc. (“InvestorForce”) divestitures, respectively. See Note 12, “Divestitures” for further information regarding the FEA and InvestorForce divestitures.

Through the year ended December 31, 2018, the Company has never recognized an impairment of goodwill on its consolidated financial statements.

Intangible Assets

Amortization expense related to intangible assets for the years ended December 31, 2018, 2017 and 2016 was $54.2 million, $44.5 million and $47.0 million, respectively. The amortization expense of acquired intangible assets for the years ended December 31, 2018, 2017 and 2016 was $44.0 million, $39.2 million and $44.6 million, respectively. The amortization expense of internally developed capitalized software for the years ended December 31, 2018, 2017 and 2016 was $10.2 million, $5.4 million and $2.4 million, respectively.

The gross carrying and accumulated amortization amounts related to the Company’s identifiable intangible assets were as follows:

		As of
	Estimated	December 31,			December 31,
	Useful Lives	2018			2017
		(in thousands)
Gross intangible assets:
Customer relationships⁽¹⁾	5 to 21 years	$	356,700		$	361,199
Trademarks/trade names⁽¹⁾	5 to 21.5 years		208,320			223,382
Technology/software^{(1), (2)}	3 to 8.5 years		238,692			225,407
Proprietary data	13 years		28,627			28,627
Subtotal			832,339			838,615
Foreign exchange translation adjustment			(9,569	)		(9,167	)
Total gross intangible assets		$	822,770		$	829,448
Accumulated amortization:
Customer relationships⁽¹⁾		$	(209,867	)	$	(189,100	)
Trademarks/trade names⁽¹⁾			(123,345	)		(116,691	)
Technology/software^{(1), (2)}			(198,974	)		(193,095	)
Proprietary data			(12,197	)		(10,352	)
Subtotal			(544,383	)		(509,238	)
Foreign exchange translation adjustment			2,416			1,626
Total accumulated amortization		$	(541,967	)	$	(507,612	)
Net intangible assets:
Customer relationships		$	146,833		$	172,099
Trademarks/trade names			84,975			106,691
Technology/software			39,718			32,312
Proprietary data			16,430			18,275
Subtotal			287,956			329,377
Foreign exchange translation adjustment			(7,153	)		(7,541	)
Total net intangible assets		$	280,803		$	321,836

⁽¹⁾ A portion of the change reflects the impact of the InvestorForce divestiture. See Note 12, “Divestitures” for further information regarding the InvestorForce divestiture.

⁽²⁾ A portion of the change reflects the impact of the FEA divestiture. See Note 12, “Divestitures” for further information regarding the FEA divestiture.

Estimated amortization expense for succeeding years is presented below:

Years Ending December 31,	Amortization Expense
	(in thousands)
2019	$	47,886
2020		46,339
2021		42,286
2022		35,819
2023		32,778
Thereafter		75,695
Total	$	280,803

Employee Benefits

12 Months Ended

Dec. 31, 2018

Compensation And Retirement Disclosure [Abstract]

Employee Benefits

8. EMPLOYEE BENEFITS

The Company sponsors a 401(k) plan for eligible U.S. employees and defined contribution and defined benefit pension plans that cover substantially all of its non-U.S. employees. For the years ended December 31, 2018, 2017 and 2016, costs relating to 401(k), pension and post-retirement benefit expenses were $22.8 million, $22.5 million and $21.6 million, respectively, which are included in various categories on the Company’s Consolidated Statements of Income. Amounts included in “Cost of revenues” for the years ended December 31, 2018, 2017 and 2016 were $10.2 million, $10.3 million and $9.5 million, respectively. Amounts included in “Selling and marketing” for the years ended December 31, 2018, 2017 and 2016 were $6.9 million, $6.5 million and $6.7 million, respectively. Amounts included in “Research and development” for the years ended December 31, 2018, 2017 and 2016 were $3.8 million, $3.8 million and $4.0 million, respectively. Amounts included in “General and administrative” for the years ended December 31, 2018, 2017 and 2016 were $1.8 million, $1.3 million and $1.3 million, respectively. Amounts included in “Other expense (income)” for the years ended December 31, 2018 and 2017 were less than $0.1 million and $0.6 million, respectively.

401(k) and Other Defined Contribution Plans. Eligible employees may participate in the MSCI 401(k) plan (or any other regional defined contribution plan sponsored by MSCI) immediately upon hire. Eligible employees receive 401(k) and other defined contribution plan matching contributions, which are subject to vesting and certain other limitations. The Company’s expenses associated with the 401(k) plan and other defined contribution plans for the years ended December 31, 2018, 2017 and 2016 were $19.2 million, $18.6 million and $17.6 million, respectively.

Net Periodic Benefit Expense. Net periodic benefit expense incurred by the Company related to defined benefit pension plans was $3.6 million, $3.9 million and $4.0 million for the years ended December 31, 2018, 2017 and 2016, respectively.

The Company uses a measurement date of December 31 to calculate obligations under its pension and postretirement plans. As of December 31, 2018 and 2017, the Company carried a net liability of $21.3 million and $22.0 million, respectively, in “Other non-current liabilities” on the Consolidated Statement of Financial Condition related to its future pension obligations. The fair value of the defined benefit plan assets were $21.7 million and $20.6 million at December 31, 2018 and 2017, respectively.

Shareholders' Equity (Deficit)

12 Months Ended

Dec. 31, 2018

Equity [Abstract]

Shareholders' Equity (Deficit)

9. SHAREHOLDERS’ EQUITY (DEFICIT)

This note reflects the share repurchases and related activity as well as share-based compensation activity recognized by the Company, for all periods referenced.

Return of capital

On October 26, 2016, the Board of Directors approved a stock repurchase program for the purchase of up to $750.0 million worth of shares of the Company’s common stock (together with the amount then remaining under a previously existing share repurchase program, the “2016 Repurchase Program”).

On May 1, 2018, the Board of Directors authorized an additional stock repurchase program for the purchase of up to $1.0 billion worth of shares of the Company’s common stock (together with the $523.1 million of authorization then remaining under the 2016 Repurchase Program, the “2018 Repurchase Program”). Share repurchases made pursuant to the 2018 Repurchase Program may take place in the open market or in privately negotiated transactions from time to time based on market and other conditions. This authorization may be modified, suspended or terminated by the Board of Directors at any time without prior notice. As of December 31, 2018, there was $808.1 million of available authorization remaining under the 2018 Repurchase Program.

The following table provides information with respect to repurchases of the Company’s common stock pursuant to open market repurchases:

Year Ended	Average Price Paid Per Share		Total Number of Shares Repurchased		Dollar Value of Shares Repurchased
	(in thousands, except per share data)
December 31, 2018	$	148.34		6,236	$	924,989
December 31, 2017	$	87.96		1,556	$	136,899
December 31, 2016	$	73.71		10,303	$	759,427

The following table presents cash dividends declared and distributed per common share for the periods indicated:

	Dividends
	Per Share		Declared		Distributed		Deferred
2018	(in thousands, except per share data)
Three Months Ended March 31,	$	0.38	$	34,848	$	34,900	$	(52	)
Three Months Ended June 30,		0.38		34,254		33,935		319
Three Months Ended September 30,		0.58		52,264		51,764		500
Three Months Ended December 31,		0.58		50,907		50,434		473
Year Ended December 31,	$	1.92	$	172,273	$	171,033	$	1,240
2017
Three Months Ended March 31,	$	0.28	$	25,769	$	25,500	$	269
Three Months Ended June 30,		0.28		25,710		25,444		266
Three Months Ended September 30,		0.38		34,768		34,403		365
Three Months Ended December 31,		0.38		34,745		34,448		297
Year Ended December 31,	$	1.32	$	120,992	$	119,795	$	1,197
2016
Three Months Ended March 31,	$	0.22	$	22,046	$	21,889	$	157
Three Months Ended June 30,	0.22			21,588		21,391		197
Three Months Ended September 30,	0.28			26,936		26,680		256
Three Months Ended December 31,	0.28			26,524		26,304		220
Year Ended December 31,	$	1.00	$	97,094	$	96,264	$	830

Common Stock

The following table presents activity related to shares of common stock issued and repurchased for the periods indicated:

	Common		Treasury			Common Stock
	Stock Issued		Stock			Outstanding
Balance At December 31, 2015		128,200,189		(27,187,041	)		101,013,148
Dividend payable/paid		892		(472	)		420
Common stock issued and exercise of stock options		788,304		—			788,304
Shares withheld for tax withholding and exercises		—		(219,921	)		(219,921	)
Shares repurchased under stock repurchase programs		—		(10,303,047	)		(10,303,047	)
Shares issued to directors		6,959		(6,273	)		686
Balance At December 31, 2016		128,996,344		(37,716,754	)		91,279,590
Dividend payable/paid		684		(528	)		156
Common stock issued and exercise of stock options		538,448		—			538,448
Shares withheld for tax withholding and exercises		—		(157,667	)		(157,667	)
Shares repurchased under stock repurchase programs		—		(1,556,313	)		(1,556,313	)
Shares issued to directors		8,380		(7,709	)		671
Balance At December 31, 2017		129,543,856		(39,438,971	)		90,104,885
Dividend payable/paid		734		(579	)		155
Common stock issued and exercise of stock options		479,277		—			479,277
Shares withheld for tax withholding and exercises		—		(174,991	)		(174,991	)
Shares repurchased under stock repurchase programs		—		(6,235,629	)		(6,235,629	)
Shares issued to directors		6,059		(5,618	)		441
Balance At December 31, 2018		130,029,926		(45,855,788	)		84,174,138

Shared-Based Compensation

The Company regularly issues share-based compensation to its employees and directors who are not employees of the Company. The accounting guidance for share-based compensation requires measurement of compensation cost for share-based awards at fair value and recognition of compensation cost over the service period, net of estimated forfeitures.

In February 2019, the Company granted a portion of its employees awards in the form of RSUs and MSUs. The total number of units granted was 396,090. The aggregate fair value of the awards was $50.4 million, of which approximately $0.2 million had been expensed in the year ended December 31, 2018 in relation to awards granted to retirement-eligible employees under the award terms. A portion of the awards granted consisted of RSUs vesting over a three-year period, with one-third vesting on each anniversary of the grant in 2020, 2021 and 2022. A smaller portion of the awards granted consisted of MSUs that will time-vest over a three-year period and a five-year period and are subject to the achievement of the applicable absolute total shareholder return compounded annual growth rate measured over a three-year and five-year performance period, respectively.

For a small group of awards granted by the Company, all or a portion of the award may be cancelled in certain limited situations, including termination for cause, if employment is terminated before the end of the relevant restriction period. For the remainder of the awards granted by the Company, all or a portion of the award may be canceled if employment is terminated for certain reasons before the end of the relevant restriction period for non-retirement-eligible employees.

In connection with awards under its equity-based compensation and benefit plans, the Company is authorized to use newly issued shares or certain shares of common stock held in treasury.

The components of share-based compensation expense related to the awards to Company employees and directors who are not employees of the Company are presented below:

	Years Ended
	December 31,		December 31,		December 31,
(in thousands)	2018		2017		2016
Share-based Awards	$	40,563	$	37,921	$	32,525

The following table presents the amount of share-based compensation expense by category for the periods indicated:

	Years Ended
	December 31,		December 31,		December 31,
(in thousands)	2018		2017		2016
Cost of revenues	$	10,334	$	9,707	$	7,971
Selling and marketing		12,851		11,355		9,526
Research and development		4,175		3,477		2,970
General and administrative		13,203		13,382		12,058
Total share-based compensation expense	$	40,563	$	37,921	$	32,525

The tax benefits for share-based compensation expense related to RSUs, PSUs and MSUs (together, the “Share-based Awards”) as well as stock options granted to Company employees and to directors who are not employees of the Company were $8.8 million, $5.5 million and $7.4 million for the years ended December 31, 2018, 2017 and 2016, respectively.

As of December 31, 2018, $24.6 million of compensation cost related to MSCI unvested share-based awards granted to the Company’s employees and to directors who are not employees of the Company had not yet been recognized. The unrecognized compensation cost relating to unvested stock-based awards expected to vest will be recognized primarily over the next one to three years.

In connection with awards under its equity-based compensation and benefit plans, the Company is authorized to issue shares of common stock. As of December 31, 2018, 7.0 million shares of common stock were available for future grants under these plans.

Share-based Awards. Certain Company employees have been granted share-based awards pursuant to a share-based compensation plan. The plan provides for the deferral of a portion of certain employees’ discretionary compensation with awards made in the form of Share-based Awards. Recipients of Share-based Awards generally have rights to receive dividend equivalents that are subject to vesting. The Company reports the target number of PSUs and MSUs granted unless it has determined, based on the actual achievement of performance measures, that an employee will receive a different amount of shares underlying the PSUs and MSUs, in which case the Company reports the amount of shares employees are likely to receive.

The following table presents activity concerning the Company’s vested and unvested Share-based Awards applicable to its employees (share data in thousands) for the period indicated:

				Weighted
				Average
				Grant
	Number of			Date Fair
For the Year Ended December 31, 2018	Shares			Value
Vested and unvested Share-based Awards at December 31, 2017		1,419		$	68.50
Granted		332		$	117.64
Conversion to common stock		(451	)	$	65.40
Canceled		(12	)	$	87.17
Vested and unvested Share-based Awards at December 31, 2018 ⁽¹⁾		1,288		$	82.09

⁽¹⁾	As of December 31, 2018, 1,261 Share-based Awards, with a weighted average price of $81.51, were vested or expected to vest.

The total fair value of Share-based Awards held by the Company’s employees that converted to MSCI common stock during the years ended December 31, 2018, 2017 and 2016 was $63.6 million, $30.3 million and $39.4 million, respectively.

The following table presents activity concerning the Company’s unvested Share-based Awards related to its employees (share data in thousands):

				Weighted
				Average
				Grant
	Number of			Date Fair
For the Year Ended December 31, 2018	Shares			Value
Unvested Share-based Awards at December 31, 2017		1,166		$	69.96
Granted		280		$	124.66
Vested		(332	)	$	68.41
Canceled		(12	)	$	87.17
Unvested Share-based Awards at December 31, 2018		1,102		$	84.14

Unvested Share-based Awards expected to vest		1,075		$	83.51

Stock Option Awards. No stock options were issued during the years ended December 31, 2018, 2017 and 2016.

The following table presents activity concerning MSCI stock options granted to the Company’s employees for the year ended December 31, 2018 (option data and dollar values in thousands, except exercise price):

						Weighted
				Weighted		Average
	Number			Average		Remaining		Aggregated
	of			Exercise		Life		Intrinsic
For the Year Ended December 31, 2018	Options			Price		(Years)		Value
Options outstanding at December 31, 2017		145		$	26.47		2.11	$	14,519
Granted or assumed		—		$	—	N/A		N/A
Forfeited		—		$	—	N/A		N/A
Conversion to common stock		(33	)	$	18.14	N/A		N/A
Options outstanding and exercisable at December 31, 2018		112		$	28.96	1.28		$	13,239

All outstanding stock options as of December 31, 2018 are vested and exercisable.

The following table presents information relating to the Company’s outstanding and exercisable stock options as of December 31, 2018 (number of options outstanding and aggregate intrinsic value data in thousands):

As of December 31, 2018		Options Outstanding
				Weighted		Average
				Average		Remaining		Aggregate
		Number		Exercise		Life		Intrinsic
Range of Exercise Prices		Outstanding		Price		(Years)		Value
$15.18 to $16.48			12	$	16.48		0.15	$	1,521
$20.45 to $24.11			14	$	20.45		0.65	$	1,798
$	25.64		36	$	25.64		0.96	$	4,409
$	36.70		50	$	36.70		1.95	$	5,511
Total			112					$	13,239

The intrinsic value of the stock options exercised by the Company’s employees during the years ended December 31, 2018, 2017 and 2016 was $4.8 million, $10.9 million and $11.3 million, respectively.

Reclassifications out of Accumulated Other Comprehensive Income (Loss)

12 Months Ended

Dec. 31, 2018

Statement Of Income And Comprehensive Income [Abstract]

Reclassifications out of Accumulated Other Comprehensive Income (Loss)

10. RECLASSIFICATIONS OUT OF ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)

As required by ASC Subtopic 220-10, “Comprehensive Income—Overall,” the following table presents the amounts reclassified from accumulated other comprehensive income (loss) by the respective line item in the Consolidated Statement of Income:

Reclassifications Out of Accumulated Other Comprehensive Income (Loss) ⁽¹⁾


Details about Accumulated Other	Amount Reclassified from Accumulated									Affected Line Item in the
Comprehensive Income (Loss) Components	Other Comprehensive Income (Loss)									Consolidated Statements of Income
	Years Ended
	December 31,			December 31,			December 31,
	2018			2017			2016
				(in thousands)
Defined benefit pension plans
Amount recognized as a component of net periodic benefit expense for curtailments and settlements	$	(222	)	$	(281	)	$	(261	)
Income Taxes	54			77			73			Provision for income taxes
Total reclassifications for the period, net of tax	$	(168	)	$	(204	)	$	(188	)

⁽¹⁾	Amounts in parentheses indicate expenses or losses moved to the Consolidated Statements of Income.

Income Taxes

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Income Taxes

11. INCOME TAXES

The provision for income taxes (benefits) by taxing jurisdiction consisted of:

	Years Ended
	December 31,			December 31,			December 31,
	2018			2017			2016
	(in thousands)
Current
U.S. federal	$	51,316		$	133,250		$	93,071
U.S. state and local		31,680			16,312			16,363
Non U.S.		39,795			32,267			32,616
		122,791			181,829			142,050
Deferred
U.S. federal		(1,406	)		(12,502	)		(13,010	)
U.S. state and local		5,566			(2,119	)		(2,235	)
Non U.S.		(4,940	)		(4,281	)		(1,722	)
		(780	)		(18,902	)		(16,967	)

Provision for income taxes	$	122,011		$	162,927		$	125,083

The following table reconciles the U.S. federal statutory income tax rate to the effective income tax rate:

	Years Ended
	December 31,			December 31,			December 31,
	2018			2017			2016
U.S. federal statutory income tax rate		21.00	%		35.00	%		35.00	%
U.S. state and local income taxes, net of U.S. federal income tax benefits		4.66	%		1.84	%		2.38	%
Change in tax rates applicable to non-U.S. earnings		(2.20	%)		(7.60	%)		(3.73	%)
Domestic tax credits and incentives		(0.30	%)		(0.24	%)		(0.26	%)
Net tax charge related to Tax Reform		(1.78	%)		7.40	%		—	%
Valuation allowance		(1.41	%)		—	%		—	%
Excess Stock Based Compensation		(1.14	%)		(1.25	%)		—	%
Other		0.54	%		(0.25	%)		(0.98	%)
Effective income tax rate		19.37	%		34.90	%		32.41	%

On December 22, 2017, the U.S. government enacted comprehensive tax legislation commonly referred to as the Tax Cuts and Jobs Act (“Tax Reform”). Given the significance of the legislation, the SEC staff issued Staff Accounting Bulletin No. 118, “Income Tax Accounting Implications of the Tax Cuts and Jobs Act,” (“SAB 118”), which allowed registrants to record provisional amounts during a one year “measurement period” similar to that used when accounting for business combinations.

Tax Reform significantly revised the U.S. corporate income tax by, among other things, lowering U.S. corporate income tax rates, implementing a territorial tax system and imposing a one-time tax on deemed repatriation of historic earnings and profits (“E&P”) of foreign subsidiaries (the “Toll Charge”). The provisions of Tax Reform began impacting the Company for the annual reporting periods, including interim periods within those periods, beginning after December 31, 2017 as well as during the three months ended December 31, 2017. The U.S. federal income tax rate reduction was effective as of January 1, 2018.

In the year ended December 31, 2017, the Company’s provisional accounting for the effects of Tax Reform resulted in a net charge of $34.5 million in the provision for income taxes for MSCI that primarily included an estimated tax charge of approximately $47.5 million related to the Toll Charge and an estimated tax charge of approximately $16.0 million related to a change in assertion that those profits were permanently reinvested overseas as of December 31, 2017, partially offset by an estimated tax benefit of approximately $29.0 million related to the revaluation of deferred taxes at the now-lower statutory corporate rate.

In the year ended December 31, 2018, the Company finalized the Toll Charge and determined the final impact of Tax Reform, resulting in a net benefit of $11.2 million that included a benefit of $5.7 million on the change to the provisional estimate of the Toll Charge and a benefit of $2.6 million for a reduction in the expected withholding taxes from Switzerland. The Company also recorded a benefit of $2.9 million related to the revaluation of deferred taxes at the lower statutory rate as a result of tax planning. The cumulative net charge of Tax Reform was $23.3 million.

Deferred income taxes reflect the net tax effects of temporary differences between the financial reporting and tax bases of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when such differences are expected to reverse. Significant components of the Company’s deferred tax assets and liabilities as of December 31, 2018 and 2017, were as follows:

	As of
	December 31,			December 31,
	2018			2017
	(in thousands)
Deferred tax assets:
Employee compensation and benefit plans	$	19,698		$	19,646
Deferred rent		5,392			5,308
Pension		2,466			1,520
Unearned revenue		—			853
Loss carryforwards - non-current		2,941			18,105
Other		—			1,435
Subtotal		30,497			46,867
Less: valuation allowance		(632	)		(11,575	)
Total deferred tax assets	$	29,865		$	35,292
Deferred tax liabilities:
Intangible assets	$	(65,538	)	$	(73,634	)
Unearned revenue		(1,170	)		—
Unremitted foreign earnings		(12,872	)		(16,108	)
Property, equipment and leasehold improvements, net		(16,369	)		(11,564	)
Other		(1,021	)		—
Total deferred tax liabilities	$	(96,970	)	$	(101,306	)
Net deferred tax liabilities	$	(67,105	)	$	(66,014	)

During the year ended December 31, 2018, the Company sold two of its U.S. subsidiaries, InvestorForce and FEA. See Note 12, “Divestitures,” for additional information. As a result of these divestitures, the Company was able to utilize the $42.4 million of capital loss carryover held on the books, against which a full valuation allowance was recorded. The tax value of the U.S. portion of the net operating loss carryforwards is $16.0 million which is subject to an annual limitation on utilization and will begin to expire in 2024. As of December 31, 2018, the tax value of foreign net operating loss carryforwards was $0.6 million with a related valuation allowance of $0.6 million.

The following table presents changes in the Company’s deferred tax asset valuation allowance for the periods indicated:

	Years Ended
	December 31,			December 31,			December 31,
	2018			2017			2016
	(in thousands)
Beginning balance	$	11,575		$	17,807		$	21,052
Additions charged to cost and expenses		—			324			1,862
Additions charged to other accounts		—			—			—
Deductions		(10,943	)		(6,556	)		(5,107	)
Ending balance	$	632		$	11,575		$	17,807

The following table presents the components of income before provision for income taxes generated by domestic or foreign operations for the periods indicated:

	Years Ended
	December 31,		December 31,		December 31,
	2018		2017		2016
	(in thousands)
Domestic	$	399,000	$	283,779	$	263,536
Foreign ⁽¹⁾		230,896		183,120		122,402
Total income before provision for income taxes	$	629,896	$	466,899	$	385,938

⁽¹⁾	Foreign income before provision for income taxes is defined as income generated from operations located outside the U.S., which includes income from foreign branches of U.S. companies.

Cumulative earnings attributable to foreign subsidiaries were $289.5 million, $450.7 million and $341.6 million for the years ended December 31, 2018, 2017, and 2016, respectively. The Company has recorded a $16.0 million charge to provision for income taxes related to foreign withholding taxes that would be payable upon repatriation. As of December 31, 2018, the Company asserts that the earnings in its India subsidiary accumulated after January 1, 2018 will be permanently reinvested.

The Company regularly assesses the likelihood of additional assessments in each of the taxing jurisdictions in which it files income tax returns. The Company has established unrecognized tax benefits that the Company believes are adequate in relation to the potential for additional assessments. Once established, the Company adjusts unrecognized tax benefits only when more information is available or when an event occurs necessitating a change. As part of the Company’s periodic review of unrecognized tax benefits and based on new information regarding the status of federal and state examinations, the Company’s unrecognized tax benefits are remeasured. It is reasonably possible that significant changes in the balance of unrecognized tax benefits may occur within the next 12 months. At this time, however, it is not possible to reasonably estimate the expected change to the total amount of unrecognized tax benefits and the impact on the effective tax rate over the next 12 months.

The Company believes the resolution of tax matters will not have a material effect on the Consolidated Statement of Financial Condition of the Company, although a resolution could have a material impact on the Company’s Consolidated Statement of Income for a particular future period and on the Company’s effective tax rate for any period in which such resolution occurs.

The following table presents a reconciliation of the beginning and ending amount of the gross unrecognized tax benefits, excluding interest and penalties, for the years ended December 31, 2018, 2017 and 2016:

	Years Ended
	December 31,			December 31,			December 31,
Gross unrecognized tax benefits	2018			2017			2016
(in thousands)
Beginning balance	$	10,022		$	7,936		$	8,692
Increases based on tax positions related to the current period		3,928			3,389			575
Increases based on tax positions related to prior periods		1,892			519			135
Decreases based on tax positions related to prior periods		(297	)		(6	)		(3	)
Decreases related to settlements with taxing authorities		—			(1,152	)		(1,463	)
Decreases related to a lapse of applicable statute of limitations		(1,454	)		(664	)		—
Ending balance	$	14,091		$	10,022		$	7,936

The total amount of unrecognized tax benefits was $13.8 million, net of federal benefit of state issues, competent authority and foreign tax credit offsets, as of December 31, 2018, which, if recognized, would favorably affect the effective tax rate in future periods. The Company recognizes the accrual of interest and penalties related to unrecognized tax benefits in the “Provision for income taxes” in the Consolidated Statement of Income. For the year ended December 31, 2018, the Company recognized $0.2 million of interest in the Consolidated Statement of Income with respect to unrecognized tax benefits. No significant penalties were recognized in the Consolidated Statement of Income for the year ended December 31, 2018. The amount of accrued interest, which includes interest related to uncertain tax positions and accrued income tax expense, recorded on the Consolidated Statement of Financial Condition as of December 31, 2018 was $0.9 million.

The Company is under examination by the IRS and other tax authorities in certain jurisdictions, including foreign jurisdictions, such as India, and states in which the Company has significant operations, such as New York. The tax years currently under examination vary by jurisdiction but include years ranging from 2006 through 2017. As a result of having previously been a member of the Morgan Stanley consolidated group, the Company may have future settlements with Morgan Stanley related to the ultimate disposition of their New York State and New York City examination relating to the tax years 2007 and 2008 and their IRS examination relating to the tax years 2006 through 2008. The Company does not believe it has any material exposure to the New York State and New York City examinations. Additionally, the Company believes it has adequate reserves for any tax issues that may arise out of the IRS examination relating to the tax years 2006 through 2008 and therefore does not believe any related settlement with Morgan Stanley will have a material impact.

Divestitures

12 Months Ended

Dec. 31, 2018

Discontinued Operations And Disposal Groups [Abstract]

Divestitures

12. DIVESTITURES

Divestiture of FEA

On April 9, 2018, MSCI completed the FEA divestiture for $21.0 million in cash. The sale included $2.9 million of goodwill, $2.7 million of fully amortized identifiable intangible assets, $6.1 million of other net assets and $1.4 million of transaction costs, which resulted in a gain of $10.6 million included in “Other expense (income)” within the Consolidated Statement of Income. FEA was included as a component of the Analytics segment through the date of divestiture. The results of operations from FEA were not material to the Company.

Divestiture of InvestorForce

On October 12, 2018, the Company completed the InvestorForce divestiture for $62.0 million in cash plus an additional $0.8 million for working capital adjustment which is subject to change, $8.7 million of allocated goodwill, $4.0 million of identifiable intangible assets, net of accumulated amortization, $0.7 million of other net assets and $2.8 million of transaction costs, which resulted in a gain of approximately $46.6 million included in “Other expense (income)” within the Consolidated Statement of Income. InvestorForce was included as a component of the Analytics segment through the date of divestiture. The results of operations from InvestorForce were not material to the Company.

Segment Information

12 Months Ended

Dec. 31, 2018

Segment Reporting [Abstract]

Segment Information

13. SEGMENT INFORMATION

ASC Subtopic 280-10, “Segment Reporting,” establishes standards for reporting information about operating segments. Operating segments are defined as components of an enterprise about which separate financial information is available that is evaluated regularly by the chief operating decision maker, or CODM, in deciding how to allocate resources and assess performance. MSCI’s Chief Executive Officer and its President, who are considered to be its CODM, review financial information presented on an operating segment basis for purposes of making operating decisions and assessing financial performance.

The CODM measures and evaluates reportable segments based on segment operating revenues as well as Adjusted EBITDA and other measures. The Company excludes the following items from segment Adjusted EBITDA: provision for income taxes, other expense (income), net, depreciation and amortization of property, equipment and leasehold improvements, amortization of intangible assets and, at times, certain other transactions or adjustments that the CODM does not consider for the purposes of making decisions to allocate resources among segments or to assess segment performance. Although these amounts are excluded from segment Adjusted EBITDA, they are included in reported consolidated net income and are included in the reconciliation that follows.

The Company’s computation of segment Adjusted EBITDA may not be comparable to other similarly titled measures computed by other companies because all companies do not calculate segment Adjusted EBITDA in the same fashion.

Operating revenues and expenses directly associated with each segment are included in determining its operating results. Other expenses that are not directly attributable to a particular segment are based upon allocation methodologies, including time estimates, revenue, headcount, sales targets, data center consumption and other relevant usage measures. Due to the integrated structure of our business, certain costs incurred by one segment may benefit other segments. A segment may use the content and data produced by another segment without incurring an arm’s-length intersegment charge.

The CODM does not review any information regarding total assets on an operating segment basis. Operating segments do not record intersegment revenue, and, accordingly, there is none to be reported. The accounting policies for segment reporting are the same as for MSCI as a whole.

The Company has four operating segments: Index, Analytics, ESG and Real Estate.

The Index operating segment is primarily a provider of equity indexes. The indexes are used in many areas of the investment process, including index-linked product creation and performance benchmarking, as well as portfolio construction and rebalancing and asset allocation.

The Analytics operating segment offers risk management, performance attribution and portfolio management content, applications and services that provide clients with an integrated view of risk and return and an analysis of market, credit, liquidity and counterparty risk across all major asset classes, spanning short, medium and long-term time horizons. Clients access Analytics content through MSCI’s own proprietary applications and application programming interfaces, or through third party applications or directly on their own platforms. The Analytics operating segment also provides various managed services to help clients operate more efficiently as well as address the needs of certain specialized areas of the investment community by providing a reporting service and performance reporting tools to institutional consultants and investors in hedge funds.

The ESG operating segment offers products and services that help institutional investors understand how ESG factors can impact the long-term risk of their investments. In addition, MSCI ESG Research data and ratings are used in the construction of equity and fixed income indexes to help institutional investors more effectively benchmark ESG investment performance, issue index-based investment products, as well as manage, measure and report on ESG mandates.

The Real Estate operating segment includes research, reporting, market data and benchmarking offerings that provide real estate performance analysis for funds, investors and managers. Real Estate performance and risk analytics range from enterprise-wide to property-specific analysis. The Real Estate operating segment also provides business intelligence to real estate owners, managers, developers and brokers worldwide. During the year ended December 31, 2016, the Company disposed of the Real Estate occupiers business and recorded an immaterial gain on the disposition which was recorded in “Other expense (income),” in the Consolidated Statement of Income.

The operating segments of ESG and Real Estate do not individually meet the segment reporting thresholds and have been combined and presented as part of All Other for disclosure purposes.

The following table presents operating revenues by reportable segment for the periods indicated:

		Years Ended
		December 31,		December 31,		December 31,
		2018		2017		2016
	(in thousands)
Operating revenues
Index		$	835,475	$	718,959	$	613,551
Analytics			479,939		458,269		448,353
All Other			118,570		96,944		88,765
Total		$	1,433,984	$	1,274,172	$	1,150,669

The following table presents segment profitability and a reconciliation to net income for the periods indicated:

		Years Ended
		December 31,		December 31,		December 31,
		2018		2017		2016
	(in thousands)
Index Adjusted EBITDA		$	607,853	$	522,241	$	431,478
Analytics Adjusted EBITDA			143,645		125,624		128,507
All Other Adjusted EBITDA			20,935		11,892		9,472
Total operating segment profitability			772,433		659,757		569,457
Amortization of intangible assets			54,189		44,547		47,033
Depreciation and amortization of property, equipment and leasehold improvements			31,346		35,440		34,320
Operating income			686,898		579,770		488,104
Other expense (income), net			57,002		112,871		102,166
Provision for income taxes			122,011		162,927		125,083
Net income		$	507,885	$	303,972	$	260,855

Revenue by geography is based on the shipping address of the ultimate customer utilizing the product. The following table presents revenue by geographic area for the periods indicated:

	Years Ended
	December 31,		December 31,		December 31,
(in thousands)	2018			2017	2016
Operating revenues
Americas:
United States	$	662,345	$	622,132	$	556,777
Other		58,065		48,139		45,185
Total Americas		720,410		670,271		601,962
Europe, the Middle East and Africa ("EMEA"):
United Kingdom		214,204		193,831		175,749
Other		293,252		250,267		229,010
Total EMEA		507,456		444,098		404,759
Asia & Australia:
Japan		67,100		54,351		52,161
Other		139,018		105,452		91,787
Total Asia & Australia		206,118		159,803		143,948
Total	$	1,433,984	$	1,274,172	$	1,150,669

Long-lived assets consist of property, equipment, leasehold improvements, goodwill and intangible assets, net of accumulated depreciation and amortization. The following table presents long-lived assets by geographic area on the dates indicated:

	As of
	December 31,		December 31,
	2018		2017
	(in thousands)
Long-lived assets
Americas:
United States	$	1,803,321	$	1,847,605
Other		6,560		1,685
Total Americas		1,809,881		1,849,290
EMEA:
United Kingdom		80,039		94,782
Other		19,369		22,394
Total EMEA		99,408		117,176
Asia & Australia:
Japan		411		432
Other		7,741		9,996
Total Asia & Australia		8,152		10,428
Total	$	1,917,441	$	1,976,894

Quarterly Results of Operations

12 Months Ended

Dec. 31, 2018

Quarterly Financial Information Disclosure [Abstract]

Quarterly Results of Operations

14. QUARTERLY RESULTS OF OPERATIONS (unaudited):

	2018												2017
	First			Second			Third			Fourth			First			Second			Third			Fourth
	Quarter			Quarter			Quarter			Quarter			Quarter			Quarter			Quarter			Quarter
	(in thousands, except per share data)
Operating revenues	$	351,316		$	363,046		$	357,934		$	361,688		$	301,207		$	316,089		$	322,097		$	334,779
Cost of revenues		71,304			71,368			70,906			73,757			67,463			68,538			68,433			69,247
Selling and marketing		46,409			47,416			46,149			52,949			42,972			41,550			44,873			47,726
Research and development		20,707			19,801			20,591			20,312			18,970			18,196			17,974			20,709
General and administrative		26,187			24,036			24,751			24,908			20,981			21,424			22,079			23,280
Amortization of intangible assets		11,338			19,537			11,681			11,633			11,251			11,122			10,614			11,560
Depreciation and amortization of property, equipment and leasehold improvements		8,205			7,377			7,453			8,311			8,838			9,159			9,325			8,118
Total operating expenses		184,150			189,535			181,531			191,870			170,475			169,989			173,298			180,640
Operating income		167,166			173,511			176,403			169,818			130,732			146,100			148,799			154,139
Interest income		(2,770	)		(4,281	)		(6,522	)		(6,096	)		(932	)		(1,310	)		(1,835	)		(2,237	)
Interest expense		29,560			31,761			35,902			35,891			29,024			29,027			29,020			29,027
Other expense (income)		938			(10,292	)		177			(47,266	)		1,015			872			811			389
Other expense (income), net		27,728			17,188			29,557			(17,471	)		29,107			28,589			27,996			27,179
Income before provision for income taxes		139,438			156,323			146,846			187,289			101,625			117,511			120,803			126,960
Provision for income taxes		24,346			39,494			23,014			35,157			28,674			36,245			35,650			62,358
Net income	$	115,092		$	116,829		$	123,832		$	152,132		$	72,951		$	81,266		$	85,153		$	64,602

Earnings per basic common share	$	1.28		$	1.31		$	1.39		$	1.75		$	0.80		$	0.90		$	0.94		$	0.72

Earnings per diluted common share	$	1.24		$	1.28		$	1.36		$	1.70		$	0.80		$	0.89		$	0.93		$	0.70

Weighted average shares outstanding used in computing per share data
Basic		90,075			89,112			88,796			86,968			90,708			90,404			90,112			90,130
Diluted		92,587			91,586			91,372			89,495			91,624			91,708			91,868			92,467

Subsequent Events

12 Months Ended

Dec. 31, 2018

Subsequent Events [Abstract]

Subsequent Events

15. SUBSEQUENT EVENTS

On January 30, 2019, the Board of Directors of the Company declared a quarterly dividend of $0.58 per share of common stock to be paid on March 15, 2019 to shareholders of record as of the close of trading on February 22, 2019.

Subsequent to the year ended December 31, 2018 and through February 15, 2019, the Company repurchased an additional 0.7 million shares of common stock at an average price of $147.97 per share for a total value of $102.1 million.

Introduction and Basis of Presentation (Policies)

12 Months Ended

Dec. 31, 2018

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Basis of Presentation

Certain prior period amounts have been reclassified to conform to the current period presentation.

Basis of Financial Statements and Use of Estimates

Inter-company balances and transactions are eliminated in consolidation.

Revenue Recognition

Performance Obligations and Transaction Price

Disaggregation of Revenue

Revenues By Type

Revenues By Segment

Share-Based Compensation

Research and Development

Costs incurred in the preliminary and post-implementation stages of MSCI’s products are expensed as incurred.

The Company had no indefinite-lived intangible assets.

Foreign Currency Translation

Derivative Instruments

Property, Equipment and Leasehold Improvements

Treasury Stock

Allowance for Doubtful Accounts

	Amount
	(in thousands)
Balance as of December 31, 2015	$	1,117
Addition to provision		1,011
Amounts written off, net of recoveries		(1,093	)
Balance as of December 31, 2016	$	1,035
Addition to provision		1,422
Amounts written off, net of recoveries		(757	)
Balance as of December 31, 2017	$	1,700
Reduction to provision		(224	)
Amounts written off, net of recoveries		(449	)
Balance as of December 31, 2018	$	1,027

Accrued Compensation

Concentrations

Recent Accounting Standards Updates

MSCI does not believe the new guidance will have a material impact on its liquidity and under its current agreements it will have no impact on its debt-covenant compliance.

Introduction and Basis of Presentation (Tables)

12 Months Ended

Dec. 31, 2018

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Changes in Allowance for Doubtful Accounts

Changes in the allowance for doubtful accounts from December 31, 2015 to December 31, 2018 were as follows:

	Amount
	(in thousands)
Balance as of December 31, 2015	$	1,117
Addition to provision		1,011
Amounts written off, net of recoveries		(1,093	)
Balance as of December 31, 2016	$	1,035
Addition to provision		1,422
Amounts written off, net of recoveries		(757	)
Balance as of December 31, 2017	$	1,700
Reduction to provision		(224	)
Amounts written off, net of recoveries		(449	)
Balance as of December 31, 2018	$	1,027

Revenue Recognition (Tables)

12 Months Ended

Dec. 31, 2018

Disaggregation of Revenue

The table that follows presents the disaggregated revenues for the periods indicated (in thousands):

	For the Year Ended December 31, 2018
	Segments
	Index		Analytics		All Other		Total
Product Types
Recurring subscriptions	$	477,612	$	474,334	$	114,590	$	1,066,536
Asset-based fees		336,565		—		—		336,565
Non-recurring		21,298		5,605		3,980		30,883
Total	$	835,475	$	479,939	$	118,570	$	1,433,984

Accounting Standards Update 2014-09 [Member]

Cumulative Impact of Adoption on Company’s Consolidated Statement of Financial Condition

Selected line items	As reported at December 31, 2017		Adjustments due to Adoption of ASC Topic 606		Adjusted as of December 31, 2017
Statement of Financial Condition
Accounts receivable	$	327,597	$	145,803	$	473,400
Income taxes payable	$	14,828	$	4,314	$	19,142
Other accrued liabilities	$	85,710	$	5,128	$	90,838
Deferred revenue	$	374,365	$	120,226	$	494,591
Retained earnings	$	1,505,204	$	16,135	$	1,521,339

Schedule of Impact of Adopting New Standard on Company's Consolidated Statement of Income and Statement of Financial Condition

The impact of adopting the new revenue standard on the Company’s Consolidated Statement of Income through the date of December 31, 2018 is as follows (in thousands):

	For the Year Ended December 31, 2018
Selected line items	As reported		Impact of Change			Without Adoption of ASC Topic 606
Statement of Income
Operating revenues	$	1,433,984	$	(6,181	)	$	1,427,803
Operating income	$	686,898	$	(6,181	)	$	680,717
Income before provision for income taxes	$	629,896	$	(6,181	)	$	623,715
Provision for income taxes	$	122,011	$	(1,236	)	$	120,775
Net income	$	507,885	$	(4,945	)	$	502,940
Earnings per basic common share	$	5.83	$	(0.06	)	$	5.77
Earnings per diluted common share	$	5.66	$	(0.06	)	$	5.60

The impact of adopting the new revenue standard on the Company’s Consolidated Statement of Financial Condition through the date of December 31, 2018 is as follows (in thousands):

	December 31, 2018
Selected line items	As reported		Impact of Change			Without Adoption of ASC Topic 606
Statement of Financial Condition
Accounts receivable	$	473,433	$	(148,209	)	$	325,224
Income taxes payable	$	16,253	$	(5,550	)	$	10,703
Other accrued liabilities	$	113,841	$	(6,078	)	$	107,763
Deferred revenue	$	537,977	$	(115,501	)	$	422,476
Retained earnings	$	1,856,951	$	(21,080	)	$	1,835,871

Schedule of Accounts Receivable and Deferred Revenue

The table that follows presents the change in accounts receivable and deferred revenue between the dates indicated (in thousands):

	December 31, 2018
	Accounts receivable		Deferred revenue
Opening (1/1/2018)	$	473,400	$	494,591
Closing (12/31/2018)		473,433		537,977
Increase/(decrease)	$	33	$	43,386

Earnings Per Common Share (Tables)

12 Months Ended

Dec. 31, 2018

Earnings Per Share [Abstract]

Computation of Basic and Diluted EPS

The following table presents the computation of basic and diluted EPS:

	Years Ended
	December 31,		December 31,		December 31,
	2018		2017		2016
(in thousands, except per share data)
Net income	$	507,885	$	303,972	$	260,855

Basic weighted average common shares outstanding		87,179		90,336		95,986
Effect of dilutive securities:
Stock options and restricted stock units		2,522		1,578		554
Diluted weighted average common shares outstanding		89,701		91,914		96,540

Earnings per basic common share	$	5.83	$	3.36	$	2.72

Earnings per diluted common share	$	5.66	$	3.31	$	2.70

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2018

Commitments And Contingencies Disclosure [Abstract]

Summary of Future Minimum Commitments Under Operating Leases

Future minimum commitments for the Company’s operating leases in place as of December 31, 2018 are as follows:

Years Ending December 31,	Amount
	(in thousands)
2019	$	25,868
2020		24,619
2021		23,452
2022		21,832
2023		21,818
Thereafter		107,800
Total	$	225,389

Schedule of Senior Unsecured Notes

The Company has issued an aggregate of $2.6 billion in senior unsecured notes (collectively, the “Senior Notes”) in the four discrete private offerings described below.

		Principal amount outstanding at		Carrying value at		Carrying value at		Fair Value at		Fair Value at
	Maturity Date	December 31, 2018		December 31, 2018		December 31, 2017		December 31, 2018		December 31, 2017
	(in thousands)
Long-term debt
5.25% senior unsecured notes due 2024	November 15, 2024	$	800,000	$	793,054	$	791,880	$	802,576	$	847,064
5.75% senior unsecured notes due 2025	August 15, 2025		800,000		793,016		791,967		807,088		858,848
4.75% senior unsecured notes due 2026	August 1, 2026		500,000		494,916		494,246		475,520		525,185
5.375% senior unsecured notes due 2027	May 15, 2027		500,000		494,516	—			489,745	—
Total debt		$	2,600,000	$	2,575,502	$	2,078,093	$	2,574,929	$	2,231,097

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28541-108399

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 505
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-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21506-112644

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
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Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
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-Topic 942
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-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
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-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644

+ Details

Property, Equipment and Leasehold Improvements (Tables)

12 Months Ended

Dec. 31, 2018

Property Plant And Equipment [Abstract]

Schedule of Property, Equipment and Leasehold Improvements

Property, equipment and leasehold improvements at December 31, 2018 and 2017 consisted of the following:

		As of
	Estimated	December 31,			December 31,
	Useful Lives	2018			2017
		(in thousands)
Computer & related equipment	2 to 5 years	$	200,414		$	200,592
Furniture & fixtures	7 years		12,033			10,591
Leasehold improvements	1 to 21 years		53,429			51,128
Work-in-process	—		10,506			3,406
Subtotal			276,382			265,717
Accumulated depreciation and amortization			(185,505	)		(171,280	)
Property, equipment and leasehold improvements, net		$	90,877		$	94,437

Goodwill and Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2018

Goodwill And Intangible Assets Disclosure [Abstract]

Schedule of Change to Company's Goodwill

The change to the Company’s goodwill was as follows:

(in thousands)	Index			Analytics				All Other			Total
Goodwill at December 31, 2016	$	1,202,448		$	302,611			$	50,791		$	1,555,850
Foreign exchange translation adjustment		2,952			—				1,819			4,771
Goodwill at December 31, 2017	$	1,205,400		$	302,611			$	52,610		$	1,560,621
Changes to goodwill		—			(11,635	)	⁽¹⁾		—			(11,635	)
Foreign exchange translation adjustment		(1,996	)		—				(1,229	)		(3,225	)
Goodwill at December 31, 2018	$	1,203,404		$	290,976			$	51,381		$	1,545,761

⁽¹⁾	Reflects the $2.9 million and $8.7 million impact of the Financial Engineering Associates, Inc. (“FEA”) and Investor Force Holdings, Inc. (“InvestorForce”) divestitures, respectively. See Note 12, “Divestitures” for further information regarding the FEA and InvestorForce divestitures.

Schedule of Gross Carrying and Accumulated Amortization Amounts Related to Company's Identifiable Intangible Assets

The gross carrying and accumulated amortization amounts related to the Company’s identifiable intangible assets were as follows:

		As of
	Estimated	December 31,			December 31,
	Useful Lives	2018			2017
		(in thousands)
Gross intangible assets:
Customer relationships⁽¹⁾	5 to 21 years	$	356,700		$	361,199
Trademarks/trade names⁽¹⁾	5 to 21.5 years		208,320			223,382
Technology/software^{(1), (2)}	3 to 8.5 years		238,692			225,407
Proprietary data	13 years		28,627			28,627
Subtotal			832,339			838,615
Foreign exchange translation adjustment			(9,569	)		(9,167	)
Total gross intangible assets		$	822,770		$	829,448
Accumulated amortization:
Customer relationships⁽¹⁾		$	(209,867	)	$	(189,100	)
Trademarks/trade names⁽¹⁾			(123,345	)		(116,691	)
Technology/software^{(1), (2)}			(198,974	)		(193,095	)
Proprietary data			(12,197	)		(10,352	)
Subtotal			(544,383	)		(509,238	)
Foreign exchange translation adjustment			2,416			1,626
Total accumulated amortization		$	(541,967	)	$	(507,612	)
Net intangible assets:
Customer relationships		$	146,833		$	172,099
Trademarks/trade names			84,975			106,691
Technology/software			39,718			32,312
Proprietary data			16,430			18,275
Subtotal			287,956			329,377
Foreign exchange translation adjustment			(7,153	)		(7,541	)
Total net intangible assets		$	280,803		$	321,836

⁽¹⁾ A portion of the change reflects the impact of the InvestorForce divestiture. See Note 12, “Divestitures” for further information regarding the InvestorForce divestiture.

⁽²⁾ A portion of the change reflects the impact of the FEA divestiture. See Note 12, “Divestitures” for further information regarding the FEA divestiture.

Estimated Amortization Expense for Succeeding Years

Estimated amortization expense for succeeding years is presented below:

Years Ending December 31,	Amortization Expense
	(in thousands)
2019	$	47,886
2020		46,339
2021		42,286
2022		35,819
2023		32,778
Thereafter		75,695
Total	$	280,803

Shareholders' Equity (Deficit) (Tables)

12 Months Ended

Dec. 31, 2018

Equity [Abstract]

Schedule of Company's Common Stock Repurchases Pursuant to Open Market Repurchases

The following table provides information with respect to repurchases of the Company’s common stock pursuant to open market repurchases:

Year Ended	Average Price Paid Per Share		Total Number of Shares Repurchased		Dollar Value of Shares Repurchased
	(in thousands, except per share data)
December 31, 2018	$	148.34		6,236	$	924,989
December 31, 2017	$	87.96		1,556	$	136,899
December 31, 2016	$	73.71		10,303	$	759,427

Schedule of Cash Dividends Declared and Distributed Per Common Share

The following table presents cash dividends declared and distributed per common share for the periods indicated:

	Dividends
	Per Share		Declared		Distributed		Deferred
2018	(in thousands, except per share data)
Three Months Ended March 31,	$	0.38	$	34,848	$	34,900	$	(52	)
Three Months Ended June 30,		0.38		34,254		33,935		319
Three Months Ended September 30,		0.58		52,264		51,764		500
Three Months Ended December 31,		0.58		50,907		50,434		473
Year Ended December 31,	$	1.92	$	172,273	$	171,033	$	1,240
2017
Three Months Ended March 31,	$	0.28	$	25,769	$	25,500	$	269
Three Months Ended June 30,		0.28		25,710		25,444		266
Three Months Ended September 30,		0.38		34,768		34,403		365
Three Months Ended December 31,		0.38		34,745		34,448		297
Year Ended December 31,	$	1.32	$	120,992	$	119,795	$	1,197
2016
Three Months Ended March 31,	$	0.22	$	22,046	$	21,889	$	157
Three Months Ended June 30,	0.22			21,588		21,391		197
Three Months Ended September 30,	0.28			26,936		26,680		256
Three Months Ended December 31,	0.28			26,524		26,304		220
Year Ended December 31,	$	1.00	$	97,094	$	96,264	$	830

Summary of Activity Related to Shares of Common Stock Issued and Repurchased

The following table presents activity related to shares of common stock issued and repurchased for the periods indicated:

	Common		Treasury			Common Stock
	Stock Issued		Stock			Outstanding
Balance At December 31, 2015		128,200,189		(27,187,041	)		101,013,148
Dividend payable/paid		892		(472	)		420
Common stock issued and exercise of stock options		788,304		—			788,304
Shares withheld for tax withholding and exercises		—		(219,921	)		(219,921	)
Shares repurchased under stock repurchase programs		—		(10,303,047	)		(10,303,047	)
Shares issued to directors		6,959		(6,273	)		686
Balance At December 31, 2016		128,996,344		(37,716,754	)		91,279,590
Dividend payable/paid		684		(528	)		156
Common stock issued and exercise of stock options		538,448		—			538,448
Shares withheld for tax withholding and exercises		—		(157,667	)		(157,667	)
Shares repurchased under stock repurchase programs		—		(1,556,313	)		(1,556,313	)
Shares issued to directors		8,380		(7,709	)		671
Balance At December 31, 2017		129,543,856		(39,438,971	)		90,104,885
Dividend payable/paid		734		(579	)		155
Common stock issued and exercise of stock options		479,277		—			479,277
Shares withheld for tax withholding and exercises		—		(174,991	)		(174,991	)
Shares repurchased under stock repurchase programs		—		(6,235,629	)		(6,235,629	)
Shares issued to directors		6,059		(5,618	)		441
Balance At December 31, 2018		130,029,926		(45,855,788	)		84,174,138

Components of Share-Based Compensation Expense

The components of share-based compensation expense related to the awards to Company employees and directors who are not employees of the Company are presented below:

	Years Ended
	December 31,		December 31,		December 31,
(in thousands)	2018		2017		2016
Share-based Awards	$	40,563	$	37,921	$	32,525

Summary of Share-based Compensation Expense

The following table presents the amount of share-based compensation expense by category for the periods indicated:

	Years Ended
	December 31,		December 31,		December 31,
(in thousands)	2018		2017		2016
Cost of revenues	$	10,334	$	9,707	$	7,971
Selling and marketing		12,851		11,355		9,526
Research and development		4,175		3,477		2,970
General and administrative		13,203		13,382		12,058
Total share-based compensation expense	$	40,563	$	37,921	$	32,525

Summary of Vested and Unvested Share-Based Awards Activity

The following table presents activity concerning the Company’s vested and unvested Share-based Awards applicable to its employees (share data in thousands) for the period indicated:

				Weighted
				Average
				Grant
	Number of			Date Fair
For the Year Ended December 31, 2018	Shares			Value
Vested and unvested Share-based Awards at December 31, 2017		1,419		$	68.50
Granted		332		$	117.64
Conversion to common stock		(451	)	$	65.40
Canceled		(12	)	$	87.17
Vested and unvested Share-based Awards at December 31, 2018 ⁽¹⁾		1,288		$	82.09

⁽¹⁾	As of December 31, 2018, 1,261 Share-based Awards, with a weighted average price of $81.51, were vested or expected to vest.

Summary of Unvested Share-Based Awards Activity

The following table presents activity concerning the Company’s unvested Share-based Awards related to its employees (share data in thousands):

				Weighted
				Average
				Grant
	Number of			Date Fair
For the Year Ended December 31, 2018	Shares			Value
Unvested Share-based Awards at December 31, 2017		1,166		$	69.96
Granted		280		$	124.66
Vested		(332	)	$	68.41
Canceled		(12	)	$	87.17
Unvested Share-based Awards at December 31, 2018		1,102		$	84.14

Unvested Share-based Awards expected to vest		1,075		$	83.51

Summary of Stock Options Activity

						Weighted
				Weighted		Average
	Number			Average		Remaining		Aggregated
	of			Exercise		Life		Intrinsic
For the Year Ended December 31, 2018	Options			Price		(Years)		Value
Options outstanding at December 31, 2017		145		$	26.47		2.11	$	14,519
Granted or assumed		—		$	—	N/A		N/A
Forfeited		—		$	—	N/A		N/A
Conversion to common stock		(33	)	$	18.14	N/A		N/A
Options outstanding and exercisable at December 31, 2018		112		$	28.96	1.28		$	13,239

Summary of Stock Options Outstanding and Exercisable by Exercise Price Range

As of December 31, 2018		Options Outstanding
				Weighted		Average
				Average		Remaining		Aggregate
		Number		Exercise		Life		Intrinsic
Range of Exercise Prices		Outstanding		Price		(Years)		Value
$15.18 to $16.48			12	$	16.48		0.15	$	1,521
$20.45 to $24.11			14	$	20.45		0.65	$	1,798
$	25.64		36	$	25.64		0.96	$	4,409
$	36.70		50	$	36.70		1.95	$	5,511
Total			112					$	13,239

Reclassifications out of Accumulated Other Comprehensive Income (Loss) (Tables)

12 Months Ended

Dec. 31, 2018

Statement Of Income And Comprehensive Income [Abstract]

Schedule of Reclassifications out of Accumulated Other Comprehensive Income (Loss)

Reclassifications Out of Accumulated Other Comprehensive Income (Loss) ⁽¹⁾


Details about Accumulated Other	Amount Reclassified from Accumulated									Affected Line Item in the
Comprehensive Income (Loss) Components	Other Comprehensive Income (Loss)									Consolidated Statements of Income
	Years Ended
	December 31,			December 31,			December 31,
	2018			2017			2016
				(in thousands)
Defined benefit pension plans
Amount recognized as a component of net periodic benefit expense for curtailments and settlements	$	(222	)	$	(281	)	$	(261	)
Income Taxes	54			77			73			Provision for income taxes
Total reclassifications for the period, net of tax	$	(168	)	$	(204	)	$	(188	)

⁽¹⁾	Amounts in parentheses indicate expenses or losses moved to the Consolidated Statements of Income.

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Summary of Provision for Income Taxes (Benefits) by Taxing Jurisdiction

The provision for income taxes (benefits) by taxing jurisdiction consisted of:

	Years Ended
	December 31,			December 31,			December 31,
	2018			2017			2016
	(in thousands)
Current
U.S. federal	$	51,316		$	133,250		$	93,071
U.S. state and local		31,680			16,312			16,363
Non U.S.		39,795			32,267			32,616
		122,791			181,829			142,050
Deferred
U.S. federal		(1,406	)		(12,502	)		(13,010	)
U.S. state and local		5,566			(2,119	)		(2,235	)
Non U.S.		(4,940	)		(4,281	)		(1,722	)
		(780	)		(18,902	)		(16,967	)

Provision for income taxes	$	122,011		$	162,927		$	125,083

Reconciliation of U.S. Federal Statutory Income Tax Rate to the Effective Tax Rate

The following table reconciles the U.S. federal statutory income tax rate to the effective income tax rate:

	Years Ended
	December 31,			December 31,			December 31,
	2018			2017			2016
U.S. federal statutory income tax rate		21.00	%		35.00	%		35.00	%
U.S. state and local income taxes, net of U.S. federal income tax benefits		4.66	%		1.84	%		2.38	%
Change in tax rates applicable to non-U.S. earnings		(2.20	%)		(7.60	%)		(3.73	%)
Domestic tax credits and incentives		(0.30	%)		(0.24	%)		(0.26	%)
Net tax charge related to Tax Reform		(1.78	%)		7.40	%		—	%
Valuation allowance		(1.41	%)		—	%		—	%
Excess Stock Based Compensation		(1.14	%)		(1.25	%)		—	%
Other		0.54	%		(0.25	%)		(0.98	%)
Effective income tax rate		19.37	%		34.90	%		32.41	%

Significant Components of Deferred Tax Assets and Liabilities

Significant components of the Company’s deferred tax assets and liabilities as of December 31, 2018 and 2017, were as follows:

	As of
	December 31,			December 31,
	2018			2017
	(in thousands)
Deferred tax assets:
Employee compensation and benefit plans	$	19,698		$	19,646
Deferred rent		5,392			5,308
Pension		2,466			1,520
Unearned revenue		—			853
Loss carryforwards - non-current		2,941			18,105
Other		—			1,435
Subtotal		30,497			46,867
Less: valuation allowance		(632	)		(11,575	)
Total deferred tax assets	$	29,865		$	35,292
Deferred tax liabilities:
Intangible assets	$	(65,538	)	$	(73,634	)
Unearned revenue		(1,170	)		—
Unremitted foreign earnings		(12,872	)		(16,108	)
Property, equipment and leasehold improvements, net		(16,369	)		(11,564	)
Other		(1,021	)		—
Total deferred tax liabilities	$	(96,970	)	$	(101,306	)
Net deferred tax liabilities	$	(67,105	)	$	(66,014	)

Summary of Deferred Tax Asset Valuation Allowance

The following table presents changes in the Company’s deferred tax asset valuation allowance for the periods indicated:

	Years Ended
	December 31,			December 31,			December 31,
	2018			2017			2016
	(in thousands)
Beginning balance	$	11,575		$	17,807		$	21,052
Additions charged to cost and expenses		—			324			1,862
Additions charged to other accounts		—			—			—
Deductions		(10,943	)		(6,556	)		(5,107	)
Ending balance	$	632		$	11,575		$	17,807

Summary of Components of Income Before Provision for Income Taxes

The following table presents the components of income before provision for income taxes generated by domestic or foreign operations for the periods indicated:

	Years Ended
	December 31,		December 31,		December 31,
	2018		2017		2016
	(in thousands)
Domestic	$	399,000	$	283,779	$	263,536
Foreign ⁽¹⁾		230,896		183,120		122,402
Total income before provision for income taxes	$	629,896	$	466,899	$	385,938

⁽¹⁾	Foreign income before provision for income taxes is defined as income generated from operations located outside the U.S., which includes income from foreign branches of U.S. companies.

Reconciliation of Unrecognized Tax Benefits

	Years Ended
	December 31,			December 31,			December 31,
Gross unrecognized tax benefits	2018			2017			2016
(in thousands)
Beginning balance	$	10,022		$	7,936		$	8,692
Increases based on tax positions related to the current period		3,928			3,389			575
Increases based on tax positions related to prior periods		1,892			519			135
Decreases based on tax positions related to prior periods		(297	)		(6	)		(3	)
Decreases related to settlements with taxing authorities		—			(1,152	)		(1,463	)
Decreases related to a lapse of applicable statute of limitations		(1,454	)		(664	)		—
Ending balance	$	14,091		$	10,022		$	7,936

Segment Information (Tables)

12 Months Ended

Dec. 31, 2018

Segment Reporting [Abstract]

Operating Revenues by Reportable Segment

The following table presents operating revenues by reportable segment for the periods indicated:

		Years Ended
		December 31,		December 31,		December 31,
		2018		2017		2016
	(in thousands)
Operating revenues
Index		$	835,475	$	718,959	$	613,551
Analytics			479,939		458,269		448,353
All Other			118,570		96,944		88,765
Total		$	1,433,984	$	1,274,172	$	1,150,669

Segment Profitability and Reconciliation to Net Income

The following table presents segment profitability and a reconciliation to net income for the periods indicated:

		Years Ended
		December 31,		December 31,		December 31,
		2018		2017		2016
	(in thousands)
Index Adjusted EBITDA		$	607,853	$	522,241	$	431,478
Analytics Adjusted EBITDA			143,645		125,624		128,507
All Other Adjusted EBITDA			20,935		11,892		9,472
Total operating segment profitability			772,433		659,757		569,457
Amortization of intangible assets			54,189		44,547		47,033
Depreciation and amortization of property, equipment and leasehold improvements			31,346		35,440		34,320
Operating income			686,898		579,770		488,104
Other expense (income), net			57,002		112,871		102,166
Provision for income taxes			122,011		162,927		125,083
Net income		$	507,885	$	303,972	$	260,855

Revenue by Geographic Area

Revenue by geography is based on the shipping address of the ultimate customer utilizing the product. The following table presents revenue by geographic area for the periods indicated:

	Years Ended
	December 31,		December 31,		December 31,
(in thousands)	2018			2017	2016
Operating revenues
Americas:
United States	$	662,345	$	622,132	$	556,777
Other		58,065		48,139		45,185
Total Americas		720,410		670,271		601,962
Europe, the Middle East and Africa ("EMEA"):
United Kingdom		214,204		193,831		175,749
Other		293,252		250,267		229,010
Total EMEA		507,456		444,098		404,759
Asia & Australia:
Japan		67,100		54,351		52,161
Other		139,018		105,452		91,787
Total Asia & Australia		206,118		159,803		143,948
Total	$	1,433,984	$	1,274,172	$	1,150,669

Long-Lived Assets by Geographic Area

	As of
	December 31,		December 31,
	2018		2017
	(in thousands)
Long-lived assets
Americas:
United States	$	1,803,321	$	1,847,605
Other		6,560		1,685
Total Americas		1,809,881		1,849,290
EMEA:
United Kingdom		80,039		94,782
Other		19,369		22,394
Total EMEA		99,408		117,176
Asia & Australia:
Japan		411		432
Other		7,741		9,996
Total Asia & Australia		8,152		10,428
Total	$	1,917,441	$	1,976,894

Quarterly Results of Operations (Tables)

12 Months Ended

Dec. 31, 2018

Quarterly Financial Information Disclosure [Abstract]

Summary of Quarterly Results of Operations

	2018												2017
	First			Second			Third			Fourth			First			Second			Third			Fourth
	Quarter			Quarter			Quarter			Quarter			Quarter			Quarter			Quarter			Quarter
	(in thousands, except per share data)
Operating revenues	$	351,316		$	363,046		$	357,934		$	361,688		$	301,207		$	316,089		$	322,097		$	334,779
Cost of revenues		71,304			71,368			70,906			73,757			67,463			68,538			68,433			69,247
Selling and marketing		46,409			47,416			46,149			52,949			42,972			41,550			44,873			47,726
Research and development		20,707			19,801			20,591			20,312			18,970			18,196			17,974			20,709
General and administrative		26,187			24,036			24,751			24,908			20,981			21,424			22,079			23,280
Amortization of intangible assets		11,338			19,537			11,681			11,633			11,251			11,122			10,614			11,560
Depreciation and amortization of property, equipment and leasehold improvements		8,205			7,377			7,453			8,311			8,838			9,159			9,325			8,118
Total operating expenses		184,150			189,535			181,531			191,870			170,475			169,989			173,298			180,640
Operating income		167,166			173,511			176,403			169,818			130,732			146,100			148,799			154,139
Interest income		(2,770	)		(4,281	)		(6,522	)		(6,096	)		(932	)		(1,310	)		(1,835	)		(2,237	)
Interest expense		29,560			31,761			35,902			35,891			29,024			29,027			29,020			29,027
Other expense (income)		938			(10,292	)		177			(47,266	)		1,015			872			811			389
Other expense (income), net		27,728			17,188			29,557			(17,471	)		29,107			28,589			27,996			27,179
Income before provision for income taxes		139,438			156,323			146,846			187,289			101,625			117,511			120,803			126,960
Provision for income taxes		24,346			39,494			23,014			35,157			28,674			36,245			35,650			62,358
Net income	$	115,092		$	116,829		$	123,832		$	152,132		$	72,951		$	81,266		$	85,153		$	64,602

Earnings per basic common share	$	1.28		$	1.31		$	1.39		$	1.75		$	0.80		$	0.90		$	0.94		$	0.72

Earnings per diluted common share	$	1.24		$	1.28		$	1.36		$	1.70		$	0.80		$	0.89		$	0.93		$	0.70

Weighted average shares outstanding used in computing per share data
Basic		90,075			89,112			88,796			86,968			90,708			90,404			90,112			90,130
Diluted		92,587			91,586			91,372			89,495			91,624			91,708			91,868			92,467

Introduction and Basis of Presentation - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2018 USD ($) Customer	Dec. 31, 2017 USD ($) Customer	Dec. 31, 2016 USD ($) Customer
Introduction And Basis Of Presentation [Line Items]
Minimum percentage of voting stock for consolidation	50.00%
Variable interest entities or investments	$ 0
Capitalized software development costs	18,704,000	$ 15,640,000	$ 10,344,000
Impairment of goodwill	0	$ 0	$ 0
Remaining unamortized value written off	$ 7,900,000
Sales Revenue, Services, Net \| Customer Concentration Risk
Introduction And Basis Of Presentation [Line Items]
Number of major customers accounted for 10.0% or more of revenues \| Customer			0
Sales Revenue, Services, Net \| Customer Concentration Risk \| Blackrock Inc [Member]
Introduction And Basis Of Presentation [Line Items]
Percentage of operating revenues accounted for by major customer	11.90%	11.50%
Sales Revenue, Services, Net \| Index [Member] \| Customer Concentration Risk \| Blackrock Inc [Member]
Introduction And Basis Of Presentation [Line Items]
Percentage of operating revenues accounted for by major customer	20.10%	20.00%	17.30%
Sales Revenue, Services, Net \| Analytics [Member] \| Customer Concentration Risk
Introduction And Basis Of Presentation [Line Items]
Number of major customers accounted for 10.0% or more of revenues \| Customer	0	0	0
Sales Revenue, Services, Net \| All Other [Member] \| Customer Concentration Risk
Introduction And Basis Of Presentation [Line Items]
Number of major customers accounted for 10.0% or more of revenues \| Customer	0	0	0
Minimum [Member] \| Software and Software Development Costs [Member]
Introduction And Basis Of Presentation [Line Items]
Estimates of useful lives	3 years
Maximum [Member] \| Software and Software Development Costs [Member]
Introduction And Basis Of Presentation [Line Items]
Estimates of useful lives	5 years

Introduction and Basis of Presentation - Changes in Allowance for Doubtful Accounts (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Receivables [Abstract]
Balance at beginning of year	$ 1,700	$ 1,035	$ 1,117
Addition to provision		1,422	1,011
Reduction to provision	(224)
Amounts written off, net of recoveries	(449)	(757)	(1,093)
Balance at ending of year	$ 1,027	$ 1,700	$ 1,035

Recent Accounting Standards Updates - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Non-service related pension costs	$ 0.6
Subsequent Events [Member] \| Minimum [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total operating leases ROU assets		$ 170.0
Total operating Lease Liability		190.0
Subsequent Events [Member] \| Maximum [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total operating leases ROU assets		190.0
Total operating Lease Liability		$ 210.0

Revenue Recognition - Cumulative Impact of Adoption on Company's Consolidated Statement of Financial Condition (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Accounts receivable	$ 473,433		$ 327,597
Income taxes payable	16,253		14,828
Other accrued liabilities	113,841		85,710
Deferred revenue	537,977		374,365
Retained earnings	1,856,951		1,505,204
Accounting Standards Update 2014-09 [Member]
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Accounts receivable		$ 473,400	473,400
Income taxes payable			19,142
Other accrued liabilities			90,838
Deferred revenue		$ 494,591	494,591
Retained earnings			1,521,339
Accounting Standards Update 2014-09 [Member] \| Adjustments due to Adoption of ASC Topic 606 [Member]
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Accounts receivable	(148,209)		145,803
Income taxes payable	(5,550)		4,314
Other accrued liabilities	(6,078)		5,128
Deferred revenue	(115,501)		120,226
Retained earnings	$ (21,080)		$ 16,135

Revenue Recognition - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($)
Revenue Recognition [Line Items]
Revenue recognized during period included in deferred revenue	$ 478.8
Revenue, performance obligations and revenue recognition, description	The majority of MSCI’s contracts have a duration of one year or less and, accordingly, revenue associated with these performance obligations will be recognized within 12 months.
Remaining performance obligations	$ 483.4
Accounting Standards Update 2014-09 [Member] \| Adjustments due to Adoption of ASC Topic 606 [Member]
Revenue Recognition [Line Items]
Increase to accounts receivable, deferred revenue and other accrued liabilities	$ 135.5

Revenue Recognition - Schedule of Impact of Adopting New Revenue Standard on Company's Consolidated Statement of Income (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Income
Operating revenues	$ 361,688	$ 357,934	$ 363,046	$ 351,316	$ 334,779	$ 322,097	$ 316,089	$ 301,207	$ 1,433,984	$ 1,274,172	$ 1,150,669
Operating income	169,818	176,403	173,511	167,166	154,139	148,799	146,100	130,732	686,898	579,770	488,104
Income before provision for income taxes	187,289	146,846	156,323	139,438	126,960	120,803	117,511	101,625	629,896	466,899	385,938
Provision for income taxes	35,157	23,014	39,494	24,346	62,358	35,650	36,245	28,674	122,011	162,927	125,083
Net income	$ 152,132	$ 123,832	$ 116,829	$ 115,092	$ 64,602	$ 85,153	$ 81,266	$ 72,951	$ 507,885	$ 303,972	$ 260,855
Earnings per basic common share	$ 1.75	$ 1.39	$ 1.31	$ 1.28	$ 0.72	$ 0.94	$ 0.90	$ 0.80	$ 5.83	$ 3.36	$ 2.72
Earnings per diluted common share	$ 1.70	$ 1.36	$ 1.28	$ 1.24	$ 0.70	$ 0.93	$ 0.89	$ 0.80	$ 5.66	$ 3.31	$ 2.70
Accounting Standards Update 2014-09 [Member] \| Impact of Change [Member]
Statement of Income
Operating revenues									$ (6,181)
Operating income									(6,181)
Income before provision for income taxes									(6,181)
Provision for income taxes									(1,236)
Net income									$ (4,945)
Earnings per basic common share									$ (0.06)
Earnings per diluted common share									$ (0.06)
Accounting Standards Update 2014-09 [Member] \| Without Adoption of ASC Topic 606 [Member]
Statement of Income
Operating revenues									$ 1,427,803
Operating income									680,717
Income before provision for income taxes									623,715
Provision for income taxes									120,775
Net income									$ 502,940
Earnings per basic common share									$ 5.77
Earnings per diluted common share									$ 5.60

Revenue Recognition - Schedule of Impact of Adopting New Revenue Standard on Company's Consolidated Statement of Financial Condition (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Statement of Financial Condition
Accounts receivable	$ 473,433		$ 327,597
Income taxes payable	16,253		14,828
Other accrued liabilities	113,841		85,710
Deferred revenue	537,977		374,365
Retained earnings	1,856,951		1,505,204
Accounting Standards Update 2014-09 [Member]
Statement of Financial Condition
Accounts receivable		$ 473,400	473,400
Income taxes payable			19,142
Other accrued liabilities			90,838
Deferred revenue		$ 494,591	494,591
Retained earnings			1,521,339
Accounting Standards Update 2014-09 [Member] \| Impact of Change [Member]
Statement of Financial Condition
Accounts receivable	(148,209)		145,803
Income taxes payable	(5,550)		4,314
Other accrued liabilities	(6,078)		5,128
Deferred revenue	(115,501)		120,226
Retained earnings	(21,080)		$ 16,135
Accounting Standards Update 2014-09 [Member] \| Without Adoption of ASC Topic 606 [Member]
Statement of Financial Condition
Accounts receivable	325,224
Income taxes payable	10,703
Other accrued liabilities	107,763
Deferred revenue	422,476
Retained earnings	$ 1,835,871

Revenue Recognition - Disaggregation of Revenue (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation Of Revenue [Line Items]
Operating revenues	$ 361,688	$ 357,934	$ 363,046	$ 351,316	$ 334,779	$ 322,097	$ 316,089	$ 301,207	$ 1,433,984	$ 1,274,172	$ 1,150,669
Index [Member]
Disaggregation Of Revenue [Line Items]
Operating revenues									835,475	718,959	613,551
Analytics [Member]
Disaggregation Of Revenue [Line Items]
Operating revenues									479,939	458,269	448,353
All Other [Member]
Disaggregation Of Revenue [Line Items]
Operating revenues									118,570	$ 96,944	$ 88,765
Recurring Subscriptions [Member]
Disaggregation Of Revenue [Line Items]
Operating revenues									1,066,536
Recurring Subscriptions [Member] \| Index [Member]
Disaggregation Of Revenue [Line Items]
Operating revenues									477,612
Recurring Subscriptions [Member] \| Analytics [Member]
Disaggregation Of Revenue [Line Items]
Operating revenues									474,334
Recurring Subscriptions [Member] \| All Other [Member]
Disaggregation Of Revenue [Line Items]
Operating revenues									114,590
Asset-based Fees [Member]
Disaggregation Of Revenue [Line Items]
Operating revenues									336,565
Asset-based Fees [Member] \| Index [Member]
Disaggregation Of Revenue [Line Items]
Operating revenues									336,565
Non-recurring [Member]
Disaggregation Of Revenue [Line Items]
Operating revenues									30,883
Non-recurring [Member] \| Index [Member]
Disaggregation Of Revenue [Line Items]
Operating revenues									21,298
Non-recurring [Member] \| Analytics [Member]
Disaggregation Of Revenue [Line Items]
Operating revenues									5,605
Non-recurring [Member] \| All Other [Member]
Disaggregation Of Revenue [Line Items]
Operating revenues									$ 3,980

Revenue Recognition - Schedule of Accounts Receivable and Deferred Revenue (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2018
Revenue Recognition [Line Items]
Accounts receivable	$ 473,433	$ 327,597
Accounts receivable, Increase/(decrease)	153,942	105,593	$ 18,494
Deferred revenue	537,977	374,365
Deferred revenue, Increase/(decrease)	185,077	38,555	$ 21,809
Accounting Standards Update 2014-09 [Member]
Revenue Recognition [Line Items]
Accounts receivable		473,400		$ 473,400
Deferred revenue		494,591		$ 494,591
Accounting Standards Update 2014-09 [Member] \| Adjustments due to Adoption of ASC Topic 606 [Member]
Revenue Recognition [Line Items]
Accounts receivable	(148,209)	145,803
Accounts receivable, Increase/(decrease)	33
Deferred revenue	(115,501)	$ 120,226
Deferred revenue, Increase/(decrease)	$ 43,386

Revenue Recognition - Additional Information (Detail 1) $ in Millions	Dec. 31, 2018 USD ($)
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Remaining performance obligations	$ 483.4
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2019-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Remaining performance obligations	$ 254.2
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	12 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2020-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Remaining performance obligations	$ 137.9
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	12 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2021-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Remaining performance obligations	$ 56.2
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	12 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2022-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Remaining performance obligations	$ 35.1
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period

Earnings Per Common Share - Additional Information (Detail) - shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share [Abstract]
Anti-dilutive securities excluded from the calculation of diluted EPS	2,704	987	398

Earnings Per Common Share - Computation of Basic and Diluted EPS (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share [Abstract]
Net income	$ 152,132	$ 123,832	$ 116,829	$ 115,092	$ 64,602	$ 85,153	$ 81,266	$ 72,951	$ 507,885	$ 303,972	$ 260,855
Basic weighted average common shares outstanding	86,968	88,796	89,112	90,075	90,130	90,112	90,404	90,708	87,179	90,336	95,986
Effect of dilutive securities:
Stock options and restricted stock units									2,522	1,578	554
Diluted weighted average common shares outstanding	89,495	91,372	91,586	92,587	92,467	91,868	91,708	91,624	89,701	91,914	96,540
Earnings per basic common share	$ 1.75	$ 1.39	$ 1.31	$ 1.28	$ 0.72	$ 0.94	$ 0.90	$ 0.80	$ 5.83	$ 3.36	$ 2.72
Earnings per diluted common share	$ 1.70	$ 1.36	$ 1.28	$ 1.24	$ 0.70	$ 0.93	$ 0.89	$ 0.80	$ 5.66	$ 3.31	$ 2.70

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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+ Details

- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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+ Details

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Commitments and Contingencies - Additional Information (Detail) - USD ($)				12 Months Ended
	May 18, 2018	May 15, 2018	Aug. 04, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Nov. 20, 2014
Schedule Of Commitments And Contingencies [Line Items]
Annual rent expense				$ 25,300,000	$ 24,200,000	$ 24,200,000
Debt instrument principal amount				2,600,000,000
Prepaid and Other Assets [Member]
Schedule Of Commitments And Contingencies [Line Items]
Deferred financing fees				400,000
Other Non-Current Assets [Member]
Schedule Of Commitments And Contingencies [Line Items]
Deferred financing fees				1,400,000
Long-term Debt [Member]
Schedule Of Commitments And Contingencies [Line Items]
Deferred financing fees				$ 24,500,000
Revolving Credit Agreement [Member]
Schedule Of Commitments And Contingencies [Line Items]
Revolving credit facility, maximum borrowing		$ 250,000,000	$ 220,000,000				$ 200,000,000
Revolving credit agreement, term				5 years
Revolving credit agreement, extended term		1 year	1 year
5.250% Senior Unsecured Notes Due 2024 [Member]
Schedule Of Commitments And Contingencies [Line Items]
Debt instrument principal amount				$ 800,000,000
Debt instrument interest rate				5.25%
Maturity date				Nov. 15, 2024
Redemption description				At any time prior to November 15, 2019, the Company may redeem all or part of the 2024 Senior Notes upon not less than 30 nor more than 60 days’ prior notice at a redemption price equal to the sum of (i) 100% of the principal amount thereof, plus (ii) a make-whole premium as of the date of redemption, plus (iii) accrued and unpaid interest and additional interest, if any, thereon, to the date of redemption.
5.75% Senior Unsecured Notes Due 2025 [Member]
Schedule Of Commitments And Contingencies [Line Items]
Debt instrument principal amount				$ 800,000,000
Debt instrument interest rate				5.75%
Maturity date				Aug. 15, 2025
Redemption description				At any time prior to August 15, 2020, the Company may redeem all or part of the 2025 Senior Notes upon not less than 30 nor more than 60 days’ prior notice at a redemption price equal to the sum of (i) 100% of the principal amount thereof, plus (ii) a make-whole premium as of the date of redemption, plus (iii) accrued and unpaid interest and additional interest, if any, thereon, to the date of redemption.
4.75% Senior Unsecured Notes Due 2026 [Member]
Schedule Of Commitments And Contingencies [Line Items]
Debt instrument principal amount				$ 500,000,000
Debt instrument interest rate				4.75%
Maturity date				Aug. 01, 2026
Redemption description				At any time prior to August 1, 2021, the Company may redeem all or part of the 2026 Senior Notes upon not less than 30 nor more than 60 days’ prior notice at a redemption price equal to the sum of (i) 100% of the principal amount thereof, plus (ii) a make-whole premium as of the date of redemption, plus (iii) accrued and unpaid interest and additional interest, if any, thereon, to the date of redemption.
Percentage of aggregate principal amount redeemed				35.00%
Redemption price				104.75%
5.375% Senior Unsecured Notes Due 2027 [Member]
Schedule Of Commitments And Contingencies [Line Items]
Debt instrument principal amount	$ 500,000,000			$ 500,000,000
Debt instrument interest rate	5.375%			5.375%
Maturity date				May 15, 2027
Redemption description				At any time prior to May 15, 2022, the Company may redeem all or part of the 2027 Senior Notes upon not less than 30 nor more than 60 days’ prior notice at a redemption price equal to the sum of (i) 100% of the principal amount thereof, plus (ii) a make-whole premium as of the date of redemption, plus (iii) accrued and unpaid interest and additional interest, if any, thereon, to the date of redemption.
Percentage of aggregate principal amount redeemed				35.00%
Redemption price				105.375%
Net proceeds from borrowing	$ 495,000,000
Senior Notes [Member]
Schedule Of Commitments And Contingencies [Line Items]
Debt instrument principal amount				$ 2,600,000,000
Senior Notes and Revolving Credit Facility [Member]
Schedule Of Commitments And Contingencies [Line Items]
Deferred financing fees				$ 26,300,000

Commitments and Contingencies - Summary of Future Minimum Commitments Under Operating Leases (Detail) $ in Thousands	Dec. 31, 2018 USD ($)
Commitments And Contingencies Disclosure [Abstract]
2019	$ 25,868
2020	24,619
2021	23,452
2022	21,832
2023	21,818
Thereafter	107,800
Total	$ 225,389

Commitments and Contingencies - Schedule of Senior Unsecured Notes (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2018	May 18, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Principal amount outstanding	$ 2,600,000,000
Carrying value	2,575,502,000		$ 2,078,093,000
Fair Value	$ 2,574,929,000		2,231,097,000
5.25% Senior Unsecured Notes Due 2024 [Member]
Debt Instrument [Line Items]
Maturity Date	Nov. 15, 2024
Principal amount outstanding	$ 800,000,000
Carrying value	793,054,000		791,880,000
Fair Value	$ 802,576,000		847,064,000
5.75% Senior Unsecured Notes Due 2025 [Member]
Debt Instrument [Line Items]
Maturity Date	Aug. 15, 2025
Principal amount outstanding	$ 800,000,000
Carrying value	793,016,000		791,967,000
Fair Value	$ 807,088,000		858,848,000
4.75% Senior Unsecured Notes Due 2026 [Member]
Debt Instrument [Line Items]
Maturity Date	Aug. 01, 2026
Principal amount outstanding	$ 500,000,000
Carrying value	494,916,000		494,246,000
Fair Value	$ 475,520,000		$ 525,185,000
5.375% Senior Unsecured Notes Due 2027 [Member]
Debt Instrument [Line Items]
Maturity Date	May 15, 2027
Principal amount outstanding	$ 500,000,000	$ 500,000,000
Carrying value	494,516,000
Fair Value	$ 489,745,000

Commitments and Contingencies - Schedule of Senior Unsecured Notes (Parenthetical) (Detail)	Dec. 31, 2018	May 18, 2018
5.25% Senior Unsecured Notes Due 2024 [Member]
Debt Instrument [Line Items]
Debt instrument interest rate	5.25%
5.75% Senior Unsecured Notes Due 2025 [Member]
Debt Instrument [Line Items]
Debt instrument interest rate	5.75%
4.75% Senior Unsecured Notes Due 2026 [Member]
Debt Instrument [Line Items]
Debt instrument interest rate	4.75%
5.375% Senior Unsecured Notes Due 2027 [Member]
Debt Instrument [Line Items]
Debt instrument interest rate	5.375%	5.375%

Property, Equipment and Leasehold Improvements - Schedule of Property, Equipment and Leasehold Improvements (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Computer & related equipment	$ 200,414	$ 200,592
Furniture & fixtures	12,033	10,591
Leasehold improvements	53,429	51,128
Work-in-process	10,506	3,406
Subtotal	276,382	265,717
Accumulated depreciation and amortization	(185,505)	(171,280)
Property, equipment and leasehold improvements, net	$ 90,877	$ 94,437
Computer & Related Equipment [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	2 years
Computer & Related Equipment [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	5 years
Furniture & Fixtures [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	7 years
Leasehold improvements [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	1 year
Leasehold improvements [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Estimated Useful Lives	21 years

Property, Equipment and Leasehold Improvements - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property Plant And Equipment [Abstract]
Depreciation and amortization of property, equipment and leasehold improvements	$ 8,311	$ 7,453	$ 7,377	$ 8,205	$ 8,118	$ 9,325	$ 9,159	$ 8,838	$ 31,346	$ 35,440	$ 34,320

Goodwill and Intangible Assets - Schedule of Change to Company's Goodwill (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Goodwill [Line Items]
Goodwill, Beginning balance	$ 1,560,621	$ 1,555,850
Changes to goodwill	(11,635)
Foreign exchange translation adjustment	(3,225)	4,771
Goodwill, Ending balance	1,545,761	1,560,621
Index [Member]
Goodwill [Line Items]
Goodwill, Beginning balance	1,205,400	1,202,448
Foreign exchange translation adjustment	(1,996)	2,952
Goodwill, Ending balance	1,203,404	1,205,400
Analytics [Member]
Goodwill [Line Items]
Goodwill, Beginning balance	302,611	302,611
Changes to goodwill	(11,635)
Goodwill, Ending balance	290,976	302,611
All Other [Member]
Goodwill [Line Items]
Goodwill, Beginning balance	52,610	50,791
Foreign exchange translation adjustment	(1,229)	1,819
Goodwill, Ending balance	$ 51,381	$ 52,610

Goodwill and Intangible Assets - Schedule of Goodwill by Reportable Segment (Parenthetical) (Detail) - Analytics [Member] $ in Millions	Dec. 31, 2018 USD ($)
Financial Engineering Associates Inc [Member]
Goodwill [Line Items]
Impact of divestiture on goodwill	$ 2.9
Investor Force [Member]
Goodwill [Line Items]
Impact of divestiture on goodwill	$ 8.7

Goodwill and Intangible Assets - Additional Information (Detail) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Line Items]
Impairment of goodwill									$ 0	$ 0	$ 0
Amortization of intangible assets	$ 11,633,000	$ 11,681,000	$ 19,537,000	$ 11,338,000	$ 11,560,000	$ 10,614,000	$ 11,122,000	$ 11,251,000	54,189,000	44,547,000	47,033,000
Remaining unamortized value written off									7,900,000
Acquired Intangible Assets [Member]
Goodwill [Line Items]
Amortization of intangible assets									44,000,000	39,200,000	44,600,000
Capitalized Software [Member]
Goodwill [Line Items]
Amortization of intangible assets									$ 10,200,000	$ 5,400,000	$ 2,400,000

Goodwill and Intangible Assets - Schedule of Gross Carrying and Accumulated Amortization Amounts Related to Company's Identifiable Intangible Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Acquired Finite Lived Intangible Assets [Line Items]
Gross carrying value excluding foreign exchange translation adjustment	$ 832,339	$ 838,615
Foreign exchange translation adjustment	(9,569)	(9,167)
Gross carrying value	822,770	829,448
Accumulated amortization excluding foreign exchange translation adjustment	(544,383)	(509,238)
Foreign exchange translation adjustment	2,416	1,626
Accumulated amortization	(541,967)	(507,612)
Net carrying value excluding foreign exchange translation adjustment	287,956	329,377
Foreign exchange translation adjustment	(7,153)	(7,541)
Net carrying value	280,803	321,836
Customer Relationships [Member]
Acquired Finite Lived Intangible Assets [Line Items]
Gross carrying value excluding foreign exchange translation adjustment	356,700	361,199
Accumulated amortization excluding foreign exchange translation adjustment	(209,867)	(189,100)
Net carrying value excluding foreign exchange translation adjustment	$ 146,833	172,099
Customer Relationships [Member] \| Minimum [Member]
Acquired Finite Lived Intangible Assets [Line Items]
Estimated Remaining Useful Lives	5 years
Customer Relationships [Member] \| Maximum [Member]
Acquired Finite Lived Intangible Assets [Line Items]
Estimated Remaining Useful Lives	21 years
Trademarks/Trade Names [Member]
Acquired Finite Lived Intangible Assets [Line Items]
Gross carrying value excluding foreign exchange translation adjustment	$ 208,320	223,382
Accumulated amortization excluding foreign exchange translation adjustment	(123,345)	(116,691)
Net carrying value excluding foreign exchange translation adjustment	$ 84,975	106,691
Trademarks/Trade Names [Member] \| Minimum [Member]
Acquired Finite Lived Intangible Assets [Line Items]
Estimated Remaining Useful Lives	5 years
Trademarks/Trade Names [Member] \| Maximum [Member]
Acquired Finite Lived Intangible Assets [Line Items]
Estimated Remaining Useful Lives	21 years 6 months
Technology/Software [Member]
Acquired Finite Lived Intangible Assets [Line Items]
Gross carrying value excluding foreign exchange translation adjustment	$ 238,692	225,407
Accumulated amortization excluding foreign exchange translation adjustment	(198,974)	(193,095)
Net carrying value excluding foreign exchange translation adjustment	$ 39,718	32,312
Technology/Software [Member] \| Minimum [Member]
Acquired Finite Lived Intangible Assets [Line Items]
Estimated Remaining Useful Lives	3 years
Technology/Software [Member] \| Maximum [Member]
Acquired Finite Lived Intangible Assets [Line Items]
Estimated Remaining Useful Lives	8 years 6 months
Proprietary Data [Member]
Acquired Finite Lived Intangible Assets [Line Items]
Estimated Remaining Useful Lives	13 years
Gross carrying value excluding foreign exchange translation adjustment	$ 28,627	28,627
Accumulated amortization excluding foreign exchange translation adjustment	(12,197)	(10,352)
Net carrying value excluding foreign exchange translation adjustment	$ 16,430	$ 18,275

Goodwill and Intangible Assets - Estimated Amortization Expense for Succeeding Years (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
2019	$ 47,886
2020	46,339
2021	42,286
2022	35,819
2023	32,778
Thereafter	75,695
Net carrying value	$ 280,803	$ 321,836

Employee Benefits - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Pension and post-retirement benefit expenses	$ 22.8	$ 22.5	$ 21.6
Defined contribution plan expenses	19.2	18.6	17.6
Net periodic benefit expense	3.6	3.9	4.0
Fair value of the defined benefit plan assets	21.7	20.6
Other Non-current Liabilities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, liability	21.3	22.0
Cost of Revenues [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and post-retirement benefit expenses	10.2	10.3	9.5
Selling and Marketing [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and post-retirement benefit expenses	6.9	6.5	6.7
Research and Development [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and post-retirement benefit expenses	3.8	3.8	4.0
General and Administrative [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and post-retirement benefit expenses	1.8	1.3	$ 1.3
Other expense (income) [Member] \| Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension and post-retirement benefit expenses	$ 0.1	$ 0.6

Shareholders' Equity (Deficit) - Additional Information 1 (Detail) - USD ($)	Dec. 31, 2018	May 01, 2018	Oct. 26, 2016
2016 Repurchase Program [Member]
Equity, Class of Treasury Stock [Line Items]
Repurchase program authorizing the purchase of shares			$ 750,000,000
Stock repurchase program, remaining authorized repurchase amount		$ 523,100,000
2018 Repurchase Program [Member]
Equity, Class of Treasury Stock [Line Items]
Repurchase program authorizing the purchase of shares		$ 1,000,000,000
Stock repurchase program, remaining authorized repurchase amount	$ 808,100,000

Shareholders' Equity (Deficit) - Schedule of Company's Common Stock Repurchases Pursuant to Open Market Repurchases (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Equity, Class of Treasury Stock [Line Items]
Dollar Value of Shares Repurchased	$ 949,888	$ 150,461	$ 774,565
Open Market Purchases of Common Stock [Member]
Equity, Class of Treasury Stock [Line Items]
Average Price Paid Per Share	$ 148.34	$ 87.96	$ 73.71
Total Number of Shares Repurchased	6,236	1,556	10,303
Dollar Value of Shares Repurchased	$ 924,989	$ 136,899	$ 759,427

Shareholders' Equity (Deficit) - Schedule of Cash Dividends Declared and Distributed Per Common Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement Of Stockholders Equity [Abstract]
Dividend declared per common share	$ 0.58	$ 0.58	$ 0.38	$ 0.38	$ 0.38	$ 0.38	$ 0.28	$ 0.28	$ 0.28	$ 0.28	$ 0.22	$ 0.22	$ 1.92	$ 1.32	$ 1.00
Cash dividends declared, Amount	$ 50,907	$ 52,264	$ 34,254	$ 34,848	$ 34,745	$ 34,768	$ 25,710	$ 25,769	$ 26,524	$ 26,936	$ 21,588	$ 22,046	$ 172,273	$ 120,992	$ 97,094
Cash dividends distributed, Amount	50,434	51,764	33,935	34,900	34,448	34,403	25,444	25,500	26,304	26,680	21,391	21,889	171,033	119,795	96,264
Cash dividends deferred, Amount	$ 473	$ 500	$ 319	$ (52)	$ 297	$ 365	$ 266	$ 269	$ 220	$ 256	$ 197	$ 157	$ 1,240	$ 1,197	$ 830

Shareholders' Equity (Deficit) - Summary of Activity Related to Shares of Common Stock Issued and Repurchased (Detail) - shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Common Stock Issued [Member]
Common Stock Outstanding [Line Items]
Beginning balance	129,543,856	128,996,344	128,200,189
Dividend payable/paid	734	684	892
Common stock issued and exercise of stock options	479,277	538,448	788,304
Shares issued to directors	6,059	8,380	6,959
Ending balance	130,029,926	129,543,856	128,996,344
Treasury Stock [Member]
Common Stock Outstanding [Line Items]
Beginning balance	(39,438,971)	(37,716,754)	(27,187,041)
Dividend payable/paid	(579)	(528)	(472)
Shares withheld for tax withholding and exercises	(174,991)	(157,667)	(219,921)
Shares repurchased under stock repurchase programs	(6,235,629)	(1,556,313)	(10,303,047)
Shares issued to directors	(5,618)	(7,709)	(6,273)
Ending balance	(45,855,788)	(39,438,971)	(37,716,754)
Common Stock Outstanding [Member]
Common Stock Outstanding [Line Items]
Beginning balance	90,104,885	91,279,590	101,013,148
Dividend payable/paid	155	156	420
Common stock issued and exercise of stock options	479,277	538,448	788,304
Shares withheld for tax withholding and exercises	(174,991)	(157,667)	(219,921)
Shares repurchased under stock repurchase programs	(6,235,629)	(1,556,313)	(10,303,047)
Shares issued to directors	441	671	686
Ending balance	84,174,138	90,104,885	91,279,590

Shareholders' Equity (Deficit) - Additional Information 2 (Detail) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Feb. 22, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares grants in period		0	0	0
Tax benefits for share-based compensation expense related to deferred stock and stock options		$ 8.8	$ 5.5	$ 7.4
Compensation cost related to unvested share-based awards not yet recognized		$ 24.6
Number of shares available for future grants		7,000,000
Total fair value of Share-Based Awards converted or vested to common stock		$ 63.6	30.3	39.4
Intrinsic value of the stock options exercised		$ 4.8	$ 10.9	$ 11.3
Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Compensation cost related to unvested share-based awards not yet recognized, period for recognition		1 year
Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Compensation cost related to unvested share-based awards not yet recognized, period for recognition		3 years
Subsequent Events [Member] \| 2018 Bonus Award [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares grants in period	396,090
Amount of the award granted to retirement-eligible employees	$ 0.2
Aggregate fair value	$ 50.4
Subsequent Events [Member] \| 2018 Bonus Award [Member] \| RSUs [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period of awards	3 years
Fraction of bonus award vested per year	33.00%
Subsequent Events [Member] \| 2018 Bonus Award [Member] \| MSUs [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Minimum performance period	3 years
Maximum Performance Period	5 years
Subsequent Events [Member] \| 2018 Bonus Award [Member] \| MSUs [Member] \| Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period of awards	3 years
Subsequent Events [Member] \| 2018 Bonus Award [Member] \| MSUs [Member] \| Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period of awards	5 years

Shareholders' Equity (Deficit) - Components of Share-Based Compensation Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Awards [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total share-based compensation expense	$ 40,563	$ 37,921	$ 32,525

Shareholders' Equity (Deficit) - Summary of Share-based Compensation Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense	$ 40,563	$ 37,921	$ 32,525
Cost of Revenues [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense	10,334	9,707	7,971
Selling and Marketing [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense	12,851	11,355	9,526
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense	4,175	3,477	2,970
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense	$ 13,203	$ 13,382	$ 12,058

Shareholders' Equity (Deficit) - Summary of Vested and Unvested Share-Based Awards Activity (Detail) shares in Thousands	12 Months Ended
	Dec. 31, 2018 $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Vested and unvested Share-based Awards at the beginning of period, Number of Shares \| shares	1,419
Granted, Number of Shares \| shares	332
Conversion to common stock, Number of Shares \| shares	(451)
Canceled, Number of Shares \| shares	(12)
Vested and unvested Share-based Awards at the end of period, Number of Shares \| shares	1,288
Vested and unvested Share-based Awards at the beginning of period, Weighted Average Grant Date Fair Value \| $ / shares	$ 68.50
Granted, Weighted Average Grant Date Fair Value \| $ / shares	117.64
Conversion to common stock, Weighted Average Grant Date Fair Value \| $ / shares	65.40
Canceled, Weighted Average Grant Date Fair Value \| $ / shares	87.17
Vested and unvested Share-based Awards at the end of period, Weighted Average Grant Date Fair Value \| $ / shares	$ 82.09

Shareholders' Equity (Deficit) - Summary of Vested and Unvested Share-Based Awards Activity (Parenthetical) (Detail) shares in Thousands	Dec. 31, 2018 $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Share-based Awards, vested or expected to vest \| shares	1,261
Share-based Awards , vested or expected to vest, weighted average price \| $ / shares	$ 81.51

Shareholders' Equity (Deficit) - Summary of Unvested Share-Based Awards Activity (Detail) shares in Thousands	12 Months Ended
	Dec. 31, 2018 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted Average Grant Date Fair Value, balance at the beginning of the period \| $ / shares	$ 69.96
Weighted Average Grant Date Fair Value, Granted \| $ / shares	124.66
Weighted Average Grant Date Fair Value, Vested \| $ / shares	68.41
Weighted Average Grant Date Fair Value, Canceled \| $ / shares	87.17
Weighted Average Grant Date Fair Value, balance at the end of the period \| $ / shares	84.14
Weighted Average Grant Date Fair Value, Expected to vest \| $ / shares	$ 83.51
Unvested Shares [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unvested Share-based Awards at the beginning of period \| shares	1,166
Number of Shares, Granted \| shares	280
Number of Shares, Vested \| shares	(332)
Number of Shares, Canceled \| shares	(12)
Unvested Share-based Awards at the end of period \| shares	1,102
Unvested Share-based Awards expected to vest \| shares	1,075

Shareholders' Equity (Deficit) - Summary of Stock Options Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Options, Options outstanding, Beginning balance	145,000
Number of Options, Granted or assumed	0	0	0
Number of Options, Conversion to common stock	(33,000)
Number of Options, Options outstanding and exercisable, Ending balance	112,000
Weighted Average Exercise Price, Options outstanding, Beginning balance	$ 26.47
Weighted Average Exercise Price, Conversion to common stock	18.14
Weighted Average Exercise Price, Options outstanding and exercisable, Ending balance	$ 28.96
Weighted Average Remaining Life (Years), Options outstanding		2 years 1 month 9 days
Weighted Average Remaining Life (Years), Options outstanding and exercisable	1 year 3 months 10 days
Aggregated Intrinsic Value, Options outstanding and exercisable	$ 13,239	$ 14,519

Shareholders' Equity (Deficit) - Summary of Stock Options Outstanding and Exercisable by Exercise Price Range (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Number Outstanding, Options Outstanding and Exercisable	112
Weighted Average Exercise Price, Options Outstanding and Exercisable	$ 28.96
Average Remaining Life (Years), Options Outstanding and Exercisable	1 year 3 months 10 days
Aggregate Intrinsic Value, Options Outstanding and Exercisable	$ 13,239	$ 14,519
First Exercise Price Range [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Range of Exercise Price, Minimum	$ 15.18
Range of Exercise Price, Maximum	$ 16.48
Number Outstanding, Options Outstanding and Exercisable	12
Weighted Average Exercise Price, Options Outstanding and Exercisable	$ 16.48
Average Remaining Life (Years), Options Outstanding and Exercisable	1 month 24 days
Aggregate Intrinsic Value, Options Outstanding and Exercisable	$ 1,521
Second Exercise Price Range [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Range of Exercise Price, Minimum	$ 20.45
Range of Exercise Price, Maximum	$ 24.11
Number Outstanding, Options Outstanding and Exercisable	14
Weighted Average Exercise Price, Options Outstanding and Exercisable	$ 20.45
Average Remaining Life (Years), Options Outstanding and Exercisable	7 months 24 days
Aggregate Intrinsic Value, Options Outstanding and Exercisable	$ 1,798
Third Exercise Price Range [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Range of Exercise Prices	$ 25.64
Number Outstanding, Options Outstanding and Exercisable	36
Weighted Average Exercise Price, Options Outstanding and Exercisable	$ 25.64
Average Remaining Life (Years), Options Outstanding and Exercisable	11 months 15 days
Aggregate Intrinsic Value, Options Outstanding and Exercisable	$ 4,409
Fourth Exercise Price Range [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Range of Exercise Prices	$ 36.70
Number Outstanding, Options Outstanding and Exercisable	50
Weighted Average Exercise Price, Options Outstanding and Exercisable	$ 36.70
Average Remaining Life (Years), Options Outstanding and Exercisable	1 year 11 months 12 days
Aggregate Intrinsic Value, Options Outstanding and Exercisable	$ 5,511

Reclassifications out of Accumulated Other Comprehensive Income (Loss) - Schedule of Reclassifications Out of Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Income Taxes	$ (35,157)	$ (23,014)	$ (39,494)	$ (24,346)	$ (62,358)	$ (35,650)	$ (36,245)	$ (28,674)	$ (122,011)	$ (162,927)	$ (125,083)
Net income	$ 152,132	$ 123,832	$ 116,829	$ 115,092	$ 64,602	$ 85,153	$ 81,266	$ 72,951	507,885	303,972	260,855
Amount Reclassified from Accumulated Other Comprehensive Income (Loss) [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Net income									(168)	(204)	(188)
Amount Reclassified from Accumulated Other Comprehensive Income (Loss) [Member] \| Defined Benefit Pension Plans Amount Recognized as a Component of Net Periodic Benefit Expense [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income (Loss) [Line Items]
Net periodic benefit expense for curtailments and settlements									(222)	(281)	(261)
Income Taxes									$ 54	$ 77	$ 73

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Income Taxes - Summary of Provision for Income Taxes (Benefits) by Taxing Jurisdiction (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Current, U.S. federal									$ 51,316	$ 133,250	$ 93,071
Current, U.S. state and local									31,680	16,312	16,363
Current, Non U.S.									39,795	32,267	32,616
Current provision for income taxes (benefits)									122,791	181,829	142,050
Deferred, U.S. federal									(1,406)	(12,502)	(13,010)
Deferred, U.S. state and local									5,566	(2,119)	(2,235)
Deferred, Non U.S.									(4,940)	(4,281)	(1,722)
Deferred provision for income taxes (benefits)									(780)	(18,902)	(16,967)
Provision for income taxes	$ 35,157	$ 23,014	$ 39,494	$ 24,346	$ 62,358	$ 35,650	$ 36,245	$ 28,674	$ 122,011	$ 162,927	$ 125,083

Income Taxes - Reconciliation of U.S. Federal Statutory Income Tax Rate to the Effective Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
U.S. federal statutory income tax rate	21.00%	35.00%	35.00%
U.S. state and local income taxes, net of U.S. federal income tax benefits	4.66%	1.84%	2.38%
Change in tax rates applicable to non-U.S. earnings	(2.20%)	(7.60%)	(3.73%)
Domestic tax credits and incentives	(0.30%)	(0.24%)	(0.26%)
Net tax charge related to Tax Reform	(1.78%)	7.40%
Valuation allowance	(1.41%)
Excess Stock Based Compensation	(1.14%)	(1.25%)
Other	0.54%	(0.25%)	(0.98%)
Effective income tax rate	19.37%	34.90%	32.41%

Income Taxes - Additional Information (Detail)		12 Months Ended
Income Taxes - Additional Information (Detail)	Dec. 22, 2017	Dec. 31, 2018 USD ($) Subsidiary	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Income Tax Examination [Line Items]
U.S. federal income tax rate reduction effective date		Jan. 01, 2018
Tax reform measurement period	1 year
Net charge (benefit) to provision for income taxes		$ (11,200,000)	$ 34,500,000
Estimated tax charge related to toll charge			47,500,000
Estimated tax charge (benefit) related to change in assertion		(5,700,000)	16,000,000
Estimated tax benefit related to revaluation of deferred tax assets		2,900,000	(29,000,000)
Estimated tax benefit related to foreign withholding taxes		2,600,000
Cumulative net charge of tax reform		$ 23,300,000
Number of subsidiaries sold \| Subsidiary		2
Earnings attributable to foreign subsidiaries		$ 289,500,000	450,700,000	$ 341,600,000
Estimated tax charge related to foreign withholding taxes			$ 16,000,000
Significant change in unrecognized tax benefits, reasonably possible		It is reasonably possible that significant changes in the balance of unrecognized tax benefits may occur within the next 12 months.
Significant change in unrecognized tax benefits, not possible		At this time, however, it is not possible to reasonably estimate the expected change to the total amount of unrecognized tax benefits and the impact on the effective tax rate over the next 12 months.
Total amount of unrecognized tax benefits		$ 13,800,000
Unrecognized tax benefits, interest on income tax expense(benefit)		(200,000)
Penalties recognized during the year		0
Amount of accrued interest		$ 900,000
Minimum [Member]
Income Tax Examination [Line Items]
Tax years under examination		2006
Maximum [Member]
Income Tax Examination [Line Items]
Tax years under examination		2017
Capital Loss Carryover [Member]
Income Tax Examination [Line Items]
Capital loss carryover value		$ 42,400,000
Domestic Tax Authority [Member]
Income Tax Examination [Line Items]
Net operating loss carryforwards		$ 16,000,000
Expiration period		2024
Domestic Tax Authority [Member] \| Internal Revenue Service (IRS) [Member] \| Minimum [Member] \| Morgan Stanley [Member]
Income Tax Examination [Line Items]
Tax years under examination		2006
Domestic Tax Authority [Member] \| Internal Revenue Service (IRS) [Member] \| Maximum [Member] \| Morgan Stanley [Member]
Income Tax Examination [Line Items]
Tax years under examination		2008
Foreign Tax Authority [Member]
Income Tax Examination [Line Items]
Net operating loss carryforwards		$ 600,000
Operating loss carryforwards, valuation allowance		$ 600,000
State and Local Jurisdiction [Member] \| New York State Division of Taxation and Finance [Member] \| Minimum [Member] \| Morgan Stanley [Member]
Income Tax Examination [Line Items]
Tax years under examination		2007
State and Local Jurisdiction [Member] \| New York State Division of Taxation and Finance [Member] \| Maximum [Member] \| Morgan Stanley [Member]
Income Tax Examination [Line Items]
Tax years under examination		2008

Income Taxes - Significant Components of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Employee compensation and benefit plans	$ 19,698	$ 19,646
Deferred rent	5,392	5,308
Pension	2,466	1,520
Unearned revenue		853
Loss carryforwards - non-current	2,941	18,105
Other		1,435
Subtotal	30,497	46,867
Less: valuation allowance	(632)	(11,575)
Total deferred tax assets	29,865	35,292
Deferred tax liabilities:
Intangible assets	(65,538)	(73,634)
Unearned revenue	(1,170)
Unremitted foreign earnings	(12,872)	(16,108)
Property, equipment and leasehold improvements, net	(16,369)	(11,564)
Other	(1,021)
Total deferred tax liabilities	(96,970)	(101,306)
Net deferred tax liabilities	$ (67,105)	$ (66,014)

Income Taxes - Summary of Deferred Tax Asset Valuation Allowance (Detail) - Valuation Allowance of Deferred Tax Assets - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Valuation And Qualifying Accounts Disclosure [Line Items]
Beginning balance	$ 11,575	$ 17,807	$ 21,052
Additions charged to cost and expenses		324	1,862
Deductions	(10,943)	(6,556)	(5,107)
Ending balance	$ 632	$ 11,575	$ 17,807

Income Taxes - Summary of Components of Income Before Provision for Income Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Domestic									$ 399,000	$ 283,779	$ 263,536
Foreign									230,896	183,120	122,402
Income before provision for income taxes	$ 187,289	$ 146,846	$ 156,323	$ 139,438	$ 126,960	$ 120,803	$ 117,511	$ 101,625	$ 629,896	$ 466,899	$ 385,938

Income Taxes - Reconciliation of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Beginning balance	$ 10,022	$ 7,936	$ 8,692
Increases based on tax positions related to the current period	3,928	3,389	575
Increases based on tax positions related to prior periods	1,892	519	135
Decreases based on tax positions related to prior periods	(297)	(6)	(3)
Decreases related to settlements with taxing authorities		(1,152)	(1,463)
Decreases related to a lapse of applicable statute of limitations	(1,454)	(664)
Ending balance	$ 14,091	$ 10,022	$ 7,936

Divestitures - Additional Information (Detail) - USD ($) $ in Thousands			12 Months Ended
	Oct. 12, 2018	Apr. 09, 2018	Dec. 31, 2018	Dec. 31, 2016
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Proceeds from divestiture			$ 83,825	$ 657
Gain on divestiture			$ 61,402	$ 449
Financial Engineering Associates Inc [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Proceeds from divestiture		$ 21,000
Goodwill		2,900
Amortized identifiable intangible assets		2,700
Other net assets		6,100
Transaction costs		1,400
Financial Engineering Associates Inc [Member] \| Other Expense (Income) [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Gain on divestiture		$ 10,600
Investor Force [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Proceeds from divestiture	$ 62,000
Goodwill	8,700
Amortized identifiable intangible assets	4,000
Other net assets	700
Transaction costs	2,800
Additional working capital adjustment	800
Investor Force [Member] \| Other Expense (Income) [Member]
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]
Gain on divestiture	$ 46,600

Segment Information - Additional Information (Detail)	12 Months Ended
Segment Information - Additional Information (Detail)	Dec. 31, 2018 Segment
Segment Reporting [Abstract]
Number of operating segments	4

Segment Information - Operating Revenues by Reportable Segment (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting, Revenue Reconciling Item [Line Items]
Operating revenues	$ 361,688	$ 357,934	$ 363,046	$ 351,316	$ 334,779	$ 322,097	$ 316,089	$ 301,207	$ 1,433,984	$ 1,274,172	$ 1,150,669
Index [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Operating revenues									835,475	718,959	613,551
Analytics [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Operating revenues									479,939	458,269	448,353
All Other [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Operating revenues									$ 118,570	$ 96,944	$ 88,765

Segment Information - Segment Profitability and Reconciliation to Net Income (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Adjusted EBITDA									$ 772,433	$ 659,757	$ 569,457
Amortization of intangible assets	$ 11,633	$ 11,681	$ 19,537	$ 11,338	$ 11,560	$ 10,614	$ 11,122	$ 11,251	54,189	44,547	47,033
Depreciation and amortization of property, equipment and leasehold improvements	8,311	7,453	7,377	8,205	8,118	9,325	9,159	8,838	31,346	35,440	34,320
Operating income	169,818	176,403	173,511	167,166	154,139	148,799	146,100	130,732	686,898	579,770	488,104
Other expense (income), net	(17,471)	29,557	17,188	27,728	27,179	27,996	28,589	29,107	57,002	112,871	102,166
Provision for income taxes	35,157	23,014	39,494	24,346	62,358	35,650	36,245	28,674	122,011	162,927	125,083
Net income	$ 152,132	$ 123,832	$ 116,829	$ 115,092	$ 64,602	$ 85,153	$ 81,266	$ 72,951	507,885	303,972	260,855
Index [Member]
Segment Reporting Information [Line Items]
Adjusted EBITDA									607,853	522,241	431,478
Analytics [Member]
Segment Reporting Information [Line Items]
Adjusted EBITDA									143,645	125,624	128,507
All Other [Member]
Segment Reporting Information [Line Items]
Adjusted EBITDA									$ 20,935	$ 11,892	$ 9,472

Segment Information - Revenue by Geographic Area (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues from External Customers and Long-Lived Assets [Line Items]
Operating revenues	$ 361,688	$ 357,934	$ 363,046	$ 351,316	$ 334,779	$ 322,097	$ 316,089	$ 301,207	$ 1,433,984	$ 1,274,172	$ 1,150,669
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Operating revenues									662,345	622,132	556,777
Other [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Operating revenues									58,065	48,139	45,185
Total Americas [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Operating revenues									720,410	670,271	601,962
United Kingdom [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Operating revenues									214,204	193,831	175,749
Other [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Operating revenues									293,252	250,267	229,010
Europe, the Middle East and Africa ("EMEA") [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Operating revenues									507,456	444,098	404,759
Japan [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Operating revenues									67,100	54,351	52,161
Other [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Operating revenues									139,018	105,452	91,787
Total Asia & Australia [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Operating revenues									$ 206,118	$ 159,803	$ 143,948

Segment Information - Long-Lived Assets by Geographic Area (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 1,917,441	$ 1,976,894
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	1,803,321	1,847,605
Other [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	6,560	1,685
Total Americas [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	1,809,881	1,849,290
United Kingdom [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	80,039	94,782
Other [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	19,369	22,394
Total EMEA [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	99,408	117,176
Japan [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	411	432
Other [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	7,741	9,996
Total Asia & Australia [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 8,152	$ 10,428

Quarterly Results of Operations - Summary of Quarterly Results of Operations (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Operating revenues	$ 361,688	$ 357,934	$ 363,046	$ 351,316	$ 334,779	$ 322,097	$ 316,089	$ 301,207	$ 1,433,984	$ 1,274,172	$ 1,150,669
Cost of revenues	73,757	70,906	71,368	71,304	69,247	68,433	68,538	67,463	287,335	273,681	252,107
Selling and marketing	52,949	46,149	47,416	46,409	47,726	44,873	41,550	42,972	192,923	177,121	166,666
Research and development	20,312	20,591	19,801	20,707	20,709	17,974	18,196	18,970	81,411	75,849	75,204
General and administrative	24,908	24,751	24,036	26,187	23,280	22,079	21,424	20,981	99,882	87,764	87,235
Amortization of intangible assets	11,633	11,681	19,537	11,338	11,560	10,614	11,122	11,251	54,189	44,547	47,033
Depreciation and amortization of property, equipment and leasehold improvements	8,311	7,453	7,377	8,205	8,118	9,325	9,159	8,838	31,346	35,440	34,320
Total operating expenses	191,870	181,531	189,535	184,150	180,640	173,298	169,989	170,475	747,086	694,402	662,565
Operating income	169,818	176,403	173,511	167,166	154,139	148,799	146,100	130,732	686,898	579,770	488,104
Interest income	(6,096)	(6,522)	(4,281)	(2,770)	(2,237)	(1,835)	(1,310)	(932)	(19,669)	(6,314)	(2,906)
Interest expense	35,891	35,902	31,761	29,560	29,027	29,020	29,027	29,024	133,114	116,098	101,651
Other expense (income)	(47,266)	177	(10,292)	938	389	811	872	1,015	(56,443)	3,087	3,421
Other expense (income), net	(17,471)	29,557	17,188	27,728	27,179	27,996	28,589	29,107	57,002	112,871	102,166
Income before provision for income taxes	187,289	146,846	156,323	139,438	126,960	120,803	117,511	101,625	629,896	466,899	385,938
Provision for income taxes	35,157	23,014	39,494	24,346	62,358	35,650	36,245	28,674	122,011	162,927	125,083
Net income	$ 152,132	$ 123,832	$ 116,829	$ 115,092	$ 64,602	$ 85,153	$ 81,266	$ 72,951	$ 507,885	$ 303,972	$ 260,855
Earnings per basic common share	$ 1.75	$ 1.39	$ 1.31	$ 1.28	$ 0.72	$ 0.94	$ 0.90	$ 0.80	$ 5.83	$ 3.36	$ 2.72
Earnings per diluted common share	$ 1.70	$ 1.36	$ 1.28	$ 1.24	$ 0.70	$ 0.93	$ 0.89	$ 0.80	$ 5.66	$ 3.31	$ 2.70
Weighted average shares outstanding used in computing per share data
Basic	86,968	88,796	89,112	90,075	90,130	90,112	90,404	90,708	87,179	90,336	95,986
Diluted	89,495	91,372	91,586	92,587	92,467	91,868	91,708	91,624	89,701	91,914	96,540

Subsequent Events - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions		2 Months Ended	3 Months Ended												12 Months Ended
	Jan. 30, 2019	Feb. 15, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Subsequent Event [Line Items]
Quarterly dividend declared			$ 0.58	$ 0.58	$ 0.38	$ 0.38	$ 0.38	$ 0.38	$ 0.28	$ 0.28	$ 0.28	$ 0.28	$ 0.22	$ 0.22	$ 1.92	$ 1.32	$ 1.00
Value of share repurchased															$ 949,888	$ 150,461	$ 774,565
Subsequent Events [Member]
Subsequent Event [Line Items]
Quarterly dividend declared	$ 0.58
Quarterly dividend declared date	Jan. 30, 2019
Quarterly dividend payable date	Mar. 15, 2019
Quarterly dividend record date	Feb. 22, 2019
Total number of shares repurchased		0.7
Average price paid per share		$ 147.97
Value of share repurchased		$ 102,100