MarketAxess (MKTX) 10-Q 25 Oct 19 2019 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2019	Oct. 21, 2019
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Trading Symbol	MKTX
Entity Registrant Name	MARKETAXESS HOLDINGS INC
Entity Central Index Key	0001278021
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		37,777,078
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false
Title of 12(b) Security	Common Stock, $0.003 par value
Security Exchange Name	NASDAQ
Entity File Number	001-34091
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	52-2230784
Entity Address, Address Line One	55 Hudson Yards, 15th Floor
Entity Address, City or Town	New York
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10001
Document Quarterly Report	true
Document Transition Report	false
City Area Code	212
Local Phone Number	813-6000

Consolidated Statements of Fina

Consolidated Statements of Financial Condition - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
ASSETS
Cash and cash equivalents	$ 320,527	$ 246,322
Investments, at fair value	235,625	240,105
Accounts receivable, net of allowance of $146 and $80 as of September 30, 2019 and December 31, 2018, respectively	72,812	57,535
Goodwill and intangible assets, net of accumulated amortization	62,387	62,675
Furniture, equipment, leasehold improvements and capitalized software, net of accumulated depreciation and amortization	66,531	63,010
Operating lease right-of-use assets	75,390
Prepaid expenses and other assets	18,591	22,468
Deferred tax assets, net	3,163	3,424
Total assets	855,026	695,539
Liabilities
Accrued employee compensation	35,082	39,053
Income and other tax liabilities	13,274	16,432
Deferred revenue	3,731	2,810
Accounts payable, accrued expenses and other liabilities	16,285	29,366
Operating lease liabilities	92,031
Total liabilities	160,403	87,661
Commitments and Contingencies (Note 11)
Stockholders' equity
Common stock	122	122
Additional paid-in capital	343,543	341,860
Treasury stock - Common stock voting, at cost, 2,941,159 and 2,900,432 shares as of September 30, 2019 and December 31, 2018, respectively	(196,402)	(184,962)
Retained earnings	560,164	463,252
Accumulated other comprehensive loss	(12,804)	(12,394)
Total stockholders' equity	694,623	607,878
Total liabilities and stockholders' equity	855,026	695,539
Undefined Preferred Stock [Member]
Stockholders' equity
Preferred stock
Series A Preferred Stock [Member]
Stockholders' equity
Preferred stock

Consolidated Statements of Fi_2

Consolidated Statements of Financial Condition (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Allowance for accounts receivable	$ 146	$ 80
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	4,855,000	4,855,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.003	$ 0.003
Common stock, shares authorized	110,000,000	110,000,000
Common stock, shares issued	40,721,937	40,540,349
Common stock, shares outstanding	37,780,778	37,639,917
Treasury stock, shares	2,941,159	2,900,432
Series A Preferred Stock [Member]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	110,000	110,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common Stock Non-Voting [Member]
Common stock, par value	$ 0.003	$ 0.003
Common stock, shares authorized	10,000,000	10,000,000
Common stock, shares issued	0	0
Common stock, shares outstanding	0	0

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenues
Revenues	$ 131,597	$ 101,443	$ 381,578	$ 323,121
Expenses
Employee compensation and benefits	32,681	26,282	97,962	81,315
Depreciation and amortization	6,700	6,173	19,127	17,232
Technology and communications	7,381	5,879	19,637	17,451
Professional and consulting fees	7,018	5,685	19,145	16,168
Occupancy	2,802	3,528	8,549	10,332
Marketing and advertising	2,506	2,980	8,472	8,580
Clearing costs	2,782	1,760	7,969	5,497
General and administrative	3,762	2,744	10,686	7,927
Total expenses	65,632	55,031	191,547	164,502
Operating income	65,965	46,412	190,031	158,619
Other income (expense)
Investment income	2,211	1,635	6,296	4,186
Other, net	(838)	(250)	(860)	(785)
Total other income	1,373	1,385	5,436	3,401
Income before income taxes	67,338	47,797	195,467	162,020
Provision for income taxes	13,336	9,203	40,838	34,999
Net income	$ 54,002	$ 38,594	$ 154,629	$ 127,021
Net income per common share
Basic	$ 1.46	$ 1.04	$ 4.17	$ 3.44
Diluted	1.42	1.02	4.08	3.36
Cash dividends declared per common share	$ 0.51	$ 0.42	$ 1.53	$ 1.26
Weighted average shares outstanding
Basic	37,066	36,951	37,053	36,952
Diluted	37,995	37,828	37,913	37,859
Commissions [Member]
Revenues
Revenues	$ 119,869	$ 90,513	$ 346,753	$ 289,398
Information Services [Member]
Revenues
Revenues	7,693	7,174	22,215	21,170
Post-trade Services [Member]
Revenues
Revenues	3,784	3,475	11,840	11,671
Other [Member]
Revenues
Revenues	$ 251	$ 281	$ 770	$ 882

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 54,002	$ 38,594	$ 154,629	$ 127,021
Net cumulative translation adjustment and foreign currency exchange hedge, net of tax of $1,012, $240, $1,281 and $746, respectively	(1,416)	(582)	(1,398)	(1,602)
Net unrealized gain (loss) on securities available-for-sale, net of tax of $22, $23, $309 and $(66), respectively	70	72	988	(205)
Comprehensive income	$ 52,656	$ 38,084	$ 154,219	$ 125,214

Consolidated Statements of Co_2

Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement Of Income And Comprehensive Income [Abstract]
Foreign currency exchange hedge, tax expense (benefit)	$ 1,012	$ 240	$ 1,281	$ 746
Securities available-for-sale, tax expense (benefit)	$ 22	$ 23	$ 309	$ (66)

Consolidated Statements of Chan

Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock Voting [Member]	Additional Paid-In Capital [Member]	Treasury Stock - Common Stock Voting [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]
Beginning Balance at Dec. 31, 2017	$ 514,768	$ 121	$ 331,081	$ (159,791)	$ 353,583	$ (10,226)
Net income	47,940				47,940
Cumulative translation adjustment and foreign currency exchange hedge, net of tax	268					268
Unrealized net gain (loss) on securities available-for-sale, net of tax	(334)					(334)
Stock-based compensation	3,951		3,951
Exercise of stock options	258		258
Withholding tax payments on restricted stock vesting and stock option exercises	(7,621)		(7,621)
Repurchases of common stock	(6,268)			(6,268)
Cash dividend on common stock	(15,798)				(15,798)
Ending Balance at Mar. 31, 2018	537,164	121	327,669	(166,059)	385,725	(10,292)
Beginning Balance at Dec. 31, 2017	514,768	121	331,081	(159,791)	353,583	(10,226)
Net income	127,021
Cumulative translation adjustment and foreign currency exchange hedge, net of tax	(1,602)
Ending Balance at Sep. 30, 2018	578,618	121	336,079	(178,776)	433,227	(12,033)
Beginning Balance at Mar. 31, 2018	537,164	121	327,669	(166,059)	385,725	(10,292)
Net income	40,487				40,487
Cumulative translation adjustment and foreign currency exchange hedge, net of tax	(1,288)					(1,288)
Unrealized net gain (loss) on securities available-for-sale, net of tax	57					57
Stock-based compensation	3,650		3,650
Exercise of stock options	113		113
Withholding tax payments on restricted stock vesting and stock option exercises	(376)		(376)
Repurchases of common stock	(6,636)			(6,636)
Cash dividend on common stock	(15,793)				(15,793)
Ending Balance at Jun. 30, 2018	557,378	121	331,056	(172,695)	410,419	(11,523)
Net income	38,594				38,594
Cumulative translation adjustment and foreign currency exchange hedge, net of tax	(582)					(582)
Unrealized net gain (loss) on securities available-for-sale, net of tax	72					72
Stock-based compensation	3,950		3,950
Exercise of stock options	1,016		1,016
Withholding tax payments on restricted stock vesting and stock option exercises	57		57
Repurchases of common stock	(6,081)			(6,081)
Cash dividend on common stock	(15,786)				(15,786)
Ending Balance at Sep. 30, 2018	578,618	121	336,079	(178,776)	433,227	(12,033)
Beginning Balance at Dec. 31, 2018	607,878	122	341,860	(184,962)	463,252	(12,394)
Net income	52,522				52,522
Cumulative translation adjustment and foreign currency exchange hedge, net of tax	1,118					1,118
Unrealized net gain (loss) on securities available-for-sale, net of tax	459					459
Stock-based compensation	5,196		5,196
Exercise of stock options	172		172
Withholding tax payments on restricted stock vesting and stock option exercises	(11,803)		(11,803)
Repurchases of common stock	(5,184)			(5,184)
Cash dividend on common stock	(19,212)				(19,212)
Ending Balance at Mar. 31, 2019	631,146	122	335,425	(190,146)	496,562	(10,817)
Beginning Balance at Dec. 31, 2018	607,878	122	341,860	(184,962)	463,252	(12,394)
Net income	154,629
Cumulative translation adjustment and foreign currency exchange hedge, net of tax	(1,398)
Ending Balance at Sep. 30, 2019	694,623	122	343,543	(196,402)	560,164	(12,804)
Beginning Balance at Mar. 31, 2019	631,146	122	335,425	(190,146)	496,562	(10,817)
Net income	48,105				48,105
Cumulative translation adjustment and foreign currency exchange hedge, net of tax	(1,100)					(1,100)
Unrealized net gain (loss) on securities available-for-sale, net of tax	459					459
Stock-based compensation	5,929		5,929
Exercise of stock options	350		350
Withholding tax payments on restricted stock vesting and stock option exercises	(258)		(258)
Repurchases of common stock	(3,486)			(3,486)
Cash dividend on common stock	(19,237)				(19,237)
Ending Balance at Jun. 30, 2019	661,908	122	341,446	(193,632)	525,430	(11,458)
Net income	54,002				54,002
Cumulative translation adjustment and foreign currency exchange hedge, net of tax	(1,416)					(1,416)
Unrealized net gain (loss) on securities available-for-sale, net of tax	70					70
Stock-based compensation	7,944		7,944
Exercise of stock options	363		363
Withholding tax payments on restricted stock vesting and stock option exercises	(6,210)		(6,210)
Repurchases of common stock	(2,770)			(2,770)
Cash dividend on common stock	(19,268)				(19,268)
Ending Balance at Sep. 30, 2019	$ 694,623	$ 122	$ 343,543	$ (196,402)	$ 560,164	$ (12,804)

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities
Net income	$ 154,629	$ 127,021
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	19,127	17,232
Amortization of operating lease right-of-use assets	4,304
Stock-based compensation expense	19,069	11,551
Deferred taxes	73	162
Other	886	2,005
Changes in operating assets and liabilities:
(Increase) in accounts receivable	(15,479)	(9,560)
Decrease in prepaid expenses and other assets	3,855	97
Decrease (Increase) in trading securities	(371)	6,671
(Decrease) in accrued employee compensation	(3,971)	(5,034)
(Decrease) in income and other tax liabilities	(3,279)	(755)
Increase in deferred revenue	921	1,125
(Decrease) increase in accounts payable, accrued expenses and other liabilities	(2,000)	4,614
Increase in operating lease liabilities	800
Net cash provided by operating activities	176,794	153,812
Cash flows from investing activities
Proceeds from maturities and sales, available-for-sale investments	156,809	256,301
Purchases, available-for-sale investments	(149,575)	(260,318)
Purchases of furniture, equipment and leasehold improvements	(8,683)	(23,821)
Capitalization of software development costs	(13,863)	(9,171)
Other	22	25
Net cash (used in) investing activities	(15,290)	(36,984)
Cash flows from financing activities
Cash dividend on common stock	(57,233)	(46,893)
Exercise of stock options	885	1,387
Withholding tax payments on restricted stock vesting and stock option exercises	(18,271)	(7,940)
Repurchases of common stock	(11,440)	(18,985)
Net cash (used in) financing activities	(86,059)	(72,431)
Effect of exchange rate changes on cash and cash equivalents	(1,261)	(1,326)
Cash and cash equivalents including restricted cash
Net increase for the period	74,184	43,071
Beginning of period	247,458	168,150
End of period	321,642	211,221
Non-cash activity
Operating lease right-of-use assets obtained in exchange for operating lease liabilities	422
Mutual Funds Held In Rabbi Trust [Member]
Changes in operating assets and liabilities:
Decrease (Increase) in trading securities	$ (1,770)	$ (1,317)

Organization and Principal Busi

Organization and Principal Business Activity	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Organization and Principal Business Activity	1. Organization and Principal Business Activity MarketAxess Holdings Inc. (the “Company” or “MarketAxess”) was incorporated in the State of Delaware on April 11, 2000.

Significant Accounting Policies

Significant Accounting Policies	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Significant Accounting Policies	2. Significant Accounting Policies Basis of Presentation The consolidated financial statements include the accounts of the Company and its subsidiaries. All intercompany transactions and balances have been eliminated. These consolidated financial statements are unaudited and should be read in conjunction with the audited consolidated financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2018. The consolidated financial information as of December 31, 2018 has been derived from audited financial statements not included herein. These unaudited consolidated financial statements are prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) and the rules and regulations of the U.S. Securities and Exchange Commission (“SEC”) with respect to Form 10-Q and reflect all adjustments that, in the opinion of management, are normal and recurring, and that are necessary for a fair statement of the results for the interim periods presented. In accordance with such rules and regulations, certain disclosures that are normally included in annual financial statements have been omitted. Interim period operating results may not be indicative of the operating results for a full year. Accounting Pronouncements, Recently Adopted In February 2016, the Financial Accounting Standards Board (“FASB”) issued ASU 2016-02, “Leases” (“ASU 2016-02”) requiring lessees to recognize lease assets and lease liabilities on the balance sheet for those leases previously classified as operating leases with lease terms greater than 12 months. The Company adopted ASU 2016-02 effective January 1, 2019 using a modified retrospective transition approach and will not restate comparative periods. In addition, the Company elected the package of practical expedients permitted under the transition guidance within the new standard which allowed it to carry forward the historical lease classification. In August 2018, the FASB issued ASU 2018-15, “Intangibles—Goodwill and Other—Internal-Use Software: Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract” (“ASU 2018-15”). The standard requires the capitalization of implementation costs incurred in a cloud computing arrangement to be aligned with the requirements for capitalizing costs incurred to develop or obtain internal-use software. The updated guidance is effective for annual and interim reporting periods beginning after December 15, 2019, with early adoption permitted. The Company adopted ASU 2018-15 effective July 1, 2019 on a prospective basis. The Company completed its analysis and the adoption of this guidance did not have a material impact on the Company’s Consolidated Financial Statements. Accounting Pronouncements, Not Yet Adopted as of September 30, 2019 In January 2017, the FASB issued ASU 2017-04, “Intangibles-Goodwill and Other” (“ASU 2017-04”). ASU 2017-04 simplifies the testing for goodwill impairment. The guidance will be effective for the Company beginning January 1, 2020 and early adoption is permitted and should be applied prospectively. The adoption of this guidance is not expected to have a material effect on the Company’s Consolidated Financial Statements. Cash and Cash Equivalents Cash and cash equivalents includes cash and money market instruments that are primarily maintained at one major global bank. Given this concentration, the Company is exposed to certain credit risk in relation to its deposits at this bank. The Company defines cash equivalents as short-term interest-bearing investments with maturities at the time of purchase of three months or less. Investments The Company determines the appropriate classification of securities at the time of purchase which are recorded in the Consolidated Statements of Financial Condition on the trade date. Securities are classified as available-for-sale or trading. The Company’s available-for-sale investments are comprised of investment grade corporate debt securities. Available-for-sale investments are carried at fair value with the unrealized gains or losses reported in accumulated other comprehensive loss in the Consolidated Statements of Financial Condition. Trading investments include investment grade corporate debt securities and U.S. Treasuries and are carried at fair value, with realized and unrealized gains or losses included in other income in the Consolidated Statements of Operations. The Company assesses whether an other-than-temporary impairment loss on the available-for-sale investments has occurred due to declines in fair value or other market conditions. The portion of an other-than-temporary impairment related to credit loss is recorded as a charge in the Consolidated Statements of Operations. The remainder is recognized in accumulated other comprehensive loss if the Company does not intend to sell the security and it is more likely than not that the Company will not be required to sell the security prior to recovery. No charges for other-than-temporary losses were recorded during the three month and nine month periods ended September 30, 2019 and 2018, respectively. Fair Value Financial Instruments Fair value is defined as “the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date.” A three-tiered hierarchy for determining fair value has been established that prioritizes inputs to valuation techniques used in fair value calculations. The three levels of inputs are defined as Level 1 (unadjusted quoted prices for identical assets or liabilities in active markets), Level 2 (inputs that are observable in the marketplace other than those inputs classified in Level 1) and Level 3 (inputs that are unobservable in the marketplace). The Company’s financial assets and liabilities measured at fair value on a recurring basis consist of its money market funds, securities available-for-sale, trading securities and foreign currency forward contracts. All other financial instruments are short-term in nature and the carrying amount is reported on the Consolidated Statements of Financial Condition at approximate fair value. Allowance for Doubtful Accounts All accounts receivable have contractual maturities of less than one year and are derived from trading-related fees and commissions and revenues from products and services. The Company continually monitors collections and payments from its customers and maintains an allowance for doubtful accounts. The allowance for doubtful accounts is based upon the historical collection experience and specific collection issues that have been identified. Additions to the allowance for doubtful accounts are charged to bad debt expense, which is included in general and administrative expense in the Company’s Consolidated Statements of Operations. Depreciation and Amortization Fixed assets are carried at cost less accumulated depreciation. The Company uses the straight-line method of depreciation over three to seven years. The Company amortizes leasehold improvements on a straight-line basis over the lesser of the life of the improvement or the remaining term of the lease. Software Development Costs The Company capitalizes certain costs associated with the development of internal use software, including, among other items, employee compensation and related benefits and third party consulting costs at the point at which the conceptual formulation, design and testing of possible software project alternatives have been completed. Once the product is ready for its intended use, such costs are amortized on a straight-line basis over three years. The Company reviews the amounts capitalized for impairment whenever events or changes in circumstances indicate that the carrying amounts of the assets may not be recoverable. Cloud Computing Costs The Company capitalizes certain costs associated with cloud computing arrangements, including, among other items, employee compensation and related benefits and third party consulting costs that are part of the application development stage. These costs are setup as a pre-paid asset on the balance sheet and are amortized over the period of the hosting service contract. The Company reviews the amounts capitalized for impairment whenever events or changes in circumstances indicate that the carrying amounts of the assets may not be recoverable. Cash Provided as Collateral Cash is provided as collateral for broker-dealer clearing accounts. Cash provided as collateral is included in prepaid expenses and other assets in the Consolidated Statements of Financial Condition. Foreign Currency Translation and Forward Contracts Assets and liabilities denominated in foreign currencies are translated using exchange rates at the end of the period; revenues and expenses are translated at average monthly rates. Gains and losses on foreign currency translation are a component of accumulated other comprehensive loss in the Consolidated Statements of Financial Condition. Transaction gains and losses are recorded in other, net in the Consolidated Statements of Operations. The Company enters into foreign currency forward contracts to hedge its net investment in its U.K. subsidiaries. Gains and losses on these transactions are included in accumulated other comprehensive loss in the Consolidated Statements of Financial Condition. Revenue Recognition The Company’s classification of revenues in the Consolidated Statements of Operations represents revenues from contracts with customers disaggregated by type of revenue. The Company has four revenue streams as described below. Commission Revenue – The Company charges its broker-dealer clients variable transaction fees for trades executed on its platform and, under certain plans, distribution fees or monthly minimum fees to use the platform for a particular product area. Variable transaction fees are generally calculated as a percentage of the notional dollar volume of bonds traded on the platform and vary based on the type, size, yield and maturity of the bond traded. Under the Company’s disclosed trading transaction fee plans, bonds that are more actively traded or that have shorter maturities are generally charged lower commissions, while bonds that are less actively traded or that have longer maturities generally command higher commissions. Variable transaction fees, distribution fees and unused monthly fee commitments are invoiced and recorded on a monthly basis. For trades that the Company executes between and among institutional investor and broker-dealer clients on a matched principal basis by serving as counterparty to both the buyer and the seller, the Company earns its commission through the difference in price between the two trades. The commission is collected upon settlement of the trade, which typically occurs within one to two trading days after the trade date. The following table presents commission revenue by fee type for the three and nine months ended September 30, 2019 and 2018: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (In thousands) Commission revenue by fee type Variable transaction fees Disclosed trading $ 69,541 $ 49,727 $ 202,905 $ 172,443 Open Trading - matched principal trading 26,444 16,228 72,934 44,943 Total variable transaction fees 95,985 65,955 275,839 217,386 Distribution fees and unused minimum fees 23,884 24,558 70,914 72,012 Total commissions $ 119,869 $ 90,513 $ 346,753 $ 289,398 Information services – Information services includes data licensed to the Company’s broker-dealer clients, institutional investor clients and data-only subscribers; professional and consulting services; technology software licenses; and maintenance and support services. The nature and timing of each performance obligation may vary as these contracts are either subscription based services transferred over time or one-time services that are transferred at a point in time. Revenues for services transferred over time are recognized ratably over the contract period as the Company’s performance obligation is met whereas revenues for services transferred at a point in time are recognized in the period the services are provided. Customers are generally billed monthly, quarterly, or annually; revenues billed in advance are deferred and recognized ratably over the contract period. The following table presents information services revenue by timing of recognition for the three and nine months ended September 30, 2019 and 2018: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (In thousands) Information services revenue by timing of recognition Services transferred over time $ 7,203 $ 7,029 $ 21,472 $ 20,652 Services transferred at a point in time 490 145 743 518 Total information services revenues $ 7,693 $ 7,174 $ 22,215 $ 21,170 Post-trade services – Post-trade services revenue is generated from regulatory transaction reporting, trade publication and trade matching services. Customers are generally billed monthly in arrears and revenue is recognized in the period transactions are processed. Revenues billed in advance are deferred and recognized ratably over the contract period. The Company also generates one-time implementation fees for onboarding clients which are invoiced and recognized in the period the implementation is completed. The following table presents post-trade services revenue by timing of recognition for the three and nine months ended September 30, 2019 and 2018: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (In thousands) Post-trade services revenue by timing of recognition Services transferred over time $ 3,775 $ 3,463 $ 11,811 $ 11,370 Services transferred at a point in time 9 12 29 301 Total post-trade services revenues $ 3,784 $ 3,475 $ 11,840 $ 11,671 Other revenues – Other revenues primarily includes revenue from telecommunications line charges to broker-dealer clients. Contract liabilities consist of deferred revenues that the Company records when cash payments are received or due in advance of services to be performed. The revenue recognized from contract liabilities and the remaining balance is shown below: December 31, 2018 Payments received in advance of services to be performed Revenue recognized for services performed during the period Foreign Currency Translation September 30, 2019 (In thousands) Information services $ 1,959 $ 6,030 $ (5,437 ) $ — $ 2,552 Post-trade services 851 9,538 (9,180 ) (30 ) 1,179 Total deferred revenue $ 2,810 $ 15,568 $ (14,617 ) $ (30 ) $ 3,731 The majority of the Company’s contracts are short-term in nature with durations of less than one-year. For contracts extending beyond one year, the aggregate amount of the transaction price allocated to remaining performance obligations was $27.9 million as of September 30, 2019. The Company expects to recognize revenue associated with the remaining performance obligations over the next 29 months. Stock-Based Compensation The Company measures and recognizes compensation expense for all share-based payment awards based on their estimated fair values measured as of the grant date. These costs are recognized as an expense in the Consolidated Statements of Operations over the requisite service period, which is typically the vesting period, with an offsetting increase to additional paid-in capital. Forfeitures are recognized as they occur. Income Taxes Income taxes are accounted for using the asset and liability method. 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. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. A valuation allowance is recognized against deferred tax assets if it is more likely than not that such assets will not be realized in future years. The Company recognizes interest and penalties related to unrecognized tax benefits in general and administrative expenses in the Consolidated Statements of Operations. Effective upon the Company’s adoption of ASU 2016-09, all tax effects related to share-based payments are recorded through tax expense in the periods during which the awards are exercised or vest. Business Combinations, Goodwill and Intangible Assets Business combinations are accounted for under the purchase method of accounting. The total cost of an acquisition is allocated to the underlying net assets based on their respective estimated fair values. The excess of the purchase price over the estimated fair values of the net assets acquired is recorded as goodwill. Determining the fair value of certain assets acquired and liabilities assumed requires judgment and often involves the use of significant estimates and assumptions, including assumptions with respect to future cash flows, discount rates, growth rates and asset lives. The Company operates as a single reporting unit. Subsequent to an acquisition, goodwill no longer retains its identification with a particular acquisition, but instead becomes identifiable with the entire reporting unit. As a result, all of the fair value of the Company is available to support the value of goodwill. An impairment review of goodwill is performed on an annual basis, at year-end, or more frequently if circumstances change. Intangible assets with definite lives, including purchased technologies, customer relationships and other intangible assets, are amortized on a straight-line basis over their estimated useful lives, ranging from three to 15 years. Intangible assets are assessed for impairment when events or circumstances indicate the existence of a possible impairment. Earnings Per Share Basic earnings per share is computed by dividing the net income attributable to common stock by the weighted-average number of shares of common stock outstanding during the period. For purposes of computing diluted earnings per share, the weighted-average shares outstanding of common stock reflects the dilutive effect that could occur if convertible securities or other contracts to issue common stock were converted into or exercised for common stock. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.

Net Capital Requirements

Net Capital Requirements	9 Months Ended
	Sep. 30, 2019
Brokers And Dealers [Abstract]
Net Capital Requirements	3. Net Capital Requirements Certain U.S. subsidiaries of the Company are registered as a broker-dealer or swap execution facility (“SEF”) and therefore are subject to the applicable rules and regulations of the SEC and the Commodity Futures Trading Commission (“CFTC”). These rules contain minimum net capital requirements, as defined in the applicable regulations, and also may require that a significant part of the registrants’ assets be kept in relatively liquid form. Certain of the Company’s foreign subsidiaries are regulated by the Financial Conduct Authority in the U.K. or other foreign regulators and must maintain financial resources, as defined in the applicable regulations, in excess of the applicable financial resources requirement. As of September 30, 2019, each of the Company’s subsidiaries that are subject to these regulations had net capital or financial resources in excess of their minimum requirements. As of September 30, 2019, the Company’s subsidiaries maintained aggregate net capital and financial resources that was $182.9 million in excess of the required levels of $14.3 million. Each of the Company’s U.S. and foreign regulated subsidiaries are subject to local regulations which generally prohibit repayment of borrowings from the Company or affiliates, paying cash dividends, making loans to the Company or affiliates or otherwise entering into transactions that result in a significant reduction in regulatory net capital or financial resources without prior notification to or approval from such regulated entity’s principal regulator.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurements	4. Fair Value Measurements The following table summarizes the valuation of the Company’s assets and liabilities measured at fair value as categorized based on the hierarchy described in Note 2. Level 1 Level 2 Level 3 Total (In thousands) As of September 30, 2019 Money market funds $ 163,734 $ — $ — $ 163,734 Securities available-for-sale Corporate debt — 140,812 — 140,812 Trading securities Corporate debt — 33,697 — 33,697 U.S. Treasuries — 55,248 — 55,248 Mutual funds held in rabbi trust — 5,868 — 5,868 Foreign currency forward position — 231 — 231 Total $ 163,734 $ 235,856 $ — $ 399,590 As of December 31, 2018 Money market funds $ 112,529 $ — $ — $ 112,529 Securities available-for-sale Corporate debt — 146,966 — 146,966 Trading securities Corporate debt — 71,861 — 71,861 U.S. Treasuries — 17,178 — 17,178 Mutual funds held in rabbi trust — 4,100 — 4,100 Foreign currency forward position — (1,021 ) — (1,021 ) Total $ 112,529 $ 239,084 $ — $ 351,613 Securities classified within Level 2 were valued using a market approach utilizing prices and other relevant information generated by market transactions involving comparable assets. The foreign currency forward contracts are classified within Level 2 as the valuation inputs are based on quoted market prices. The mutual funds held in a rabbi trust represent investments associated with the Company’s deferred cash incentive plan. There were no financial assets classified within Level 3 during the nine months ended September 30 , 201 9 and 201 8 . The Company enters into foreign currency forward contracts to hedge the net investment in the Company’s U.K. subsidiaries. The Company designates each foreign currency forward contract as a hedge and assesses the risk management objective and strategy, including identification of the hedging instrument, the hedged item and the risk exposure and how effectiveness is to be assessed prospectively and retrospectively. These hedges are for a one-month period and are used to limit exposure to foreign currency exchange rate fluctuations. The fair value of the asset is included in prepaid expenses and other assets and the fair value of the liability is included in accounts payable, accrued expenses and other liabilities in the Consolidated Statements of Financial Condition. Gains or losses on foreign currency forward contracts designated as hedges are included in accumulated other comprehensive loss in the Consolidated Statements of Financial Condition. A summary of the Company’s foreign currency forward position is as follows: As of September 30, 2019 December 31, 2018 (In thousands) Notional value $ 134,907 $ 106,306 Fair value of notional 134,676 107,327 Fair value of the asset (liability) $ 231 $ (1,021 ) The following is a summary of the Company’s investments: Amortized cost Gross unrealized gains Gross unrealized losses Estimated fair value (In thousands) As of September 30, 2019 Securities available-for-sale Corporate debt $ 140,104 $ 732 $ (24 ) $ 140,812 Trading securities Corporate debt 33,676 30 (9 ) 33,697 U.S. Treasuries 54,661 587 — 55,248 Mutual funds held in rabbi trust 5,173 695 — 5,868 Total trading securities 93,510 1,312 (9 ) 94,813 Total investments $ 233,614 $ 2,044 $ (33 ) $ 235,625 As of December 31, 2018 Securities available-for-sale Corporate debt $ 147,556 $ 27 $ (617 ) $ 146,966 Trading securities Corporate debt 72,274 8 (421 ) 71,861 U.S. Treasuries 16,953 225 — 17,178 Mutual funds held in rabbi trust 4,347 — (247 ) 4,100 Total trading securities 93,574 233 (668 ) 93,139 Total investments $ 241,130 $ 260 $ (1,285 ) $ 240,105 The following table summarizes the fair value of the investments based upon the contractual maturities: As of September 30, 2019 December 31, 2018 (In thousands) Less than one year $ 116,365 $ 134,255 Due in 1 - 5 years 119,260 105,850 Total $ 235,625 $ 240,105 Proceeds from the sales and maturities of investments during the nine months ended September 30, 2019 and 2018 were $238.5 million and $308.3 million, respectively. The following table provides fair values and unrealized losses on investments and by the aging of the securities’ continuous unrealized loss position as of September 30, 2019 and December 31, 2018: Less than Twelve Months Twelve Months or More Total Estimated fair value Gross unrealized losses Estimated fair value Gross unrealized losses Estimated fair value Gross unrealized losses (In thousands) As of September 30, 2019 Corporate debt $ 21,666 $ (19 ) $ 16,916 $ (14 ) $ 38,582 $ (33 ) As of December 31, 2018 Corporate debt $ 80,282 $ (256 ) $ 87,028 $ (782 ) $ 167,310 $ (1,038 )

Goodwill and Intangible Assets

Goodwill and Intangible Assets	9 Months Ended
	Sep. 30, 2019
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	5. Goodwill and Intangible Assets Goodwill and intangible assets with indefinite lives was $59.7 million as of both September 30, 2019 and December 31, 2018. Intangible assets that are subject to amortization, including the related accumulated amortization, are comprised of the following: September 30, 2019 December 31, 2018 Cost Accumulated amortization Net carrying amount Cost Accumulated amortization Net carrying amount (In thousands) Technology $ 5,770 $ (5,770 ) $ — $ 5,770 $ (5,770 ) $ — Customer relationships 5,627 (2,952 ) 2,675 5,634 (2,672 ) 2,962 Non-competition agreements 380 (380 ) — 380 (380 ) — Tradenames 370 (370 ) — 370 (370 ) — Total $ 12,147 $ (9,472 ) $ 2,675 $ 12,154 $ (9,192 ) $ 2,962 Amortization expense associated with identifiable intangible assets was $0.3 million for each of the nine months ended September 30, 2019 and 2018, respectively. Estimated total amortization expense is $0.4 million for each year from 2019 through 2022 and $0.3 million for 2023.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Income Taxes	6. Income Taxes The provision for income taxes consists of the following: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Current: (In thousands) Federal $ 9,628 $ 6,358 $ 26,100 $ 23,119 State and local 1,865 1,619 5,215 5,616 Foreign 3,385 2,502 9,429 6,036 Total current provision 14,878 10,479 40,744 34,771 Deferred: Federal (1,231 ) (663 ) 195 (321 ) State and local (214 ) (136 ) 4 (107 ) Foreign (97 ) (477 ) (105 ) 656 Total deferred provision (1,542 ) (1,276 ) 94 228 Provision for income taxes $ 13,336 $ 9,203 $ 40,838 $ 34,999 T he Company recognized excess tax benefits on share-based payments of $ million and $ million through the provision for income taxes, for the three months ended September 30, 2019 and 2018, respectively, and $7.0 million and $3.7 million for the nine months ended September 30, 2019 and 2018, respectively. The Company or one of its subsidiaries files U.S. federal, state and foreign income tax returns. Income tax returns for U.S. Federal (through 2013), New York City (through 2003) and state (through 2009) and Connecticut state (through 2003) have been audited. An examination of the Company’s New York State income tax returns for 2010 through 2017 is currently underway. The Company cannot estimate when the examination will conclude or the impact such examination will have on the Company’s Consolidated Financial Statements, if any. All previously undistributed foreign earnings have now been subject to U.S. tax. Notwithstanding the U.S. taxation of these amounts, the Company considers its undistributed foreign earnings to be indefinitely reinvested outside of the U.S. and does not expect to incur any significant additional taxes related to such amounts.

Stock-Based Compensation Plans

Stock-Based Compensation Plans	9 Months Ended
	Sep. 30, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation Plans	7. Stock-Based Compensation Plans Total stock-based compensation expense was as follows: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (In thousands) Employees $ 7,706 $ 3,654 $ 18,267 $ 10,739 Non-employee directors 238 296 802 812 Total stock-based compensation $ 7,944 $ 3,950 $ 19,069 $ 11,551 The Company records stock-based compensation expense for employees in employee compensation and benefits and for non-employee directors in general and administrative expenses in the Consolidated Statements of Operations. During the nine months ended September 30, 2019, the Company granted to employees a total of 97,244 shares of restricted stock or restricted stock units, 82,474 options to purchase shares of common stock and performance-based shares with an expected pay-out at target of 16,716 shares of common stock. The fair value of the restricted stock and performance-based share awards was based on a weighted-average fair value per share at the grant date of $242.74 and $224.13, respectively. Based on the Black-Scholes option pricing model, the weighted-average fair value for each option granted was $38.83 per share. In addition to the grants above, 76,868 stock options and 18,914 performance shares were granted to the Company’s President and Chief Operating Officer in January 2019 with an aggregate grant date fair value of $5.8 million as determined by an independent third party using a Monte Carlo simulation model. The exercise price is $272.88 for 35,678 of the stock options and $294.71 for the remaining 41,189 stock options, which is equal to 125% and 135%, respectively, of the fair market value of the Company’s common stock on the grant date. The performance share award provides that the number of shares earned will be based on the Company’s achievement of certain share price levels during the five-year performance period. The performance level is $272.88 for 8,969 of the performance shares and $294.71 for the remaining 9,945 performance shares, which is equal to 125% and 135%, respectively, of the fair market value of the Company’s common stock on the grant date. Each of the performance levels were achieved in the second quarter of 2019. The performance shares and options will vest and become exercisable only upon the grantee’s continued employment with the Company through January 24, 2024. The options expire on July 22, 2024. Key assumptions used for the Monte Carlo model included a risk-free interest rate of 2.6%, a dividend yield of 0.8%, volatility of 25.8% for the stock options and volatility of 25.9% for the performance shares. As of September 30, 2019, the total unrecognized compensation cost related to all non-vested awards was $43.9 million. That cost is expected to be recognized over a weighted-average period of 2.1 years.

Earnings Per Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Earnings Per Share	8. Earnings Per Share The following table sets forth basic and diluted weighted average shares outstanding used to compute earnings per share: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (In thousands) Basic weighted average shares outstanding 37,066 36,951 37,053 36,952 Dilutive effect of stock options and restricted stock 929 877 860 907 Diluted weighted average shares outstanding 37,995 37,828 37,913 37,859 Stock options and restricted stock totaling 5,646 shares and 28,760 shares for the three months ended September 30, 2019 and 2018, respectively, and 194,672 shares and 42,159 shares for the nine months ended September 30, 2019 and 2018, respectively, were excluded from the computation of diluted earnings per share because their effect would have been antidilutive. The computation of diluted shares can vary among periods due, in part, to the change in the average price of the Company’s common stock.

Credit Agreement

Credit Agreement	9 Months Ended
	Sep. 30, 2019
Debt Disclosure [Abstract]
Credit Agreement	9. Credit Agreement In October 2015, the Company entered into a two-year amended and restated credit agreement (the “Credit Agreement”) that provided for revolving loans and letters of credit up to an aggregate of $100.0 million. The Company amended the Credit Agreement in October 2017 and extended the maturity date to October 2018. The amended Credit Agreement also provided for two additional one-year extension options and modified certain borrowing terms and covenants. Following the exercise of the first option to extend the maturity date by one year in October 2018, the Company exercised its second option in October 2019 to extend the maturity date to October 2020. Subject to satisfaction of certain specified conditions, the Company is permitted to upsize the borrowing capacity under the Credit Agreement by an additional $50.0 million. As of September 30, 2019, the Company had $1.0 million in letters of credit outstanding and $99.0 million in available borrowing capacity under the Credit Agreement. Borrowings under the Credit Agreement will bear interest at a rate per annum equal to the base rate or adjusted LIBOR plus an applicable margin that varies with the Company’s consolidated total leverage ratio. The Credit Agreement requires that the Company satisfies certain covenants, which includes leverage ratios and minimum earnings before interest, tax, depreciation and amortization (“EBITDA”) requirements. The Company was in compliance with all applicable covenants at September 30, 2019 and December 31, 2018. The Company’s existing and future domestic subsidiaries (other than any regulated subsidiary) have guaranteed the Company’s obligations under the Credit Agreement. Subject to customary exceptions and exclusions, the Company’s borrowings under the Credit Agreement are collateralized by first priority pledges (subject to permitted liens) of substantially all of the Company’s personal property assets and the personal property assets of the Company’s domestic subsidiaries that have guaranteed the Credit Agreement, including the equity interests of the Company’s domestic subsidiaries and the equity interests of certain of the Company’s foreign subsidiaries (limited, in the case of the voting equity interests of the foreign subsidiaries, to a pledge of 65% of those equity interests). If an event of default occurs, including failure to pay principal or interest due on the loan balance, a voluntary or involuntary proceeding seeking liquidation, change in control of the Company, or one or more material judgments against the Company in excess of $10.0 million, the lenders would be entitled to accelerate the borrowings under the Credit Agreement and take various other actions, including all actions permitted to be taken by a secured creditor. If certain bankruptcy events of default occur, the borrowings under the Credit Agreement will automatically accelerate.

Leases

Leases	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Leases	10. Leases The Company has operating leases for corporate offices with initial lease terms ranging from one-year to 15 years. Certain leases contain options to extend the initial term at the Company’s discretion. The Company accounts for the option to extend when it is reasonably certain of being exercised. The Company’s lease agreements do not contain any material residual value guarantees, restrictions or covenants. The following table presents the components of occupancy expense for the three and nine months ended September 30, 2019: Lease cost: Classification Three Months Ended September 30, 2019 Nine Months Ended September 30, 2019 (In thousands) Operating lease cost Occupancy $ 2,602 $ 8,003 Operating lease cost for subleased/assigned properties Other, net 707 1,863 Variable lease costs Occupancy 9 164 Sublease income subleased/assigned properties Other, net (707 ) (1,863 ) Net lease cost $ 2,611 $ 8,167 The Company determines whether an arrangement is, or includes, a lease at contract inception. Operating lease right-of-use assets and liabilities are recognized at commencement date and are initially measured based on the present value of lease payments over the defined lease term. As the Company's leases do not provide an implicit rate, the Company used its incremental borrowing rate based on the information available at the adoption date in determining the present value of lease payments. The weighted average remaining lease term and weighted average discount rate were 13.9 The following table presents the maturity of lease liabilities as of September 30, 2019: (In thousands) Remainder of 2019 $ 2,412 2020 11,238 2021 10,245 2022 9,032 2023 8,703 2024 and thereafter 96,105 Total lease payments 137,735 Less: interest 45,704 Present value of lease liabilities $ 92,031 Minimum lease commitments as of December 31, 2018 that had an initial term or remaining lease term in excess of one-year are as follows: (In thousands) 2019 $ 9,764 2020 10,919 2021 10,114 2022 9,067 2023 8,738 2024 and thereafter 95,467 $ 144,069 The Company has entered into agreements that assign the Company’s lease obligations on two properties to third parties and is contingently liable should the third parties default on future lease obligations through the lease termination dates of November 2020 and February 2022. The aggregate amount of the future lease obligations under these arrangements is $4.6 million as of September 30, 2019. In September 2019, the Company entered into a lease agreement for approximately 15,646 square feet of office space in London, commencing on December 1, 2019 and expiring on January 15, 2027. The aggregate minimum rental commitment under such lease is $7.8 million. The Company expects to record a new right-of-use asset and corresponding lease liability of approximately $6.7 million.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2019
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	11. Commitments and Contingencies Legal In the normal course of business, the Company and its subsidiaries included in the consolidated financial statements may be involved in various lawsuits, proceedings and regulatory examinations. The Company assesses its liabilities and contingencies in connection with outstanding legal proceedings, if any, utilizing the latest information available. For matters where it is probable that the Company will incur a material loss and the amount can be reasonably estimated, the Company will establish an accrual for the loss. Once established, the accrual will be adjusted to reflect any relevant developments. When a loss contingency is not both probable and estimable, the Company does not establish an accrual. Based on currently available information, the outcome of the Company’s outstanding matters is not expected to have a material adverse impact on the Company’s financial position. It is not presently possible to determine the ultimate exposure to these matters and there is no assurance that the resolution of the outstanding matters will not significantly exceed any reserves accrued by the Company. Other The Company, through two regulated subsidiaries, executes certain bond transactions between and among institutional investor and broker-dealer clients on a matched principal basis by serving as counterparty to both the buyer and the seller in trades which settle through third-party clearing brokers. Settlement typically occurs within one to two trading days after the trade date. Cash settlement of the transaction occurs upon receipt or delivery of the underlying instrument that was traded. Under securities clearing agreements with third party clearing brokers, the Company maintains collateral deposits with each clearing broker in the form of cash. The amount of the collateral deposits, which are disclosed in the Consolidated Statements of Cash Flows as restricted cash, and included in prepaid expenses and other assets in the Consolidated Statements of Financial Condition was $1.1 million and $1.2 million as of September 30, 2019 and 2018, respectively. In the normal course of business, the Company enters into contracts that contain a variety of representations, warranties and indemnification provisions. The Company’s maximum exposure under these arrangements is unknown, as this would involve future claims that may be made against the Company that have not yet occurred. However, based on experience, the Company expects the risk of loss to be remote.

Share Repurchase Program

Share Repurchase Program	9 Months Ended
	Sep. 30, 2019
Equity [Abstract]
Share Repurchase Program	12. Share Repurchase Program In September 2017, the Board of Directors authorized a fifteen-month share repurchase program for up to $100.0 million that commenced in October 2017. The expiration date of this program was subsequently extended to March 31, 2019. In January 2019, the Board of Directors authorized a new two-year share repurchase program for up to $100.0 million that commenced in April 2019. For the nine months ended September 30, 2019, the Company repurchased 43,715 shares of common stock at a cost of $11.4 million. Shares repurchased under each program will be held in treasury for future use.

Segment and Geographic Informat

Segment and Geographic Information	9 Months Ended
	Sep. 30, 2019
Segment Reporting [Abstract]
Segment and Geographic Information	13. Segment and Geographic Information The Company operates an electronic platform for the trading of fixed-income securities and provides related data, analytics, compliance tools and post-trade services. The Company considers its operations to constitute a single business segment because of the highly integrated nature of these product and services, the financial markets in which the Company competes and the Company’s worldwide business activities. The Company believes that results by geographic region or client sector are not necessarily meaningful in understanding its business. For the nine months ended September 30, 2019 and 2018, the U.K. was the only individual foreign country in which the Company had a subsidiary that accounted for 10% or more of the total revenues or total long-lived assets of the Company. Revenues and long-lived assets are attributed to a geographic area based on the location of the particular subsidiary. Long-lived assets are defined as furniture, equipment, leasehold improvements and capitalized software. Information regarding revenue for the three and nine months ended September 30, 2019 and 2018 and long-lived assets as of September 30, 2019 and December 31, 2018 was as follows: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (In thousands) Revenues United States $ 109,526 $ 85,110 $ 317,282 $ 271,833 United Kingdom 21,417 15,882 62,390 49,828 Other 654 451 1,906 1,460 Total $ 131,597 $ 101,443 $ 381,578 $ 323,121 As of September 30, 2019 December 31, 2018 (In thousands) Long-lived assets, as defined United States $ 59,146 $ 55,200 United Kingdom 7,355 7,787 Other 30 23 Total $ 66,531 $ 63,010

Acquisition

Acquisition	9 Months Ended
	Sep. 30, 2019
Business Combinations [Abstract]
Acquisition	14. Acquisition On August 12, 2019, the Company entered into an agreement to purchase all of the outstanding equity interests of LiquidityEdge LLC (“LiquidityEdge”). LiquidityEdge operates an electronic platform for trading U.S. Treasuries. The aggregate purchase price is $150.0 million, comprised of $100.0 million in cash and $50.0 million in the Company’s common stock, subject to customary purchase price adjustments. The Company expects to complete the acquisition of LiquidityEdge in the fourth quarter of 2019.

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The consolidated financial statements include the accounts of the Company and its subsidiaries. All intercompany transactions and balances have been eliminated. These consolidated financial statements are unaudited and should be read in conjunction with the audited consolidated financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2018. The consolidated financial information as of December 31, 2018 has been derived from audited financial statements not included herein. These unaudited consolidated financial statements are prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) and the rules and regulations of the U.S. Securities and Exchange Commission (“SEC”) with respect to Form 10-Q and reflect all adjustments that, in the opinion of management, are normal and recurring, and that are necessary for a fair statement of the results for the interim periods presented. In accordance with such rules and regulations, certain disclosures that are normally included in annual financial statements have been omitted. Interim period operating results may not be indicative of the operating results for a full year.
Accounting Pronouncements, Recently Adopted	Accounting Pronouncements, Recently Adopted In February 2016, the Financial Accounting Standards Board (“FASB”) issued ASU 2016-02, “Leases” (“ASU 2016-02”) requiring lessees to recognize lease assets and lease liabilities on the balance sheet for those leases previously classified as operating leases with lease terms greater than 12 months. The Company adopted ASU 2016-02 effective January 1, 2019 using a modified retrospective transition approach and will not restate comparative periods. In addition, the Company elected the package of practical expedients permitted under the transition guidance within the new standard which allowed it to carry forward the historical lease classification. In August 2018, the FASB issued ASU 2018-15, “Intangibles—Goodwill and Other—Internal-Use Software: Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract” (“ASU 2018-15”). The standard requires the capitalization of implementation costs incurred in a cloud computing arrangement to be aligned with the requirements for capitalizing costs incurred to develop or obtain internal-use software. The updated guidance is effective for annual and interim reporting periods beginning after December 15, 2019, with early adoption permitted. The Company adopted ASU 2018-15 effective July 1, 2019 on a prospective basis. The Company completed its analysis and the adoption of this guidance did not have a material impact on the Company’s Consolidated Financial Statements.
Accounting Pronouncements, Not Yet Adopted as of March 31, 2019	Accounting Pronouncements, Not Yet Adopted as of September 30, 2019 In January 2017, the FASB issued ASU 2017-04, “Intangibles-Goodwill and Other” (“ASU 2017-04”). ASU 2017-04 simplifies the testing for goodwill impairment. The guidance will be effective for the Company beginning January 1, 2020 and early adoption is permitted and should be applied prospectively. The adoption of this guidance is not expected to have a material effect on the Company’s Consolidated Financial Statements.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash and cash equivalents includes cash and money market instruments that are primarily maintained at one major global bank. Given this concentration, the Company is exposed to certain credit risk in relation to its deposits at this bank. The Company defines cash equivalents as short-term interest-bearing investments with maturities at the time of purchase of three months or less.
Investments	Investments The Company determines the appropriate classification of securities at the time of purchase which are recorded in the Consolidated Statements of Financial Condition on the trade date. Securities are classified as available-for-sale or trading. The Company’s available-for-sale investments are comprised of investment grade corporate debt securities. Available-for-sale investments are carried at fair value with the unrealized gains or losses reported in accumulated other comprehensive loss in the Consolidated Statements of Financial Condition. Trading investments include investment grade corporate debt securities and U.S. Treasuries and are carried at fair value, with realized and unrealized gains or losses included in other income in the Consolidated Statements of Operations. The Company assesses whether an other-than-temporary impairment loss on the available-for-sale investments has occurred due to declines in fair value or other market conditions. The portion of an other-than-temporary impairment related to credit loss is recorded as a charge in the Consolidated Statements of Operations. The remainder is recognized in accumulated other comprehensive loss if the Company does not intend to sell the security and it is more likely than not that the Company will not be required to sell the security prior to recovery. No charges for other-than-temporary losses were recorded during the three month and nine month periods ended September 30, 2019 and 2018, respectively.
Fair Value Financial Instruments	Fair Value Financial Instruments Fair value is defined as “the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date.” A three-tiered hierarchy for determining fair value has been established that prioritizes inputs to valuation techniques used in fair value calculations. The three levels of inputs are defined as Level 1 (unadjusted quoted prices for identical assets or liabilities in active markets), Level 2 (inputs that are observable in the marketplace other than those inputs classified in Level 1) and Level 3 (inputs that are unobservable in the marketplace). The Company’s financial assets and liabilities measured at fair value on a recurring basis consist of its money market funds, securities available-for-sale, trading securities and foreign currency forward contracts. All other financial instruments are short-term in nature and the carrying amount is reported on the Consolidated Statements of Financial Condition at approximate fair value.
Allowance for Doubtful Accounts	Allowance for Doubtful Accounts All accounts receivable have contractual maturities of less than one year and are derived from trading-related fees and commissions and revenues from products and services. The Company continually monitors collections and payments from its customers and maintains an allowance for doubtful accounts. The allowance for doubtful accounts is based upon the historical collection experience and specific collection issues that have been identified. Additions to the allowance for doubtful accounts are charged to bad debt expense, which is included in general and administrative expense in the Company’s Consolidated Statements of Operations.
Depreciation and Amortization	Depreciation and Amortization Fixed assets are carried at cost less accumulated depreciation. The Company uses the straight-line method of depreciation over three to seven years. The Company amortizes leasehold improvements on a straight-line basis over the lesser of the life of the improvement or the remaining term of the lease.
Software Development Costs	Software Development Costs The Company capitalizes certain costs associated with the development of internal use software, including, among other items, employee compensation and related benefits and third party consulting costs at the point at which the conceptual formulation, design and testing of possible software project alternatives have been completed. Once the product is ready for its intended use, such costs are amortized on a straight-line basis over three years. The Company reviews the amounts capitalized for impairment whenever events or changes in circumstances indicate that the carrying amounts of the assets may not be recoverable.
Cloud Computing Costs	Cloud Computing Costs The Company capitalizes certain costs associated with cloud computing arrangements, including, among other items, employee compensation and related benefits and third party consulting costs that are part of the application development stage. These costs are setup as a pre-paid asset on the balance sheet and are amortized over the period of the hosting service contract. The Company reviews the amounts capitalized for impairment whenever events or changes in circumstances indicate that the carrying amounts of the assets may not be recoverable.
Cash Provided as Collateral	Cash Provided as Collateral Cash is provided as collateral for broker-dealer clearing accounts. Cash provided as collateral is included in prepaid expenses and other assets in the Consolidated Statements of Financial Condition.
Foreign Currency Translation and Forward Contracts	Foreign Currency Translation and Forward Contracts Assets and liabilities denominated in foreign currencies are translated using exchange rates at the end of the period; revenues and expenses are translated at average monthly rates. Gains and losses on foreign currency translation are a component of accumulated other comprehensive loss in the Consolidated Statements of Financial Condition. Transaction gains and losses are recorded in other, net in the Consolidated Statements of Operations. The Company enters into foreign currency forward contracts to hedge its net investment in its U.K. subsidiaries. Gains and losses on these transactions are included in accumulated other comprehensive loss in the Consolidated Statements of Financial Condition.
Revenue Recognition	Revenue Recognition The Company’s classification of revenues in the Consolidated Statements of Operations represents revenues from contracts with customers disaggregated by type of revenue. The Company has four revenue streams as described below. Commission Revenue – The Company charges its broker-dealer clients variable transaction fees for trades executed on its platform and, under certain plans, distribution fees or monthly minimum fees to use the platform for a particular product area. Variable transaction fees are generally calculated as a percentage of the notional dollar volume of bonds traded on the platform and vary based on the type, size, yield and maturity of the bond traded. Under the Company’s disclosed trading transaction fee plans, bonds that are more actively traded or that have shorter maturities are generally charged lower commissions, while bonds that are less actively traded or that have longer maturities generally command higher commissions. Variable transaction fees, distribution fees and unused monthly fee commitments are invoiced and recorded on a monthly basis. For trades that the Company executes between and among institutional investor and broker-dealer clients on a matched principal basis by serving as counterparty to both the buyer and the seller, the Company earns its commission through the difference in price between the two trades. The commission is collected upon settlement of the trade, which typically occurs within one to two trading days after the trade date. The following table presents commission revenue by fee type for the three and nine months ended September 30, 2019 and 2018: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (In thousands) Commission revenue by fee type Variable transaction fees Disclosed trading $ 69,541 $ 49,727 $ 202,905 $ 172,443 Open Trading - matched principal trading 26,444 16,228 72,934 44,943 Total variable transaction fees 95,985 65,955 275,839 217,386 Distribution fees and unused minimum fees 23,884 24,558 70,914 72,012 Total commissions $ 119,869 $ 90,513 $ 346,753 $ 289,398 Information services – Information services includes data licensed to the Company’s broker-dealer clients, institutional investor clients and data-only subscribers; professional and consulting services; technology software licenses; and maintenance and support services. The nature and timing of each performance obligation may vary as these contracts are either subscription based services transferred over time or one-time services that are transferred at a point in time. Revenues for services transferred over time are recognized ratably over the contract period as the Company’s performance obligation is met whereas revenues for services transferred at a point in time are recognized in the period the services are provided. Customers are generally billed monthly, quarterly, or annually; revenues billed in advance are deferred and recognized ratably over the contract period. The following table presents information services revenue by timing of recognition for the three and nine months ended September 30, 2019 and 2018: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (In thousands) Information services revenue by timing of recognition Services transferred over time $ 7,203 $ 7,029 $ 21,472 $ 20,652 Services transferred at a point in time 490 145 743 518 Total information services revenues $ 7,693 $ 7,174 $ 22,215 $ 21,170 Post-trade services – Post-trade services revenue is generated from regulatory transaction reporting, trade publication and trade matching services. Customers are generally billed monthly in arrears and revenue is recognized in the period transactions are processed. Revenues billed in advance are deferred and recognized ratably over the contract period. The Company also generates one-time implementation fees for onboarding clients which are invoiced and recognized in the period the implementation is completed. The following table presents post-trade services revenue by timing of recognition for the three and nine months ended September 30, 2019 and 2018: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (In thousands) Post-trade services revenue by timing of recognition Services transferred over time $ 3,775 $ 3,463 $ 11,811 $ 11,370 Services transferred at a point in time 9 12 29 301 Total post-trade services revenues $ 3,784 $ 3,475 $ 11,840 $ 11,671 Other revenues – Other revenues primarily includes revenue from telecommunications line charges to broker-dealer clients. Contract liabilities consist of deferred revenues that the Company records when cash payments are received or due in advance of services to be performed. The revenue recognized from contract liabilities and the remaining balance is shown below: December 31, 2018 Payments received in advance of services to be performed Revenue recognized for services performed during the period Foreign Currency Translation September 30, 2019 (In thousands) Information services $ 1,959 $ 6,030 $ (5,437 ) $ — $ 2,552 Post-trade services 851 9,538 (9,180 ) (30 ) 1,179 Total deferred revenue $ 2,810 $ 15,568 $ (14,617 ) $ (30 ) $ 3,731 The majority of the Company’s contracts are short-term in nature with durations of less than one-year. For contracts extending beyond one year, the aggregate amount of the transaction price allocated to remaining performance obligations was $27.9 million as of September 30, 2019. The Company expects to recognize revenue associated with the remaining performance obligations over the next 29 months.
Stock-Based Compensation	Stock-Based Compensation The Company measures and recognizes compensation expense for all share-based payment awards based on their estimated fair values measured as of the grant date. These costs are recognized as an expense in the Consolidated Statements of Operations over the requisite service period, which is typically the vesting period, with an offsetting increase to additional paid-in capital. Forfeitures are recognized as they occur.
Income Taxes	Income Taxes Income taxes are accounted for using the asset and liability method. 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. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. A valuation allowance is recognized against deferred tax assets if it is more likely than not that such assets will not be realized in future years. The Company recognizes interest and penalties related to unrecognized tax benefits in general and administrative expenses in the Consolidated Statements of Operations. Effective upon the Company’s adoption of ASU 2016-09, all tax effects related to share-based payments are recorded through tax expense in the periods during which the awards are exercised or vest.
Business Combinations, Goodwill and Intangible Assets	Business Combinations, Goodwill and Intangible Assets Business combinations are accounted for under the purchase method of accounting. The total cost of an acquisition is allocated to the underlying net assets based on their respective estimated fair values. The excess of the purchase price over the estimated fair values of the net assets acquired is recorded as goodwill. Determining the fair value of certain assets acquired and liabilities assumed requires judgment and often involves the use of significant estimates and assumptions, including assumptions with respect to future cash flows, discount rates, growth rates and asset lives. The Company operates as a single reporting unit. Subsequent to an acquisition, goodwill no longer retains its identification with a particular acquisition, but instead becomes identifiable with the entire reporting unit. As a result, all of the fair value of the Company is available to support the value of goodwill. An impairment review of goodwill is performed on an annual basis, at year-end, or more frequently if circumstances change. Intangible assets with definite lives, including purchased technologies, customer relationships and other intangible assets, are amortized on a straight-line basis over their estimated useful lives, ranging from three to 15 years. Intangible assets are assessed for impairment when events or circumstances indicate the existence of a possible impairment.
Earnings Per Share	Earnings Per Share Basic earnings per share is computed by dividing the net income attributable to common stock by the weighted-average number of shares of common stock outstanding during the period. For purposes of computing diluted earnings per share, the weighted-average shares outstanding of common stock reflects the dilutive effect that could occur if convertible securities or other contracts to issue common stock were converted into or exercised for common stock.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.

Significant Accounting Polici_3

Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Summary of Commission Revenue by Fee Type	The following table presents commission revenue by fee type for the three and nine months ended September 30, 2019 and 2018: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (In thousands) Commission revenue by fee type Variable transaction fees Disclosed trading $ 69,541 $ 49,727 $ 202,905 $ 172,443 Open Trading - matched principal trading 26,444 16,228 72,934 44,943 Total variable transaction fees 95,985 65,955 275,839 217,386 Distribution fees and unused minimum fees 23,884 24,558 70,914 72,012 Total commissions $ 119,869 $ 90,513 $ 346,753 $ 289,398
Summary of Information Services Revenue by Timing of Recognition	The following table presents information services revenue by timing of recognition for the three and nine months ended September 30, 2019 and 2018: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (In thousands) Information services revenue by timing of recognition Services transferred over time $ 7,203 $ 7,029 $ 21,472 $ 20,652 Services transferred at a point in time 490 145 743 518 Total information services revenues $ 7,693 $ 7,174 $ 22,215 $ 21,170
Summary of Post-Trade Services Revenue by Timing of Recognition	The following table presents post-trade services revenue by timing of recognition for the three and nine months ended September 30, 2019 and 2018: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (In thousands) Post-trade services revenue by timing of recognition Services transferred over time $ 3,775 $ 3,463 $ 11,811 $ 11,370 Services transferred at a point in time 9 12 29 301 Total post-trade services revenues $ 3,784 $ 3,475 $ 11,840 $ 11,671
Summary of Revenue Recognized from Contract Liabilities and Remaining Balance	The revenue recognized from contract liabilities and the remaining balance is shown below: December 31, 2018 Payments received in advance of services to be performed Revenue recognized for services performed during the period Foreign Currency Translation September 30, 2019 (In thousands) Information services $ 1,959 $ 6,030 $ (5,437 ) $ — $ 2,552 Post-trade services 851 9,538 (9,180 ) (30 ) 1,179 Total deferred revenue $ 2,810 $ 15,568 $ (14,617 ) $ (30 ) $ 3,731

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Valuation of Company's Assets and Liabilities Measured at Fair Value	The following table summarizes the valuation of the Company’s assets and liabilities measured at fair value as categorized based on the hierarchy described in Note 2. Level 1 Level 2 Level 3 Total (In thousands) As of September 30, 2019 Money market funds $ 163,734 $ — $ — $ 163,734 Securities available-for-sale Corporate debt — 140,812 — 140,812 Trading securities Corporate debt — 33,697 — 33,697 U.S. Treasuries — 55,248 — 55,248 Mutual funds held in rabbi trust — 5,868 — 5,868 Foreign currency forward position — 231 — 231 Total $ 163,734 $ 235,856 $ — $ 399,590 As of December 31, 2018 Money market funds $ 112,529 $ — $ — $ 112,529 Securities available-for-sale Corporate debt — 146,966 — 146,966 Trading securities Corporate debt — 71,861 — 71,861 U.S. Treasuries — 17,178 — 17,178 Mutual funds held in rabbi trust — 4,100 — 4,100 Foreign currency forward position — (1,021 ) — (1,021 ) Total $ 112,529 $ 239,084 $ — $ 351,613
Summary of Foreign Currency Forward Contracts	A summary of the Company’s foreign currency forward position is as follows: As of September 30, 2019 December 31, 2018 (In thousands) Notional value $ 134,907 $ 106,306 Fair value of notional 134,676 107,327 Fair value of the asset (liability) $ 231 $ (1,021 )
Summary of Company's Investments	The following is a summary of the Company’s investments: Amortized cost Gross unrealized gains Gross unrealized losses Estimated fair value (In thousands) As of September 30, 2019 Securities available-for-sale Corporate debt $ 140,104 $ 732 $ (24 ) $ 140,812 Trading securities Corporate debt 33,676 30 (9 ) 33,697 U.S. Treasuries 54,661 587 — 55,248 Mutual funds held in rabbi trust 5,173 695 — 5,868 Total trading securities 93,510 1,312 (9 ) 94,813 Total investments $ 233,614 $ 2,044 $ (33 ) $ 235,625 As of December 31, 2018 Securities available-for-sale Corporate debt $ 147,556 $ 27 $ (617 ) $ 146,966 Trading securities Corporate debt 72,274 8 (421 ) 71,861 U.S. Treasuries 16,953 225 — 17,178 Mutual funds held in rabbi trust 4,347 — (247 ) 4,100 Total trading securities 93,574 233 (668 ) 93,139 Total investments $ 241,130 $ 260 $ (1,285 ) $ 240,105
Summary of Fair Value of Investments Based upon Contractual Maturities	The following table summarizes the fair value of the investments based upon the contractual maturities: As of September 30, 2019 December 31, 2018 (In thousands) Less than one year $ 116,365 $ 134,255 Due in 1 - 5 years 119,260 105,850 Total $ 235,625 $ 240,105
Fair Values and Unrealized Losses on Investments	The following table provides fair values and unrealized losses on investments and by the aging of the securities’ continuous unrealized loss position as of September 30, 2019 and December 31, 2018: Less than Twelve Months Twelve Months or More Total Estimated fair value Gross unrealized losses Estimated fair value Gross unrealized losses Estimated fair value Gross unrealized losses (In thousands) As of September 30, 2019 Corporate debt $ 21,666 $ (19 ) $ 16,916 $ (14 ) $ 38,582 $ (33 ) As of December 31, 2018 Corporate debt $ 80,282 $ (256 ) $ 87,028 $ (782 ) $ 167,310 $ (1,038 )

Goodwill and Intangible Assets

Goodwill and Intangible Assets (Tables)	9 Months Ended
	Sep. 30, 2019
Goodwill And Intangible Assets Disclosure [Abstract]
Summary of Company's Intangible Assets	Goodwill and intangible assets with indefinite lives was $59.7 million as of both September 30, 2019 and December 31, 2018. Intangible assets that are subject to amortization, including the related accumulated amortization, are comprised of the following: September 30, 2019 December 31, 2018 Cost Accumulated amortization Net carrying amount Cost Accumulated amortization Net carrying amount (In thousands) Technology $ 5,770 $ (5,770 ) $ — $ 5,770 $ (5,770 ) $ — Customer relationships 5,627 (2,952 ) 2,675 5,634 (2,672 ) 2,962 Non-competition agreements 380 (380 ) — 380 (380 ) — Tradenames 370 (370 ) — 370 (370 ) — Total $ 12,147 $ (9,472 ) $ 2,675 $ 12,154 $ (9,192 ) $ 2,962

Income Taxes (Tables)

Income Taxes (Tables)	9 Months Ended
	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Schedule of Provision for Income Taxes	The provision for income taxes consists of the following: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Current: (In thousands) Federal $ 9,628 $ 6,358 $ 26,100 $ 23,119 State and local 1,865 1,619 5,215 5,616 Foreign 3,385 2,502 9,429 6,036 Total current provision 14,878 10,479 40,744 34,771 Deferred: Federal (1,231 ) (663 ) 195 (321 ) State and local (214 ) (136 ) 4 (107 ) Foreign (97 ) (477 ) (105 ) 656 Total deferred provision (1,542 ) (1,276 ) 94 228 Provision for income taxes $ 13,336 $ 9,203 $ 40,838 $ 34,999

Stock-Based Compensation Plans

Stock-Based Compensation Plans (Tables)	9 Months Ended
	Sep. 30, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation Expense	Total stock-based compensation expense was as follows: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (In thousands) Employees $ 7,706 $ 3,654 $ 18,267 $ 10,739 Non-employee directors 238 296 802 812 Total stock-based compensation $ 7,944 $ 3,950 $ 19,069 $ 11,551

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2019
Earnings Per Share [Abstract]
Basic and Diluted Weighted Average Shares Outstanding Used to Compute Earnings Per Share	The following table sets forth basic and diluted weighted average shares outstanding used to compute earnings per share: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (In thousands) Basic weighted average shares outstanding 37,066 36,951 37,053 36,952 Dilutive effect of stock options and restricted stock 929 877 860 907 Diluted weighted average shares outstanding 37,995 37,828 37,913 37,859

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2019
Leases [Abstract]
Schedule of Components of Occupancy Expense	The following table presents the components of occupancy expense for the three and nine months ended September 30, 2019: Lease cost: Classification Three Months Ended September 30, 2019 Nine Months Ended September 30, 2019 (In thousands) Operating lease cost Occupancy $ 2,602 $ 8,003 Operating lease cost for subleased/assigned properties Other, net 707 1,863 Variable lease costs Occupancy 9 164 Sublease income subleased/assigned properties Other, net (707 ) (1,863 ) Net lease cost $ 2,611 $ 8,167
Schedule of Maturity of Lease Liabilities	The following table presents the maturity of lease liabilities as of September 30, 2019: (In thousands) Remainder of 2019 $ 2,412 2020 11,238 2021 10,245 2022 9,032 2023 8,703 2024 and thereafter 96,105 Total lease payments 137,735 Less: interest 45,704 Present value of lease liabilities $ 92,031
Summary of Minimum Lease Commitments	Minimum lease commitments as of December 31, 2018 that had an initial term or remaining lease term in excess of one-year are as follows: (In thousands) 2019 $ 9,764 2020 10,919 2021 10,114 2022 9,067 2023 8,738 2024 and thereafter 95,467 $ 144,069

Segment and Geographic Inform_2

Segment and Geographic Information (Tables)	9 Months Ended
	Sep. 30, 2019
Segment Reporting [Abstract]
Summary of Revenue and Long-lived Assets	Information regarding revenue for the three and nine months ended September 30, 2019 and 2018 and long-lived assets as of September 30, 2019 and December 31, 2018 was as follows: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (In thousands) Revenues United States $ 109,526 $ 85,110 $ 317,282 $ 271,833 United Kingdom 21,417 15,882 62,390 49,828 Other 654 451 1,906 1,460 Total $ 131,597 $ 101,443 $ 381,578 $ 323,121 As of September 30, 2019 December 31, 2018 (In thousands) Long-lived assets, as defined United States $ 59,146 $ 55,200 United Kingdom 7,355 7,787 Other 30 23 Total $ 66,531 $ 63,010

Organization and Principal Bu_2

Organization and Principal Business Activity - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2019Institutional_Investor_and_Broker-dealer_Firm
Accounting Policies [Line Items]
Date of incorporation	Apr. 11, 2000
Minimum [Member]
Accounting Policies [Line Items]
Number of institutional investor and broker-dealer firms	1,600

Significant Accounting Polici_4

Significant Accounting Policies - Additional Information (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)Revenue	Sep. 30, 2018USD ($)	Jan. 01, 2019USD ($)
Significant Accounting Policies [Line Items]
Operating lease liabilities	$ 92,031,000		$ 92,031,000
Operating lease right-of-use assets	75,390,000		$ 75,390,000
Maximum maturity period for classification of investments as cash equivalents			3 months
Investments other-than-temporary losses	$ 0	$ 0	$ 0	$ 0
Number of revenue streams | Revenue			4
Description of commission revenue			For trades that the Company executes between and among institutional investor and broker-dealer clients on a matched principal basis by serving as counterparty to both the buyer and the seller, the Company earns its commission through the difference in price between the two trades.
Settlement days of bond transaction			Within one to two trading days
Maximum [Member]
Significant Accounting Policies [Line Items]
Contractual maturities accounts receivable			1 year
Estimated useful life of fixed assets			7 years
Maximum [Member] | Business Combinations [Member]
Significant Accounting Policies [Line Items]
Estimated life of intangible assets			15 years
Minimum [Member]
Significant Accounting Policies [Line Items]
Estimated useful life of fixed assets			3 years
Minimum [Member] | Business Combinations [Member]
Significant Accounting Policies [Line Items]
Estimated life of intangible assets			3 years
Minimum [Member] | Internally Developed Software [Member]
Significant Accounting Policies [Line Items]
Estimated life of intangible assets			3 years
ASU 2016-02
Significant Accounting Policies [Line Items]
Operating lease liabilities					$ 91,200,000
Operating lease right-of-use assets					79,500,000
Deferred rent liability					$ 11,700,000

Significant Accounting Polici_5

Significant Accounting Policies - Summary of Commission Revenue by Fee Type (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Commission revenue by fee type
Revenues	$ 131,597	$ 101,443	$ 381,578	$ 323,121
Commissions [Member]
Commission revenue by fee type
Disclosed trading	69,541	49,727	202,905	172,443
Open Trading - matched principal trading	26,444	16,228	72,934	44,943
Total variable transaction fees	95,985	65,955	275,839	217,386
Distribution fees and unused minimum fees	23,884	24,558	70,914	72,012
Revenues	$ 119,869	$ 90,513	$ 346,753	$ 289,398

Significant Accounting Polici_6

Significant Accounting Policies - Summary of Information Services Revenue by Timing of Recognition (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Significant Accounting Policies [Line Items]
Revenues	$ 131,597	$ 101,443	$ 381,578	$ 323,121
Information Services [Member]
Significant Accounting Policies [Line Items]
Revenues	7,693	7,174	22,215	21,170
Information Services [Member] | Transferred over Time [Member]
Significant Accounting Policies [Line Items]
Revenues	7,203	7,029	21,472	20,652
Information Services [Member] | Transferred at a Point in Time [Member]
Significant Accounting Policies [Line Items]
Revenues	$ 490	$ 145	$ 743	$ 518

Significant Accounting Polici_7

Significant Accounting Policies - Summary of Post-Trade Services Revenue by Timing of Recognition (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Significant Accounting Policies [Line Items]
Revenues	$ 131,597	$ 101,443	$ 381,578	$ 323,121
Post-trade Services [Member]
Significant Accounting Policies [Line Items]
Revenues	3,784	3,475	11,840	11,671
Post-trade Services [Member] | Transferred over Time [Member]
Significant Accounting Policies [Line Items]
Revenues	3,775	3,463	11,811	11,370
Post-trade Services [Member] | Transferred at a Point in Time [Member]
Significant Accounting Policies [Line Items]
Revenues	$ 9	$ 12	$ 29	$ 301

Significant Accounting Polici_8

Significant Accounting Policies - Summary of Revenue Recognized from Contract Liabilities and Remaining Balance (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2019USD ($)
Significant Accounting Policies [Line Items]
Deferred revenues, beginning balance	$ 2,810
Payments received in advance of services to be performed	15,568
Revenue recognized for services performed during the period	(14,617)
Foreign Currency Translation	(30)
Deferred revenues, ending balance	3,731
Information Services [Member]
Significant Accounting Policies [Line Items]
Deferred revenues, beginning balance	1,959
Payments received in advance of services to be performed	6,030
Revenue recognized for services performed during the period	(5,437)
Deferred revenues, ending balance	2,552
Post-trade Services [Member]
Significant Accounting Policies [Line Items]
Deferred revenues, beginning balance	851
Payments received in advance of services to be performed	9,538
Revenue recognized for services performed during the period	(9,180)
Foreign Currency Translation	(30)
Deferred revenues, ending balance	$ 1,179

Significant Accounting Polici_9

Significant Accounting Policies - Additional Information (Detail 1) - Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2019-07-01 $ in Millions	Sep. 30, 2019USD ($)
Significant Accounting Policies [Line Items]
Aggregate amount of transaction price allocated to remaining performance obligations	$ 27.9
Expected time to recognize revenue for remaining performance obligation	29 months

Net Capital Requirements - Addi

Net Capital Requirements - Additional Information (Detail) $ in Millions	Sep. 30, 2019USD ($)
Brokers And Dealers [Abstract]
Aggregate net capital and financial resources in excess of required level	$ 182.9
Aggregate net capital and financial resources, minimum capital requirement	$ 14.3

Fair Value Measurements - Valua

Fair Value Measurements - Valuation of Company's Assets and Liabilities Measured at Fair Value (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Money market funds	$ 163,734	$ 112,529
Trading securities	94,813	93,139
Foreign currency forward position	231	(1,021)
Assets Fair Value Total	399,590	351,613
Corporate Debt [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities available-for-sale	140,812	146,966
Trading securities	33,697	71,861
U.S. Treasuries [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Trading securities	55,248	17,178
Mutual Funds Held In Rabbi Trust [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Trading securities	5,868	4,100
Foreign Currency Forward Position [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Foreign currency forward position	231	(1,021)
Level 1 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Money market funds	163,734	112,529
Assets Fair Value Total	163,734	112,529
Level 2 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets Fair Value Total	235,856	239,084
Level 2 [Member] | Corporate Debt [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Securities available-for-sale	140,812	146,966
Trading securities	33,697	71,861
Level 2 [Member] | U.S. Treasuries [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Trading securities	55,248	17,178
Level 2 [Member] | Mutual Funds Held In Rabbi Trust [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Trading securities	5,868	4,100
Level 2 [Member] | Foreign Currency Forward Position [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Foreign currency forward position	$ 231	$ (1,021)

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Hedge derivative expiration period	1 month
Proceeds from the sales and maturities of securities available-for-sale	$ 238.5	$ 308.3

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Foreign Currency Forward Contracts (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Derivatives Fair Value [Line Items]
Fair value of the asset (liability)	$ 231	$ (1,021)
Foreign Currency Forward Position [Member]
Derivatives Fair Value [Line Items]
Notional value	134,907	106,306
Fair value of notional	134,676	107,327
Fair value of the asset (liability)	$ 231	$ (1,021)

Fair Value Measurements - Sum_2

Fair Value Measurements - Summary of Company's Investments (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Schedule Of Available For Sale Securities [Line Items]
Trading securities, Amortized cost	$ 93,510	$ 93,574
Trading securities, Gross unrealized gains	1,312	233
Trading securities, Gross unrealized losses	(9)	(668)
Trading securities, Estimated fair value	94,813	93,139
Investments, Amortized cost	233,614	241,130
Investments, Gross unrealized gains	2,044	260
Investments, Gross unrealized losses	(33)	(1,285)
Investments, Estimated fair value	235,625	240,105
Corporate Debt [Member]
Schedule Of Available For Sale Securities [Line Items]
Securities available-for-sale, Amortized cost	140,104	147,556
Securities available-for-sale, Gross unrealized gains	732	27
Securities available-for-sale, Gross unrealized losses	(24)	(617)
Securities available-for-sale, Estimated fair value	140,812	146,966
Trading securities, Amortized cost	33,676	72,274
Trading securities, Gross unrealized gains	30	8
Trading securities, Gross unrealized losses	(9)	(421)
Trading securities, Estimated fair value	33,697	71,861
U.S. Treasuries [Member]
Schedule Of Available For Sale Securities [Line Items]
Trading securities, Amortized cost	54,661	16,953
Trading securities, Gross unrealized gains	587	225
Trading securities, Estimated fair value	55,248	17,178
Mutual Funds Held In Rabbi Trust [Member]
Schedule Of Available For Sale Securities [Line Items]
Trading securities, Amortized cost	5,173	4,347
Trading securities, Gross unrealized gains	695
Trading securities, Gross unrealized losses		(247)
Trading securities, Estimated fair value	$ 5,868	$ 4,100

Fair Value Measurements - Sum_3

Fair Value Measurements - Summary of Fair Value of Investments Based upon Contractual Maturities (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Less than one year	$ 116,365	$ 134,255
Due in 1 - 5 years	119,260	105,850
Total	$ 235,625	$ 240,105

Fair Value Measurements - Fair

Fair Value Measurements - Fair Values and Unrealized Losses on Investments (Detail) - Corporate Debt [Member] - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Schedule Of Available For Sale Securities [Line Items]
Less than Twelve Months, Estimated fair value	$ 21,666	$ 80,282
Less than Twelve Months, Gross unrealized losses	(19)	(256)
Twelve Months or More, Estimated fair value	16,916	87,028
Twelve Months or More, Gross unrealized losses	(14)	(782)
Estimated fair value, Total	38,582	167,310
Gross unrealized losses, Total	$ (33)	$ (1,038)

Goodwill and Intangible Asset_2

Goodwill and Intangible Assets - Additional Information (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Goodwill [Line Items]
Goodwill and intangible assets with indefinite lives	$ 62,387		$ 62,675
Amortization expense associated with identifiable intangible assets	300	$ 300
Estimated total amortization expense 2019	400
Estimated total amortization expense 2020	400
Estimated total amortization expense 2021	400
Estimated total amortization expense 2022	400
Estimated total amortization expense 2023	300
Indefinite-lived Intangible Assets [Member]
Goodwill [Line Items]
Goodwill and intangible assets with indefinite lives	$ 59,700		$ 59,700

Goodwill and Intangible Asset_3

Goodwill and Intangible Assets - Summary of Company's Intangible Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Finite Lived Intangible Assets [Line Items]
Cost	$ 12,147	$ 12,154
Accumulated amortization	(9,472)	(9,192)
Net carrying amount	2,675	2,962
Technology [Member]
Finite Lived Intangible Assets [Line Items]
Cost	5,770	5,770
Accumulated amortization	(5,770)	(5,770)
Customer Relationships [Member]
Finite Lived Intangible Assets [Line Items]
Cost	5,627	5,634
Accumulated amortization	(2,952)	(2,672)
Net carrying amount	2,675	2,962
Non-Competition Agreements [Member]
Finite Lived Intangible Assets [Line Items]
Cost	380	380
Accumulated amortization	(380)	(380)
Tradenames - Finite Life [Member]
Finite Lived Intangible Assets [Line Items]
Cost	370	370
Accumulated amortization	$ (370)	$ (370)

Income Taxes - Schedule of Prov

Income Taxes - Schedule of Provision for Income Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Current:
Federal	$ 9,628	$ 6,358	$ 26,100	$ 23,119
State and local	1,865	1,619	5,215	5,616
Foreign	3,385	2,502	9,429	6,036
Total current provision	14,878	10,479	40,744	34,771
Deferred:
Federal	(1,231)	(663)	195	(321)
State and local	(214)	(136)	4	(107)
Foreign	(97)	(477)	(105)	656
Total deferred provision	(1,542)	(1,276)	94	228
Provision for income taxes	$ 13,336	$ 9,203	$ 40,838	$ 34,999

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Schedule Of Pre Tax Income [Line Items]
Excess tax benefits on share based payments	$ 3.5	$ 1.7	$ 7	$ 3.7
New York State [Member] | Earliest Tax Year [Member]
Schedule Of Pre Tax Income [Line Items]
Income tax year under examination			2010
New York State [Member] | Latest Tax Year [Member]
Schedule Of Pre Tax Income [Line Items]
Income tax year under examination			2017

Stock-Based Compensation Plan_2

Stock-Based Compensation Plans - Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	$ 7,944	$ 3,950	$ 19,069	$ 11,551
Employees [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	7,706	3,654	18,267	10,739
Non-Employee Directors [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation	$ 238	$ 296	$ 802	$ 812

Stock-Based Compensation Plan_3

Stock-Based Compensation Plans - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	9 Months Ended
	Jan. 31, 2019	Sep. 30, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation costs related to non-vested		$ 43.9
Weighted-average period over which cost is expected to be recognized		2 years 1 month 6 days
Employees [Member] | Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of non-option equity instruments granted during the period		97,244
Weighted-average grant date fair value per share		$ 242.74
Employees [Member] | Performance Based Share [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of non-option equity instruments granted during the period		16,716
Number of stock option equity instruments granted during the period		82,474
Weighted-average fair value each option granted		$ 38.83
Weighted-average grant date fair value per share		$ 224.13
President and Chief Operating Officer [Member] | Performance Based Share [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of non-option equity instruments granted during the period	18,914
Grant date fair value	$ 5.8
Share-based compensation arrangement by share-based payment award award vesting date	Jan. 24, 2024
Fair value assumptions, Risk free interest rate	2.60%
Fair value assumptions, Dividend yield rate	0.80%
Fair value assumptions, Volatility rate	25.90%
Performance period	5 years
President and Chief Operating Officer [Member] | Performance Based Share [Member] | Range One [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of non-option equity instruments granted during the period	8,969
Weighted-average grant date fair value per share	$ 272.88
Percentage of fair market value of the common stock on the grant date	125.00%
President and Chief Operating Officer [Member] | Performance Based Share [Member] | Range Two [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of non-option equity instruments granted during the period	9,945
Weighted-average grant date fair value per share	$ 294.71
Percentage of fair market value of the common stock on the grant date	135.00%
President and Chief Operating Officer [Member] | Incentive Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of stock option equity instruments granted during the period	76,868
Grant date fair value	$ 5.8
Share-based compensation arrangement by share-based payment award award vesting date	Jan. 24, 2024
Fair value assumptions, Risk free interest rate	2.60%
Fair value assumptions, Dividend yield rate	0.80%
Fair value assumptions, Volatility rate	25.80%
Share-based compensation arrangement by share-based payment award, options expiry date	Jul. 22, 2024
President and Chief Operating Officer [Member] | Incentive Stock Options [Member] | Range One [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of stock option equity instruments granted during the period	35,678
Weighted-average fair value each option granted	$ 272.88
Percentage of fair market value of the common stock on the grant date	125.00%
President and Chief Operating Officer [Member] | Incentive Stock Options [Member] | Range Two [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of stock option equity instruments granted during the period	41,189
Weighted-average fair value each option granted	$ 294.71
Percentage of fair market value of the common stock on the grant date	135.00%

Earnings Per Share - Basic and

Earnings Per Share - Basic and Diluted Weighted Average Shares Outstanding Used to Compute Earnings Per Share (Detail) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Earnings Per Share Basic And Diluted [Abstract]
Basic weighted average shares outstanding	37,066	36,951	37,053	36,952
Dilutive effect of stock options and restricted stock	929	877	860	907
Diluted weighted average shares outstanding	37,995	37,828	37,913	37,859

Earnings Per Share - Additional

Earnings Per Share - Additional Information (Detail) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Stock Options and Restricted Stock [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Stock options and restricted stock excluded from the computation of diluted earnings per share	5,646	28,760	194,672	42,159

Credit Agreement - Additional I

Credit Agreement - Additional Information (Detail) - USD ($)	1 Months Ended				9 Months Ended
	Oct. 31, 2019	Oct. 31, 2018	Oct. 31, 2017	Oct. 31, 2015	Sep. 30, 2019
Line Of Credit Facility [Line Items]
Revolving loans and letters of credit				$ 100,000,000
Letter of credit outstanding					$ 1,000,000
Additional Credit Agreement				$ 50,000,000
Amount available under credit agreement					$ 99,000,000
Period of credit agreement				2 years
Equity interest					65.00%
Minimum [Member]
Line Of Credit Facility [Line Items]
Excess judgments against the company					$ 10,000,000
Credit Agreement [Member]
Line Of Credit Facility [Line Items]
Expiration period of credit agreement		Oct. 31, 2019	Oct. 31, 2018
Period of credit agreement			1 year
Credit Agreement [Member] | Scenario, Forecast [Member]
Line Of Credit Facility [Line Items]
Expiration period of credit agreement	Oct. 31, 2020

Leases - Additional Information

Leases - Additional Information (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2019USD ($)ft²Agreement
Lessee Lease Description [Line Items]
Operating lease, option to extend	Certain leases contain options to extend the initial term at the Company’s discretion
Operating lease, existence of option to extend [true false]	true
Weighted average remaining lease term	13 years 10 months 24 days
Weighted average discount rate	6.00%
Number of lease agreements assigned to third parties | Agreement	2
Future lease obligation under sublease arrangements	$ 4,600
Area of square feet for office space | ft²	15,646
Lease commencement date	Dec. 1, 2019
Lease expiration date	Jan. 15, 2027
Aggregate minimum rental commitment amount	$ 7,800
Operating lease right-of-use assets	75,390
Operating lease liabilities	92,031
Office Space [Member]
Lessee Lease Description [Line Items]
Operating lease right-of-use assets	6,700
Operating lease liabilities	$ 6,700
Property One [Member]
Lessee Lease Description [Line Items]
Lease termination dates	2020-11
Property Two [Member]
Lessee Lease Description [Line Items]
Lease termination dates	2022-02
Minimum [Member]
Lessee Lease Description [Line Items]
Term of lease contract	1 year
Maximum [Member]
Lessee Lease Description [Line Items]
Term of lease contract	15 years

Leases - Schedule of Components

Leases - Schedule of Components of Occupancy Expense (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019
Lease Cost [Line Items]
Net lease cost	$ 2,611	$ 8,167
Other, net [Member]
Lease Cost [Line Items]
Operating lease cost for subleased/assigned properties	707	1,863
Sublease income subleased/assigned properties	(707)	(1,863)
Occupancy [Member]
Lease Cost [Line Items]
Operating lease cost	2,602	8,003
Variable lease costs	$ 9	$ 164

Leases - Schedule of Maturity o

Leases - Schedule of Maturity of Lease Liabilities (Detail) $ in Thousands	Sep. 30, 2019USD ($)
Leases [Abstract]
Remainder of 2019	$ 2,412
2020	11,238
2021	10,245
2022	9,032
2023	8,703
2024 and thereafter	96,105
Total lease payments	137,735
Less: interest	45,704
Present value of lease liabilities	$ 92,031

Leases - Summary of Minimum Lea

Leases - Summary of Minimum Lease Commitments (Detail) $ in Thousands	Dec. 31, 2018USD ($)
Operating Leases Future Minimum Payments Due [Abstract]
2019	$ 9,764
2020	10,919
2021	10,114
2022	9,067
2023	8,738
2024 and thereafter	95,467
Operating Leases	$ 144,069

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) $ in Millions	9 Months Ended
	Sep. 30, 2019USD ($)Subsidiary	Sep. 30, 2018USD ($)
Commitments And Contingencies Disclosure [Abstract]
Number of subsidiaries | Subsidiary	2
Settlement days of bond transaction	Within one to two trading days
Collateral deposits | $	$ 1.1	$ 1.2

Share Repurchase Program - Addi

Share Repurchase Program - Additional Information (Detail) - Share Repurchase Program [Member] - USD ($)	1 Months Ended		9 Months Ended
	Jan. 31, 2019	Sep. 30, 2017	Sep. 30, 2019
Equity Class Of Treasury Stock [Line Items]
Shares repurchase program period	2 years	15 months
Shares repurchase program authorized	$ 100,000,000	$ 100,000,000
Commencement date	2019-04	2017-10
Total shares repurchased			43,715
Cost of common stock shares repurchased			$ 11,400,000

Segment and Geographic Inform_3

Segment and Geographic Information - Additional Information (Detail) - Segment	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Revenues From External Customers And Long Lived Assets [Line Items]
Number of operating segment	1
Geographic Concentration Risk [Member] | Total Revenue and Long-lived Assets [Member] | United Kingdom [Member]
Revenues From External Customers And Long Lived Assets [Line Items]
Concentration Risk, Percentage	10.00%	10.00%

Segment and Geographic Inform_4

Segment and Geographic Information - Summary of Revenue and Long-lived Assets (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Segment Reporting Information [Line Items]
Revenues	$ 131,597	$ 101,443	$ 381,578	$ 323,121
Long-lived assets	66,531		66,531		$ 63,010
United States [Member]
Segment Reporting Information [Line Items]
Revenues	109,526	85,110	317,282	271,833
Long-lived assets	59,146		59,146		55,200
United Kingdom [Member]
Segment Reporting Information [Line Items]
Revenues	21,417	15,882	62,390	49,828
Long-lived assets	7,355		7,355		7,787
Other [Member]
Segment Reporting Information [Line Items]
Revenues	654	$ 451	1,906	$ 1,460
Long-lived assets	$ 30		$ 30		$ 23

Acquisition - Additional Inform

Acquisition - Additional Information (Detail) - Liquity Edge, LLC [Member] $ in Millions	Aug. 12, 2019USD ($)
Business Acquisition [Line Items]
Aggregate purchase price	$ 150
Aggregate in cash	100
Business combination, common stock value	$ 50