MarketAxess (MKTX) 10-K 24 Feb 14 2013 FY Annual report Financial data

Document_and_Entity_Informatio

Document and Entity Information (USD $)	12 Months Ended
In Billions, except Share data, unless otherwise specified	Dec. 31, 2013	Feb. 21, 2014	Jun. 28, 2013
Document And Entity Information [Abstract]	'	'	'
Document Type	'10-K	'	'
Amendment Flag	'false	'	'
Document Period End Date	31-Dec-13	'	'
Document Fiscal Year Focus	'2013	'	'
Document Fiscal Period Focus	'FY	'	'
Entity Registrant Name	'MARKETAXESS HOLDINGS INC	'	'
Entity Central Index Key	'0001278021	'	'
Current Fiscal Year End Date	'--12-31	'	'
Entity Well-known Seasoned Issuer	'Yes	'	'
Entity Current Reporting Status	'Yes	'	'
Entity Voluntary Filers	'No	'	'
Entity Filer Category	'Large Accelerated Filer	'	'
Entity Common Stock, Shares Outstanding	'	37,790,658	'
Entity Public Float	'	'	$1.70

Consolidated_Statements_of_Fin

Consolidated Statements of Financial Condition (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
ASSETS	'	'
Cash and cash equivalents	$132,691	$128,908
Securities available-for-sale, at fair value	67,742	51,208
Accounts receivable, net of allowance of $133 and $75 as of December 31, 2013 and December 31, 2012, respectively	34,158	31,044
Goodwill and intangible assets, net of accumulated amortization	68,697	33,134
Furniture, equipment, leasehold improvements and capitalized software, net of accumulated depreciation and amortization	32,703	18,009
Prepaid expenses and other assets	10,640	8,096
Deferred tax assets, net	4,947	9,442
Total assets	351,578	279,841
Liabilities	'	'
Accrued employee compensation	23,811	19,916
Deferred revenue	2,713	4,864
Accounts payable, accrued expenses and other liabilities	14,692	12,344
Total liabilities	41,216	37,124
Commitments and Contingencies (Note 13)	'	'
Stockholders' equity	'	'
Preferred stock	'	'
Additional paid-in capital	295,557	283,609
Treasury stock-Common stock voting, at cost, 1,495,159 shares as of December 31, 2013 and December 31, 2012	-32,273	-32,273
Retained earnings (deficit)	51,042	-5,644
Accumulated other comprehensive loss	-4,083	-3,093
Total stockholders' equity	310,362	242,717
Total liabilities and stockholders' equity	351,578	279,841
Common Stock Voting [Member]	'	'
Stockholders' equity	'	'
Common stock	119	118
Total stockholders' equity	119	118
Series A Preferred Stock [Member]	'	'
Stockholders' equity	'	'
Preferred stock	'	'
Common Stock Non-Voting [Member]	'	'
Stockholders' equity	'	'
Common stock	'	'

Consolidated_Statements_of_Fin1

Consolidated Statements of Financial Condition (Parenthetical) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, except Share data, unless otherwise specified
Allowance for accounts receivable	$133	$75
Preferred stock, par value	$0.00	$0.00
Preferred stock, shares authorized	4,855,000	4,855,000
Preferred stock, shares issued	'	'
Preferred stock, shares outstanding	'	'
Treasury stock, shares	1,495,159	1,495,159
Series A Preferred Stock [Member]	'	'
Preferred stock, par value	$0.00	$0.00
Preferred stock, shares authorized	110,000	110,000
Preferred stock, shares issued	'	'
Preferred stock, shares outstanding	'	'
Common Stock Non-Voting [Member]	'	'
Common stock, par value	$0.00	$0.00
Common stock, shares authorized	10,000,000	10,000,000
Common stock, shares issued	'	'
Common stock, shares outstanding	'	'
Common Stock Voting [Member]	'	'
Common stock, par value	$0.00	$0.00
Common stock, shares authorized	110,000,000	110,000,000
Common stock, shares issued	39,224,016	38,902,294
Common stock, shares outstanding	37,728,857	37,407,135

Consolidated_Statements_of_Ope

Consolidated Statements of Operations (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Revenues	'	'	'
Commissions	$203,652	$174,199	$155,444
Information and post-trade services	25,377	7,435	7,199
Technology products and services	6,331	4,988	5,085
Investment income	420	1,057	1,228
Other	2,953	3,161	2,918
Total revenues	238,733	190,840	171,874
Expenses	'	'	'
Employee compensation and benefits	64,406	54,678	52,443
Depreciation and amortization	14,123	6,758	5,206
Technology and communications	16,037	12,523	10,619
Professional and consulting fees	18,220	12,150	9,006
Occupancy	5,173	2,446	2,337
Marketing and advertising	4,632	5,169	4,491
General and administrative	8,862	7,746	6,322
Total expenses	131,453	101,470	90,424
Income before income taxes from continuing operations	107,280	89,370	81,450
Provision for income taxes	38,717	27,586	32,003
Net income from continuing operations	68,563	61,784	49,447
(Loss) from discontinued operations, net of income taxes	-189	-1,715	-1,743
Gain on the sale of discontinued operations, net of tax benefit	7,642	'	'
Net income	$76,016	$60,069	$47,704
Basic earnings per common share	'	'	'
Income from continuing operations	$1.86	$1.69	$1.34
Income (loss) from discontinued operations	$0.20	($0.04)	($0.05)
Net income per common share	$2.06	$1.65	$1.29
Diluted earnings per common share	'	'	'
Income from continuing operations	$1.81	$1.64	$1.25
Income (loss) from discontinued operations	$0.20	($0.05)	($0.05)
Net income per common share	$2.01	$1.59	$1.20
Cash dividends declared per common share	$0.52	$1.74	$0.36
Weighted average shares outstanding	'	'	'
Basic	36,886	36,516	37,006
Diluted	37,888	37,816	39,608

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Statement Of Income And Comprehensive Income [Abstract]	'	'	'
Net income	$76,016	$60,069	$47,704
Net cumulative translation adjustment and foreign currency exchange hedge, net of tax of $(310), $(390) and $(440), respectively	-537	-748	-634
Net unrealized gain (loss) on securities available-for-sale, net of tax of $14, $(244), and $271, respectively	21	-342	403
Less: reclassification adjustment for realized gain on the sale of securities available-for-sale included in Other Income, net of tax of $(299), $(76) and $0, respectively	-474	-121	'
Net changed in unrealized (loss) gain on securities available-for-sale, net of tax	-453	-463	403
Comprehensive Income	$75,026	$58,858	$47,473

Consolidated_Statements_of_Com1

Consolidated Statements of Comprehensive Income (Parenthetical) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Statement Of Income And Comprehensive Income [Abstract]	'	'	'
Foreign currency exchange hedge, net of tax	($310)	($390)	($440)
Securities available-for-sale, net of tax	14	-244	271
Other Income, net of tax	($299)	($76)	$0

Consolidated_Statements_of_Cha

Consolidated Statements of Changes in Stockholders' Equity (USD $)	Total	Common Stock Voting [Member]	Additional Paid-in Capital [Member]	Treasury Stock - Common Stock Voting [Member]	Retained Earnings (Deficit) [Member]	Accumulated Other Comprehensive Loss [Member]	Common Stock Non-Voting [Member]
In Thousands
Beginning Balance at Dec. 31, 2010	$234,476	$108	$340,615	($70,000)	($34,605)	($1,651)	$9
Net income	47,704	'	'	'	47,704	'	'
Cumulative translation adjustment and foreign currency exchange hedge, net of tax	-634	'	'	'	'	-634	'
Unrealized net gain (loss) on securities available-for-sale, net of tax	403	'	'	'	'	403	'
Stock-based compensation	6,859	'	6,859	'	'	'	'
Exercise of stock options	6,807	4	6,803	'	'	'	'
Withholding tax payments on restricted stock vesting and stock option exercises	-4,415	'	-4,415	'	'	'	'
Conversion of Series B Preferred stock to common stock voting	30,315	1	-20,688	51,002	'	'	'
Tax benefit from the exercise of warrants in prior years	4,237	'	4,237	'	'	'	'
Excess tax benefits from stock-based compensation	7,305	'	7,305	'	'	'	'
Repurchases of common stock	-6,935	'	'	-6,935	'	'	'
Cash dividend on common stock	-13,683	'	'	'	-13,683	'	'
Ending Balance at Dec. 31, 2011	312,439	113	340,716	-25,933	-584	-1,882	9
Net income	60,069	'	'	'	60,069	'	'
Cumulative translation adjustment and foreign currency exchange hedge, net of tax	-748	'	'	'	'	-748	'
Unrealized net gain (loss) on securities available-for-sale, net of tax	-463	'	'	'	'	-463	'
Stock-based compensation	8,385	'	8,385	'	'	'	'
Exercise of stock options	8,525	3	8,522	'	'	'	'
Withholding tax payments on restricted stock vesting and stock option exercises	-20,003	'	-20,003	'	'	'	'
Excess tax benefits from stock-based compensation	14,775	'	14,775	'	'	'	'
Conversion of common stock non-voting to common stock voting	'	2	-15,878	15,878	'	'	-2
Repurchases of common stock	-75,133	'	-52,908	-22,218	'	'	-7
Cash dividend on common stock	-65,129	'	'	'	-65,129	'	'
Ending Balance at Dec. 31, 2012	242,717	118	283,609	-32,273	-5,644	-3,093	'
Net income	76,016	'	'	'	76,016	'	'
Cumulative translation adjustment and foreign currency exchange hedge, net of tax	-537	'	'	'	'	-537	'
Unrealized net gain (loss) on securities available-for-sale, net of tax	-453	'	'	'	'	-453	'
Stock-based compensation	8,879	'	8,879	'	'	'	'
Exercise of stock options	3,039	1	3,038	'	'	'	'
Withholding tax payments on restricted stock vesting and stock option exercises	-5,001	'	-5,001	'	'	'	'
Excess tax benefits from stock-based compensation	5,032	'	5,032	'	'	'	'
Cash dividend on common stock	-19,330	'	'	'	-19,330	'	'
Ending Balance at Dec. 31, 2013	$310,362	$119	$295,557	($32,273)	$51,042	($4,083)	'

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash flows from operating activities	'	'	'
Net income	$76,016	$60,069	$47,704
Adjustments to reconcile net income to net cash provided by operating activities:	'	'	'
Depreciation and amortization	13,051	8,233	6,781
Stock-based compensation expense	8,879	8,385	6,859
Deferred taxes	1,001	-643	16,129
Gain on the sale of discontinued operations	-7,642	'	'
Other	-296	1,204	1,177
Changes in operating assets and liabilities:	'	'	'
(Increase) decrease in accounts receivable	-1,714	4,607	-11,665
(Increase) decrease in prepaid expenses and other assets	-1,846	412	-4,074
Increase in accrued employee compensation	3,820	491	1,634
(Decrease) increase in deferred revenue	-1,571	-462	755
Increase (decrease) in accounts payable, accrued expenses and other liabilities	1,181	-714	178
Net cash provided by operating activities	90,879	81,582	65,478
Cash flows from investing activities	'	'	'
Acquisition of business, net of cash acquired	-37,827	'	'
Cash proceeds from the sale of discontinued operations, net of cash sold	9,346	'	'
Securities available-for-sale:	'	'	'
Proceeds from sales	30,900	23,663	'
Proceeds from maturities	12,515	18,313	27,419
Purchases	-60,755	-16,543	-32,302
(Increase) decrease in securities and cash provided as collateral	-18	-43	3,532
Purchases of furniture, equipment and leasehold improvements	-15,337	-5,153	-3,160
Capitalization of software development costs	-7,945	-5,207	-4,065
Net cash (used in ) provided by investing activities	-69,121	15,030	-8,576
Cash flows from financing activities	'	'	'
Cash dividend on common stock	-19,837	-64,041	-13,683
Exercise of stock options	3,039	8,525	6,807
Withholding tax payments on restricted stock vesting and stock option exercises	-5,001	-20,003	-4,415
Excess tax benefits from stock-based compensation	5,032	14,775	7,305
Repurchase of common stock	'	-75,133	-6,935
Other	-307	-298	-278
Net cash (used in) financing activities	-17,074	-136,175	-11,199
Effect of exchange rate changes on cash and cash equivalents	-901	-1,149	-1,077
Cash and cash equivalents	'	'	'
Net increase (decrease) for the period	3,783	-40,712	44,626
Beginning of period	128,908	169,620	124,994
End of period	132,691	128,908	169,620
Cash paid during the year	'	'	'
Cash paid for income taxes	30,768	15,102	10,177
Non-cash investing and financing activity:	'	'	'
Conversion of Series B Preferred Stock to common stock	'	'	30,315
Conversion of common stock non-voting to common stock voting	'	15,880	'
Liabilities assumed in connection with the Xtrakter acquisition:	'	'	'
Fair value of assets acquired	44,791	'	'
Cash paid for the capital stock	-37,827	'	'
Liabilities assumed	$6,964	'	'

Organization_and_Principal_Bus

Organization and Principal Business Activity	12 Months Ended
	Dec. 31, 2013
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. Through its subsidiaries, the Company operates an electronic trading platform for corporate bonds and other types of fixed-income instruments through which the Company’s institutional investor clients can access liquidity provided by its broker-dealer clients. The Company’s multi-dealer trading platform allows its institutional investor clients to simultaneously request competitive, executable bids or offers from multiple broker-dealers, and to execute trades with the broker-dealer of their choice. The Company’s trading platform provides access to global liquidity in U.S. high-grade corporate bonds, emerging markets and high-yield bonds, European bonds, U.S. agency bonds, credit default swaps and other fixed-income securities. The Company also executes certain bond transactions between and among institutional investor and broker-dealer clients on a riskless principal basis by serving as counterparty to both the buyer and the seller in trades which then settle through a third-party clearing organization. The Company provides fixed-income market data analytics and compliance tools that help its clients make trading decisions. The Company also provides trade matching and regulatory transaction reporting services to the securities markets. In addition, the Company provides technology solutions and professional consulting services to fixed-income industry participants.

Significant_Accounting_Policie

Significant Accounting Policies	12 Months Ended
	Dec. 31, 2013
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.
	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. The Company defines cash equivalents as short-term interest-bearing investments with maturities at the time of purchase of three months or less.
	Securities Available-for-Sale
	The Company classifies its marketable securities as available-for-sale securities. Unrealized marketable securities gains and losses, net of taxes, are reflected as a net amount under the caption of accumulated other comprehensive loss on the Consolidated Statements of Financial Condition. Realized gains and losses are recorded in the Consolidated Statements of Operations in other revenues. For the purpose of computing realized gains and losses, cost is determined on a specific identification basis.
	The Company assesses whether an other-than-temporary impairment loss on the 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 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 2013, 2012 or 2011.
	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 portfolio and one foreign currency forward contract. All other financial instruments are short-term in nature and the carrying amount reported on our Consolidated Statements of Financial Condition 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.
	The allowance for doubtful accounts was $0.1 million, $0.1 million and $1.1 million as of December 31, 2013, 2012 and 2011, respectively. The provision for bad debts was $0.2 million, $0.2 million and $1.1 million for the years ended December 31, 2013, 2012 and 2011, respectively. During the fourth quarter of 2011, MF Global Inc., a broker-dealer market maker on the Company’s platform, entered a liquidation proceeding. In connection with the proceeding, the Company recorded a 100% allowance against outstanding receivables amounting to $0.9 million. Write-offs and other charges against the allowance for doubtful accounts were $0.1 million, $1.4 million and $0.2 million for the years ended December 31, 2013, 2012 and 2011, respectively.
	Depreciation and Amortization
	Fixed assets are carried at cost less accumulated depreciation. The Company depreciates computer hardware and related software, office hardware and furniture and fixtures on a straight-line basis 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.
	Cash Provided as Collateral
	Cash is provided as collateral for electronic bank settlements and broker-dealer clearance 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 general and administrative expense 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 majority of the Company’s revenues are derived from commissions for trades executed on its platform and distribution fees that are billed to its broker-dealer clients on a monthly basis. The Company also derives revenues from information and post-trade services, technology products and services, investment income and other income.
	Commission revenue. Commissions are generally calculated as a percentage of the notional dollar volume of bonds traded on the platform and vary based on the type and maturity of the bond traded. Under the Company’s 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. For trades that the Company executes between and among institutional investor and broker-dealer clients on a riskless principal basis by serving as counterparty to both the buyer and the seller, the Company earns the commission through the difference in price between the two riskless principal trades. Fee programs for certain products include distribution fees which are recognized monthly.
	Information and post-trade services. The Company generates revenue from information services provided to its broker-dealer clients, institutional investor clients and data-only subscribers. Information services are invoiced monthly, quarterly or annually. When billed in advance, revenues are recognized monthly on a straight-line basis. The Company also generates revenue from trade matching and regulatory transaction reporting services. Revenue is recognized in the period the services are provided.
	Technology products and services. The Company generates revenues from technology software licenses, maintenance and support services (referred to as post-contract technical support or “PCS”) and professional consulting services. Revenue is generally recognized when persuasive evidence of an arrangement exists, delivery has occurred, the fee is fixed or determinable and collection is considered probable. The Company generally sells software licenses and PCS together as part of multiple-element arrangements. The Company also enters into contracts for technology integration consulting services unrelated to any software product.
	For arrangements that include multiple elements, generally software licenses and PCS, the Company allocates and defers revenue for the undelivered items based on vendor specific objective evidence (“VSOE”) of the fair value of the undelivered elements and recognizes the difference between the total arrangement fee and the amount deferred for the undelivered items as license revenue. The Company’s VSOE of each element is based on historical evidence of stand-alone sales of these elements to third parties or the stated renewal rate for the undelivered elements. When VSOE does not exist for undelivered items, the entire arrangement fee is recognized ratably over the performance period. For PCS, the term is typically one year and revenue is recognized over the duration of the arrangement on a straight-line basis.
	Professional consulting services are generally separately priced and are typically not essential to the functionality of the Company’s software products. Revenues from these services are recognized separately from the license fee. Generally, revenue from time-and-materials consulting contracts is recognized as services are performed.
	Revenues from contracts for technology integration consulting services are recognized on the percentage-of-completion method. Percentage-of-completion accounting involves calculating the percentage of services provided during the reporting period compared to the total estimated services to be provided over the duration of the contract. If estimates indicate that a contract loss will occur, a loss provision is recorded in the period in which the loss first becomes probable and reasonably estimable. Contract losses are determined to be the amount by which the estimated direct and indirect costs of the contract exceed the estimated total revenues that will be generated by the contract. There were no contract loss provisions recorded as of December 31, 2013, 2012 and 2011. Revenues recognized in excess of billings are recorded as unbilled services within other assets. Billings in excess of revenues recognized are recorded as deferred revenues until revenue recognition criteria are met.
	Initial set-up fees. The Company enters into agreements with its broker-dealer clients pursuant to which the Company provides access to its platform through a non-exclusive and non-transferable license. Broker-dealer clients may pay an initial set-up fee, which is typically due and payable upon execution of the broker-dealer agreement. The initial set-up fee, if any, varies by agreement. Revenue is recognized over the initial term of the agreement, which is generally two years. Initial set-up fees are reported in other income in the Consolidated Statements of Operations.
	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.
	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.
	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 is judgmental in nature 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 U.S. generally accepted accounting principles 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.
	Out-of-Period Adjustment
	During the second quarter of 2013, the Company determined that it had incorrectly excluded incentive compensation as a component of employee compensation eligible for capitalization under its software development costs capitalization policy. The Company assessed this error and determined that it was not material to previous reporting periods and is not material to the current year. Therefore, the Company recorded this item as an out-of-period adjustment in the three months ended June 30, 2013 by reducing employee compensation and benefits expense by $2.9 million and increasing depreciation and amortization expense by $1.3 million in the Consolidated Statements of Operations and increasing the net book value of capitalized software by $1.6 million in the Consolidated Statements of Financial Condition. This item was reflected as a non-cash adjustment in the Consolidated Statements of Cash Flows.
	Recent Accounting Pronouncements
	In 2012, the Financial Accounting Standards Board issued new guidance related to the Statement of Comprehensive Income. Reclassification adjustments out of accumulated other comprehensive income are required on the face of the Consolidated Statement of Comprehensive Income. This accounting standard is effective for fiscal years beginning on or after December 15, 2012. The Company adopted the new guidance effective January 1, 2013.

Net_Capital_Requirements_and_C

Net Capital Requirements and Customer Protection Requirements	12 Months Ended
	Dec. 31, 2013
Text Block [Abstract]	'
Net Capital Requirements and Customer Protection Requirements	'
	3. Net Capital Requirements and Customer Protection Requirements
	MarketAxess Corporation, a U.S. subsidiary, is a registered broker-dealer with the Securities Exchange Commission ("SEC") and is a member of the Financial Industry Regulatory Authority (“FINRA”). MarketAxess Corporation claims exemption from SEC Rule 15c3-3, as it does not hold customer securities or funds on account, as defined. Pursuant to the Uniform Net Capital Rule under the Securities Exchange Act of 1934, MarketAxess Corporation is required to maintain minimum net capital, as defined, equal to the greater of $250,000 or 6 2/3% of aggregate indebtedness. MarketAxess Europe Limited, a U.K. subsidiary, is registered as a Multilateral Trading Facility dealer with the Financial Conduct Authority (formerly the Financial Services Authority) (“FCA”) in the U.K. MarketAxess Canada Company, a Canadian subsidiary, is registered as an Alternative Trading System dealer under the Securities Act of Ontario and is a member of the Investment Industry Regulatory Organization of Canada. MarketAxess Europe Limited and MarketAxess Canada Company are subject to certain financial resource requirements of the FCA and the Ontario Securities Commission, respectively. The following table sets forth the capital requirements, as defined, that the Company’s subsidiaries were required to maintain as of December 31, 2013:
		MarketAxess		MarketAxess		MarketAxess
		Corporation		Europe Limited		Canada Company
		(In thousands)
	Net capital	$	86,367	$	17,792	$	865
	Minimum net capital required		1,859		3,227		259
	Excess net capital	$	84,508	$	14,565	$	606
	The Company’s regulated subsidiaries are subject to U.S., U.K. and Canadian regulations which 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.
	In September 2013, the U.S. Commodity Futures Trading Commission (“CFTC”) granted temporary registration to MarketAxess SEF Corporation, a U.S. subsidiary of the Company, to operate a swap execution facility (the “SEF”) for the trading of swaps subject to the CFTC’s jurisdiction. The SEF, which commenced operations in October 2013, is subject to various CFTC regulations, including maintenance of a minimum level of financial resources, estimated to be approximately $6.0 million.

Fair_Value_Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2013
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 December 31, 2013
	Money market funds	$	90,536		$	—		$	—		$	90,536
	Securities available-for-sale
	Municipal securities		—			16,052			—			16,052
	Corporate bonds		—			51,690			—			51,690
	Foreign currency forward position		—			(472	)		—			(472	)
		$	90,536		$	67,270		$	—		$	157,806
	As of December 31, 2012
	Money market funds	$	83,519		$	—		$	—		$	83,519
	Securities available-for-sale
	U.S. government obligations		—			31,104			—			31,104
	Municipal securities		—			17,947			—			17,947
	Corporate bonds		—			2,157			—			2,157
	Foreign currency forward and option contracts		—			15			—			15
		$	83,519		$	51,223		$	—		$	134,742
	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. There were no financial assets classified within Level 3 during 2013 and 2012.
	The Company enters into foreign currency forward contracts to hedge the exposure to variability in certain foreign currency cash flows resulting from the net investment in the Company’s U.K. subsidiaries. The Company assesses each foreign currency forward contract to ensure that it is highly effective at reducing the exposure being hedged. The Company designates each foreign currency forward contract as a hedge, 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 liability is included in accounts payable 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 foreign currency forward contracts is as follows:
		As of December 31,
		2013			2012
		(In thousands)
	Notional value	$	29,431		$	15,792
	Fair value of notional		29,903			15,809
	Fair value of the liability	$	(472	)	$	(17	)
	The following is a summary of the Company’s securities available-for-sale:
					Gross			Gross			Estimated
		Amortized			unrealized			unrealized			fair
		cost			gains			losses			value
		(In thousands)
	As of December 31, 2013
	Municipal securities	$	16,049		$	9		$	(6	)	$	16,052
	Corporate bonds		51,579			124			(13	)		51,690
	Total securities available-for-sale	$	67,628		$	133		$	(19	)	$	67,742
	As of December 31, 2012
	U.S. government obligations	$	30,255		$	849		$	—		$	31,104
	Municipal securities		17,941			10			(4	)		17,947
	Corporate bonds		2,159			—			(2	)		2,157
	Total securities available-for-sale	$	50,355		$	859		$	(6	)	$	51,208
	The following table summarizes the contractual maturities of securities available-for-sale:
		As of December 31,
		2013			2012
		(In thousands)
	Less than one year	$	12,332		$	10,870
	Due in 1—5 years		55,410			40,338
	Total securities available-for-sale	$	67,742		$	51,208
	Proceeds from the sales and maturities of securities available-for-sale during 2013, 2012 and 2011 were $43.4 million, $42.0 million and $27.4 million, respectively.
	The following table provides fair values and unrealized losses on securities available-for-sale and by the aging of the securities’ continuous unrealized loss position:
		Less than Twelve Months						Twelve Months or More						Total
		Estimated			Gross			Estimated			Gross			Estimated		Gross
		fair			unrealized			fair			unrealized			fair		unrealized
		value			losses			value			losses			value		losses
		(In thousands)
	As of December 31, 2013
	Municipal securities	$	4,955		$	(6	)	$	—		$	—		$	4,955	$	(6	)
	Corporate bonds		10,728			(13	)		—			—			10,728		(13	)
	Total	$	15,683		$	(19	)	$	—		$	—		$	15,683	$	(19	)
	As of December 31, 2012
	U.S. government obligations	$	—		$	—		$	—		$	—		$	—	$	—
	Municipal securities		2,780			(4	)		—			—			2,780		(4	)
Corporate bonds		2,157			(2	)		—			—			2,157		(2	)
Total	$	4,937		$	(6	)	$	—		$	—		$	4,937	$	(6	)

Acquisition

Acquisition	12 Months Ended
	Dec. 31, 2013
Business Combinations [Abstract]	'
Acquisition	'
	5. Acquisition
	In February 2013, the Company acquired all of the outstanding shares of Xtrakter Limited (“Xtrakter”) from Euroclear S.A./N.V. Xtrakter is a U.K.-based provider of trade matching and regulatory transaction reporting for European securities and market and reference data across a range of fixed-income products. The acquisition of Xtrakter provides the Company with an expanded set of technology solutions ahead of incoming pre-and post-trade transparency mandates from the Markets in Financial Instruments Directive II in Europe. The aggregate purchase price was $37.8 million in cash, net of acquired cash. During the year ended December 31, 2013, transaction costs including legal, regulatory, accounting, tax, valuation and other professional services were $1.6 million.
	The Company has completed its allocation of the purchase price to the fair value of assets acquired and liabilities assumed at the date of acquisition. The purchase price allocation is as follows (in thousands):
	Purchase price	$	46,683
	Less: acquired cash		(8,856	)
	Purchase price, net of acquired cash		37,827
	Accounts receivable		3,733
	Intangible assets		13,255
	Other assets		1,718
	Deferred tax liability, net		(2,342	)
	Accounts payable, accrued expenses and deferred revenue		(4,622	)
	Goodwill	$	26,085
	The acquired intangible assets are as follows (in thousands, except for useful lives):
		Costs			Useful Lives
	Customer relationships	$	5,455			10-15 years
	Internally developed software		5,000			3 years
	Tradename- indefinite life		1,820			indefinite
	Tradename- finite life		300			3 years
	Non-compete agreement		380			3 years
	Other		300			indefinite
	Total	$	13,255
	The identifiable intangible assets and goodwill are not deductible for tax purposes.
	Since the date of the acquisition, Xtrakter-related revenue and net loss of $18.4 million and $0.9 million, respectively, have been included in the Company’s Consolidated Statements of Operations. The following unaudited pro forma consolidated financial information reflects the results of continuing operations of the Company for the years ended December 31, 2013, 2012 and 2011, as if the acquisition of Xtrakter had occurred as of the beginning of each period presented, after giving effect to certain purchase accounting adjustments. These pro forma results are not necessarily indicative of what the Company’s operating results would have been had the acquisition actually taken place at the beginning of each period presented. The pro forma financial information includes the amortization charges from acquired intangible assets, adjustments to interest income to reflect the cash purchase price and related tax effects.
		Pro forma
		Year Ended December 31,
		2013			2012		2011
		(In thousands, except per share amounts)
	Revenues	$	242,657		$	214,683	$	195,741
	Income before income taxes	$	107,316		$	88,361	$	82,769
	Net income	$	68,579		$	61,210	$	50,560
	Basic net income per common share	$	1.86		$	1.68	$	1.37
	Diluted net income per common share	$	1.81		$	1.62	$	1.28

Goodwill_and_Intangible_Assets

Goodwill and Intangible Assets	12 Months Ended
	Dec. 31, 2013
Goodwill And Intangible Assets Disclosure [Abstract]	'
Goodwill and Intangible Assets	'
	6. Goodwill and Intangible Assets
	The following is a summary of changes in goodwill and intangible assets with indefinite lives for the year ended December 31, 2013 (in thousands):
	Balance at beginning of period	$	31,785
	Goodwill from Xtrakter acquisition		26,085
	Intangible assets with indefinite lives from Xtrakter acquisition		2,120
	Less: Goodwill ascribed to discontinued operations		(277	)
	Balance at end of period	$	59,713
	Intangible assets that are subject to amortization, including the related accumulated amortization, are comprised of the following:
		December 31, 2013								December 31, 2012
		Cost			Accumulated			Net		Cost		Accumulated			Net
					Amortization			Carrying				Amortization			Carrying
								Amount							Amount
		(In thousands)
	Technology	$	5,770		$	(2,159	)	$	3,611	$	4,010	$	(3,892	)	$	118
	Customer relationships		5,698			(816	)		4,882		3,530		(2,364	)		1,166
	Non-competition agreements		380			(106	)		274		1,260		(1,214	)		46
	Tradenames		370			(153	)		217		590		(570	)		20
	Total	$	12,218		$	(3,234	)	$	8,984	$	9,390	$	(8,040	)	$	1,350
	Amortization expense associated with identifiable intangible assets was $2.2 million and $42 thousand, respectively, for the years ended December 31, 2013 and 2012. Estimated total amortization expense is $2.3 million for 2014 and 2015, $0.7 million for 2016 and $0.4 million for 2017 and 2018.

Capitalized_Software_Furniture

Capitalized Software, Furniture, Equipment and Leasehold Improvements	12 Months Ended
	Dec. 31, 2013
Property Plant And Equipment [Abstract]	'
Capitalized Software, Furniture, Equipment and Leasehold Improvements	'
	7. Capitalized Software, Furniture, Equipment and Leasehold Improvements
	Capitalized software development costs, furniture, equipment and leasehold improvements, net of accumulated depreciation and amortization, are comprised of the following:
		As of December 31,
		2013			2012
		(In thousands)
	Software development costs	$	41,062		$	30,482
	Computer hardware and related software		22,051			15,702
	Office hardware		2,380			2,125
	Furniture and fixtures		1,777			1,479
	Leasehold improvements		8,129			4,709
	Computer hardware under capital lease		1,419			1,419
	Accumulated depreciation and amortization		(44,115	)		(37,907	)
	Total capitalized software, furniture, equipment and leasehold improvements, net of accumulated depreciation and amortization	$	32,703		$	18,009
	During the years ended December 31, 2013, 2012 and 2011, software development costs totaling $10.9 million, which includes the $2.9 million from the out-of-period adjustment, $5.2 million and $4.1 million, respectively, were capitalized. Non-capitalized software costs and routine maintenance costs are expensed as incurred and are included in employee compensation and benefits and professional and consulting fees in the Consolidated Statements of Operations.

Income_Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2013
Income Tax Disclosure [Abstract]	'
Income Taxes	'
	8. Income Taxes
	The provision for income taxes from continuing operations consists of the following:
		Year Ended December 31,
		2013			2012			2011
		(In thousands)
	Current:
	Federal	$	26,071		$	14,402		$	6,187
	State and local		5,958			2,287			2,849
	Foreign		1,014			1,315			1,194
	Total current provision		33,043			18,004			10,230
	Deferred:
	Federal		5,507			8,542			19,090
	State and local		812			1,046			2,667
	Foreign		(645	)		(6	)		16
	Total deferred provision		5,674			9,582			21,773
	Provision for income taxes	$	38,717		$	27,586		$	32,003
	Pre-tax income from U.S. operations was $105.2 million, $84.7 million and $77.1 million for the years ended December 31, 2013, 2012 and 2011, respectively. Pre-tax income from foreign operations was $2.1 million, $4.6 million and $4.4 million for the years ended December 31, 2013, 2012 and 2011, respectively.
	The difference between the Company’s reported provision for income taxes and the U.S. federal statutory rate of 35% is as follows:
		Year Ended December 31,
		2013			2012			2011
	U.S. federal tax at statutory rate		35	%		35	%		35	%
	State and local taxes—net of federal benefit		4.1			2.4			4.9
	Release of previously unrecognized tax benefits		—			(7.5	)		—
	Other, net		(3.0	)		1			(0.6	)
	Provision for income taxes		36.1	%		30.9	%		39.3	%
	The following is a summary of the Company’s net deferred tax assets:
		As of December 31,
		2013			2012
		(In thousands)
	Deferred tax assets
	U.S. net operating loss carryforwards	$	4,273		$	7,175
	Foreign net operating loss carryforwards		101			160
	Capital loss carryforwards		7,487			—
	Stock compensation expense		6,022			5,296
	Other		3,206			2,839
	Total deferred tax assets		21,089			15,470
	Valuation allowance		(7,743	)		(727	)
	Net deferred tax assets		13,346			14,743
	Deferred tax liabilities
	Depreciation and amortization		(1,905	)		(2,025	)
	Capitalized software development costs		(4,163	)		(2,752	)
	Intangible assets		(2,331	)		(524	)
	Deferred tax assets, net	$	4,947		$	9,442
	As of December 31, 2013, the Company had deferred tax assets associated with stock-based compensation of approximately $6.0 million. There is a risk that the ultimate tax benefit realized upon the exercise of stock options or vesting of restricted stock could be less than the tax benefit previously recognized and exhaust the additional-paid-in-capital pool. If this should occur, any excess tax benefit previously recognized would be reversed, resulting in an increase in tax expense. Since the tax benefit to be realized in the future is unknown, it is not currently possible to estimate the impact on the deferred tax balance. As of December 31, 2013, the additional paid-in-capital pool, which is determined under a one pool approach for employee and non-employee awards, was approximately $48.4 million. The additional paid-in-capital pool is currently sufficient to absorb a complete write-off of the stock-based compensation deferred tax asset.
	In 2001 and 2000, MarketAxess Holdings Inc. and MarketAxess Corporation had an ownership change within the meaning of Section 382 of the Internal Revenue Code. As of December 31, 2013, the Company had restricted U.S. federal net operating loss carryforwards of approximately $9.3 million, which begin to expire in 2021. The Company’s net operating loss carryforwards may be subject to additional annual limitations if there is a 50% or greater change in the Company’s ownership, as determined over a rolling three-year period. In addition, the Company has $0.7 million of foreign loss carry forwards which begin to expire in 2025.
	The Company issued warrants to certain broker-dealer stockholders at the time that they made an equity investment in the Company. All of the warrants were exercised prior to 2008. Through December 31, 2009, the tax benefit on a portion of the tax deduction generated on the exercise of the warrants had not yet been recorded. During 2010, the Company recognized a portion of the tax benefits amounting to $11.4 million as an increase to additional paid-in-capital due to the utilization of the related tax loss carryforwards of $31.0 million. During the first quarter of 2011, the Company recognized the remaining portion of the tax benefit, amounting to $4.2 million, as an increase to additional paid-in-capital due to the expected utilization of the related tax loss carryforwards of $10.4 million.
	The ultimate realization of deferred income tax assets is dependent upon the generation of future taxable income during the periods in which the temporary differences become deductible. If it is not more likely than not that some portion or all of the gross deferred income tax assets will be realized in future years, a valuation allowance is recorded. As of December 31, 2013, the valuation allowance relates to certain capital loss, foreign and state tax loss carryforwards that are not expected to be realized. The Company recognized a $20.6 million capital loss on the sale of Greenline Financial Technologies, Inc. (“Greenline”) (See Note 14, “Sale of Discontinued Operations”) of which $1.2 million was carried back or otherwise utilized against current period capital gains. A full valuation allowance was provided against the remaining capital loss carryforward.
	A summary of the changes in the valuation allowance follows:
		Year Ended December 31,
		2013			2012			2011
		(In thousands)
	Valuation allowance at beginning of year	$	727		$	287		$	249
	Increase (decrease) to valuation allowance attributable to:
	Current year income		(65	)		440			38
	State net operating loss		(406	)		—			—
	Capital loss		7,487			—			—
	Valuation allowance at end of year	$	7,743		$	727		$	287
	The Company or one of its subsidiaries files U.S. federal, state and foreign income tax returns. No income tax returns have been audited, with the exception of New York city (through 2003) and state (through 2006) and Connecticut state (through 2003) tax returns. An examination of the Company’s federal tax return for 2011 and New York state franchise tax returns for 2007 through 2009 is currently underway. The Company cannot estimate when the examinations will conclude.
	In the fourth quarter of 2012, the Company recorded a reduction to the income tax provision of $6.7 million. The Company updated the recognition of certain acquired net operating loss carryforwards in response to a private letter ruling received from the Internal Revenue Service. As a result, the reserve for unrecognized tax benefits amounting to $3.6 million was reversed and deferred tax assets were increased by $3.1 million to recognize additional tax loss carryforwards. A reconciliation of the unrecognized tax benefits is as follows:
		Year Ended December 31,
		2013			2012			2011
		(In thousands)
	Balance at beginning of year	$	49		$	3,647		$	3,329
Additions for tax positions of prior years		—			—			366
Additions for tax positions of current year		235			—			—
Reductions for tax positions of prior years		(19	)		(3,598	)		(48	)
Balance at end of year	$	265		$	49		$	3,647
Effective January 1, 2013, the Company has determined that unremitted earnings of its foreign subsidiaries will be considered indefinitely reinvested outside of the United States. There were no aggregate unremitted earnings as of December 31, 2012 and 2013.

Stockholders_Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2013
Equity [Abstract]	'
Stockholders' Equity	'
	9. Stockholders’ Equity
	Common Stock
	As of December 31, 2013 and 2012, the Company had 110,000,000 authorized shares of common stock and 10,000,000 authorized shares of non-voting common stock. Common stock entitles the holder to one vote per share of common stock held.
	In October 2011, the Board of Directors of the Company authorized a share repurchase program for up to $35.0 million of the Company’s common stock. A total of 955,342 shares were repurchased at an aggregate cost of $29.2 million. The share repurchase program expired on January 1, 2014. Shares repurchased under the program are held in treasury for future use.
	In February 2012, the Company repurchased 1,821,730 shares of the Company’s non-voting common stock from JPMorgan Chase & Co. (“JPM”) (See Note 15, “Related Party”) at a cost of $52.9 million. Shares repurchased from JPM were cancelled by the Company. JPM also converted 763,924 shares of non-voting common stock to voting common stock in February 2012.
	In January 2014, the Board of Directors of the Company authorized a share repurchase program for up to $35.0 million of the Company’s common stock. Shares repurchased under the program will be held in treasury for future use.
	Series B Preferred Stock Conversion
	In 2008, the Company entered into a Securities Purchase Agreement (the “Purchase Agreement”) with two funds managed by Technology Crossover Ventures (the “Purchasers”), pursuant to which the Company sold to the Purchasers (i) 35,000 shares of the Company’s Series B Preferred Stock, which shares were convertible into an aggregate of 3,500,000 shares of common stock, and (ii) warrants (the “Warrants”) to purchase an aggregate of 700,000 shares of common stock at an exercise price of $10.00 per share, for an aggregate purchase price of $35.0 million. The net proceeds, after the placement agent fee and legal fees, were $33.5 million. The Warrants were exercisable for cash or on a net exercise basis. The Warrants were to expire on the tenth anniversary of the date they were first issued and were subject to customary anti-dilution adjustments in the event of stock splits, reverse stock splits, stock dividends and similar transactions.
	The shares of Series B Preferred Stock were convertible at any time by the holders thereof at a conversion price of $10.00 per share, subject to certain anti-dilution adjustments and also were subject to automatic conversion into shares of common stock if the closing price of the common stock was at least $17.50 on each trading day for a period of 65 consecutive trading days. In January 2011, all of the shares of the Series B Preferred Stock were mandatorily and automatically converted into 3,499,999 shares of common stock. In November 2011, a total of 455,465 shares of common stock were issued upon the exercise of the Warrants on a net exercise basis.
	Dividends
	The Company initiated a regular quarterly dividend in the fourth quarter of 2009. In addition to regular quarterly dividends, on December 27, 2012 the Company paid a special cash dividend of $1.30 per share. In January 2014, the Company’s Board of Directors approved a quarterly cash dividend of $0.16 per share payable on February 27, 2014 to stockholders of record as of the close of business on February 13, 2014. Any future declaration and payment of dividends will be at the sole discretion of the Company’s Board of Directors. The Board of Directors may take into account such matters as general business conditions, the Company’s financial results, capital requirements, contractual obligations, legal, and regulatory restrictions on the payment of dividends to the Company’s stockholders or by the Company’s subsidiaries to their respective parent entities, and any such other factors as the Board of Directors may deem relevant.

StockBased_Compensation_Plans

Stock-Based Compensation Plans	12 Months Ended
	Dec. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'
Stock-Based Compensation Plans	'
	10. Stock-Based Compensation Plans
	The Company has two stock incentive plans which provide for the grant of stock options, stock appreciation rights, restricted stock, performance shares, performance units, or other stock-based awards as incentives and rewards to encourage employees, consultants and non-employee directors to participate in the long-term success of the Company. As of December 31, 2013, 4,867,460 shares were available for grant under the stock incentive plans.
	Total stock-based compensation expense was as follows:
		Year Ended December 31,
		2013			2012			2011
		(In thousands)
	Employee:
	Restricted stock and performance shares	$	7,269		$	7,046		$	5,856
	Stock options		900			668			324
			8,169			7,714			6,180
	Non-employee directors:
	Restricted stock		710			671			679
	Total stock-based compensation	$	8,879		$	8,385		$	6,859
	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.
	Stock Options
	The exercise price of each option granted is equal to the market price of the Company’s common stock on the date of grant. Generally, option grants have provided for vesting over a three or five-year period. Options expire ten years from the date of grant. The fair value of each option award is estimated on the date of grant using the Black-Scholes option-pricing model. The determination of fair value of share-based payment awards on the date of grant using an option-pricing model is affected by the Company’s stock price as well as assumptions regarding a number of highly complex and subjective variables, including the expected stock price volatility over the term of the awards, the risk-free interest rate and the expected term. Expected volatilities are based on historical volatility of the Company’s stock and a peer group. The risk-free interest rate is based on U.S. Treasury securities with a maturity value approximating the expected term of the option. The expected term represents the period of time that options granted are expected to be outstanding based on actual and projected employee stock option exercise behavior.
	The weighted-average fair value for options granted during 2013, 2012 and 2011 was $19.61, $12.26 and $11.29, respectively. The following table represents the assumptions used for the Black-Scholes option-pricing model to determine the per share weighted-average fair value for options granted for the three years ended December 31, 2013:
		2013			2012			2011
	Expected life (years)		9.9			5			9.9
	Risk-free interest rate		1.9	%		0.7	%		3.3	%
	Expected volatility		44.3	%		48.2	%		48	%
	Expected dividend yield		1.2	%		1.2	%		1.3	%
	The following table reports stock option activity during the three years ended December 31, 2013 and the intrinsic value as of December 31, 2013:
								Remaining
		Number of			Weighted-Average			Contractual
		Shares			Exercise Price ($)			Term			Intrinsic Value ($)
											(In thousands)
	Outstanding at December 31, 2010		4,403,562			9.09
	Granted		340,771			21.6
	Canceled		(211,323	)		16.16
	Exercised		(1,605,273	)		10.21
	Outstanding at December 31, 2011		2,927,737			9.42
	Granted		13,292			32.45
	Canceled		—			—
	Exercised		(1,511,207	)		5.64
	Outstanding at December 31, 2012		1,429,822			13.62
	Granted		51,597			41.75
	Canceled		(4,348	)		33.84
	Exercised		(256,622	)		12.33						10,723
	Outstanding at December 31, 2013		1,220,449			15.01			4			63,369
	Exercisable at December 31, 2013		1,023,337			12.68			3.4			55,515
	The intrinsic value is the amount by which the closing price of the Company’s common stock on December 31, 2013 of $66.93 or the price on the day of exercise exceeds the exercise price of the stock options multiplied by the number of shares. As of December 31, 2013, there was $1.8 million of total unrecognized compensation cost related to non-vested stock options. That cost is expected to be recognized over a weighted-average period of 2.5 years.
	Restricted Stock and Performance Shares
	Restricted stock generally vests over a three or five-year period. Compensation expense is measured at the grant date and recognized ratably over the vesting period. Performance share awards are granted to certain senior managers. Each performance share award is earned or forfeited based on the level of achievement by the Company of pre-tax operating income on a per share basis before performance share and cash bonus expense. The pay-out ranges from zero to 150% of the performance share award. For each performance share earned, a participant is awarded an equal number of shares of restricted stock. Any restricted stock awarded to a participant vests and ceases to be restricted stock in two equal installments on each of the second and third anniversaries of the date of grant of the applicable performance share award. Compensation expense for performance shares is measured at the grant date and recognized on a graded basis over the vesting period. The pay-out achievement was 108.0%, 92.5%, and 145.0% of the performance award for 2013, 2012 and 2011, respectively. The following table reports performance share activity for the three years ended December 31, 2013:
	Performance year	2013			2012			2011
	Share pay-out at plan, net of forfeitures of 14,563 for 2011		42,908			44,843			63,102
	Actual share pay-out in following year		46,340			41,481			91,498
	Fair value per share on grant date	$	35.98		$	30.64		$	21.56
	The following table reports restricted stock and performance share activity during the three years ended December 31, 2013:
					Weighted-Average
		Number of			Grant Date Fair
		Restricted Shares			Value
	Outstanding at December 31, 2010		1,244,864		$	11.23
	Granted		435,548
	Performance share pay-out		130,552
	Canceled		(279,081	)
	Vested		(574,172	)
	Outstanding at December 31, 2011		957,711		$	15.69
	Granted		206,965
	Performance share pay-out		91,498
	Canceled		(7,390	)
	Vested		(497,525	)
	Outstanding at December 31, 2012		751,259		$	21.88
Granted		255,266
Performance share pay-out		41,481
Canceled		(93,358	)
Vested		(384,914	)
Outstanding at December 31, 2013		569,734		$	31.86
As of December 31, 2013, there was $11.2 million of total unrecognized compensation expense related to non-vested restricted stock and performance shares. That cost is expected to be recognized over a weighted-average period of 1.8 years.

Earnings_Per_Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2013
Earnings Per Share [Abstract]	'
Earnings Per Share	'
	11. Earnings Per Share
	The following table sets forth the computation of basic and diluted earnings per common share:
		Year Ended December 31,
		2013		2012			2011
		(In thousands, except per share amounts)
	Net income from continuing operations	$	68,563	$	61,784		$	49,447
	Net income (loss) from discontinued operations		7,453		(1,715	)		(1,743	)
	Net income	$	76,016	$	60,069		$	47,704
	Common stock—voting		36,886		36,101			34,420
	Common stock—non-voting		—		415			2,586
	Basic weighted average shares outstanding		36,886		36,516			37,006
	Basic earnings per common share
	Income from continuing operations	$	1.86	$	1.69		$	1.34
	Income (loss) from discontinued operations		0.2		(0.04	)		(0.05	)
	Basic earnings per share	$	2.06	$	1.65		$	1.29
	Weighted average shares outstanding		36,886		36,516			37,006
	Dilutive effect of stock options and restricted stock		1,002		1,300			2,602
	Diluted weighted average shares outstanding		37,888		37,816			39,608
	Diluted earnings per common share
	Income from continuing operations	$	1.81	$	1.64		$	1.25
	Income (loss) from discontinued operations		0.2		(0.05	)		(0.05	)
	Diluted earnings per share	$	2.01	$	1.59		$	1.2
	Stock options and restricted stock totaling 0.2 million shares, 0.1 million shares and 0.3 million shares for the years ended December 31, 2013, 2012 and 2011, 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_Facility

Credit Facility	12 Months Ended
	Dec. 31, 2013
Debt Disclosure [Abstract]	'
Credit Facility	'
	12. Credit Facility
	In January 2013, the Company entered into a three-year credit agreement (“Credit Agreement”) that provides for revolving loans and letters of credit up to an aggregate of $50.0 million (“Credit Facility”). As of December 31, 2013, there was $49.9 million available to borrow under the Credit Facility. Subject to satisfaction of certain specified conditions, the Company is permitted to upsize the Credit Facility by an additional $50.0 million in total.
	Borrowings under the Credit Facility will bear interest at a rate per annum equal to either of the following, as designated by the Company for each borrowing: (A) the sum of (i) the greatest of (a) the prime rate, as defined, (b) the federal funds effective rate plus 0.50% and (c) one month adjusted LIBOR plus 1.00% plus (ii) 0.50% or (B) the sum of (i) adjusted LIBOR plus (ii) 1.50%. Default interest is 2.00% per annum in excess of the rate otherwise applicable in the case of any overdue principal or any other overdue amount. The Company is also required to pay a commitment fee to the lenders under the Credit Facility in respect of unutilized revolving loan commitments at a rate of 0.30% per annum.
	The Company’s existing and future domestic subsidiaries (other than any broker-dealer subsidiary) have guaranteed the Company’s obligations under the Credit Agreement. Subject to customary exceptions and exclusions, the Credit Facility is 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 Facility, 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). Each of the Company and the guarantors will also be required to provide mortgages on any real property owned by it.
	The Credit Agreement requires that the Company’s consolidated total leverage ratio tested on the last day of each fiscal quarter not exceed 2.5 to 1.0. The Credit Agreement also requires that the Company’s consolidated interest coverage ratio tested on the last day of each fiscal quarter not fall below 3.5 to 1.0.
	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 judgments against the Company in excess of $10 million, the lenders would be entitled to accelerate the facility and take various other actions, including all actions permitted to be taken by a secured creditor. If certain bankruptcy events of default occur, the facility will automatically accelerate.

Commitments_and_Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2013
Commitments And Contingencies Disclosure [Abstract]	'
Commitments and Contingencies	'
	13. Commitments and Contingencies
	Lease Commitments
	The Company leases office space under non-cancelable lease agreements expiring at various dates through 2027. Office space leases are subject to escalation based on certain costs incurred by the landlord. Minimum rental commitments as of December 31, 2013 under such operating leases were as follows (in thousands):
	Year ending December 31,
	2014	$	1,477
	2015		1,699
	2016		2,840
	2017		2,764
	2018 and thereafter		18,471
		$	27,251
	Rental expense for the years ended December 31, 2013, 2012 and 2011 was $4.8 million, $2.1 million and $1.9 million, respectively, and is included in occupancy expense in the Consolidated Statements of Operations. Rental expense has been recorded based on the total minimum lease payments after giving effect to rent abatement and concessions, which are being amortized on a straight-line basis over the life of the lease. The Company is contingently obligated for standby letters of credit amounting to $1.3 million that were issued to landlords for office space.
	On August 29, 2013, the Company executed a lease for approximately 16,000 square feet of office space in London, England. The lease expires in January 2027.
	The Company has assigned two lease agreements on leased properties to separate third parties. The Company is contingently liable should the assignees default on future lease obligations through the lease termination dates of November 2015 and November 2020. The aggregate amount of future lease obligations under these arrangements is $2.8 million as of December 31, 2013.
	Employee Matter
	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 would establish an accrual for the loss. Once established, the accrual would be adjusted to reflect any relevant developments. When a loss contingency is not both probable and estimable, the Company does not establish an accrual.
	On January 2, 2013, a former employee of the Company filed a complaint against the Company with the U.S. Department of Labor alleging retaliatory employment practices in violation of the whistleblower provisions of the Sarbanes-Oxley Act. The relief sought includes, among other things, reinstatement, back pay and compensatory and punitive damages. The Company believes the complaint is without merit and intends to vigorously defend itself against the allegations. The Company filed its response to the complaint on February 26, 2013. Given the inherent uncertainty of the potential outcome of such proceedings, the Company cannot estimate the reasonably possible range of loss at this time. Based on the available information, the Company believes that the low end of the reasonably possible range of loss is zero and, accordingly, no loss accrual has been provided in the Company’s accompanying financial statements.
	Other
	The Company, through two regulated subsidiaries, executes certain bond transactions between and among institutional investor and broker-dealer clients on a riskless principal basis by serving as counterparty to both the buyer and the seller in trades which settle through a third-party clearing organization. Settlement typically occurs within one to three trading days after the trade date. Cash settlement of the transaction occurs upon receipt or delivery of the underlying instrument that was traded. For the year ended December 31, 2013, revenues from riskless principal trading were approximately $6.0 million. Under securities clearing agreements with the independent third party, the Company maintains a collateral deposit with the clearing broker in the form of cash. As of December 31, 2013, the amount of the collateral deposit included in prepaid expenses and other assets in the Consolidated Statements of Financial Condition was $0.9 million. The Company is exposed to credit risk in the event a counterparty does not fulfill its obligation to complete a transaction. Pursuant to the terms of the securities clearing agreements between the Company and the independent clearing broker, the clearing broker has the right to charge the Company for losses resulting from a counterparty’s failure to fulfill its contractual obligations. The losses are not capped at a maximum amount and apply to all trades executed through the clearing broker. At December 31, 2013, the Company had not recorded any liabilities with regard to this right.
	In the normal course of business, the Company enters into contracts that contain a variety of representations, warranties and general indemnifications. 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.

Sale_of_Discontinued_Operation

Sale of Discontinued Operations	12 Months Ended
	Dec. 31, 2013
Discontinued Operations And Disposal Groups [Abstract]	'
Sale of Discontinued Operations	'
	14. Sale of Discontinued Operations
	On September 30, 2013, the Company executed a stock purchase agreement to sell 100% of the outstanding shares of Greenline, a wholly owned subsidiary of the Company, to CameronTec Intressenter AB. The transaction closed on October 8, 2013. The aggregate purchase price was $11.0 million in cash, including a post-closing working capital adjustment. The Company recognized a gain on the disposition of $7.6 million, net of a tax benefit.
	Greenline’s operating results have been classified as discontinued operations in the Consolidated Statement of Operations. The following is a summary of Greenline’s operating results:
		Year Ended December 31,
		2013			2012			2011
		(In thousands)
	Revenues	$	6,137		$	7,364		$	9,227
	Expenses		6,384			10,048			11,944
	Loss before income taxes and gain on the sale from discontinued operations		(247	)		(2,684	)		(2,717	)
	Benefit for income taxes		(58	)		(969	)		(974	)
	Gain on the sale of discontinued operations, net of tax benefit		7,642			—			—
	Income (loss) from discontinued operations	$	7,453		$	(1,715	)	$	(1,743	)

Related_Party

Related Party	12 Months Ended
	Dec. 31, 2013
Related Party Transactions [Abstract]	'
Related Party	'
	15. Related Party
	In February 2012, the Company completed a registered underwritten secondary public offering of 3,597,333 shares of common stock held by JPM. The Company did not receive any of the proceeds of the offering. In addition, the Company repurchased 1,821,730 shares of non-voting common stock held by JPM. Immediately following the offering, JPM no longer held shares of common stock in the Company and is no longer considered a related party. The Company generated commissions, technology products and services revenues, information and user access fees, investment income and other income from JPM totaling $1.6 million and $7.5 million for the two months ended February 28, 2012 and the year ended December 31, 2011, respectively.

Segment_Information

Segment Information	12 Months Ended
	Dec. 31, 2013
Segment Reporting [Abstract]	'
Segment Information	'
	16. Segment Information
	The Company operates an electronic multi-party platform for the trading of fixed-income securities and provides related data analytics, compliance tools and post-trade services. The Company’s operations constitute a single business segment because of the highly integrated nature of these product and services, of the financial markets in which the Company competes and of 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.

Retirement_Savings_Plans

Retirement Savings Plans	12 Months Ended
	Dec. 31, 2013
Compensation And Retirement Disclosure [Abstract]	'
Retirement Savings Plans	'
	17. Retirement Savings Plans
	The Company, through its U.S. and U.K. subsidiaries, offers its employees the opportunity to invest in defined contribution plans. For the years ended December 31, 2013, 2012 and 2011, the Company contributed $0.8 million, $0.7 million and $0.7 million, respectively, to the plans.

Customer_Concentration

Customer Concentration	12 Months Ended
	Dec. 31, 2013
Risks And Uncertainties [Abstract]	'
Customer Concentration	'
	18. Customer Concentration
	During the years ended December 31, 2013, 2012 and 2011, no single client accounted for more than 10% of total revenue. One institutional investor client accounted for approximately 12.5%, 13.5% and 14.6% of trading volumes during the years ended December 31, 2013, 2012 and 2011, respectively. As of December 31, 2013, investment funds managed by this institutional investor client beneficially owned approximately 9% of the outstanding shares of the Company’s common stock, primarily through passive index and ETF funds.

Significant_Accounting_Policie1

Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2013
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.
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. The Company defines cash equivalents as short-term interest-bearing investments with maturities at the time of purchase of three months or less.
Securities Available-for-Sale	'
	Securities Available-for-Sale
	The Company classifies its marketable securities as available-for-sale securities. Unrealized marketable securities gains and losses, net of taxes, are reflected as a net amount under the caption of accumulated other comprehensive loss on the Consolidated Statements of Financial Condition. Realized gains and losses are recorded in the Consolidated Statements of Operations in other revenues. For the purpose of computing realized gains and losses, cost is determined on a specific identification basis.
	The Company assesses whether an other-than-temporary impairment loss on the 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 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 2013, 2012 or 2011.
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 portfolio and one foreign currency forward contract. All other financial instruments are short-term in nature and the carrying amount reported on our Consolidated Statements of Financial Condition 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.
	The allowance for doubtful accounts was $0.1 million, $0.1 million and $1.1 million as of December 31, 2013, 2012 and 2011, respectively. The provision for bad debts was $0.2 million, $0.2 million and $1.1 million for the years ended December 31, 2013, 2012 and 2011, respectively. During the fourth quarter of 2011, MF Global Inc., a broker-dealer market maker on the Company’s platform, entered a liquidation proceeding. In connection with the proceeding, the Company recorded a 100% allowance against outstanding receivables amounting to $0.9 million. Write-offs and other charges against the allowance for doubtful accounts were $0.1 million, $1.4 million and $0.2 million for the years ended December 31, 2013, 2012 and 2011, respectively.
Depreciation and Amortization	'
	Depreciation and Amortization
	Fixed assets are carried at cost less accumulated depreciation. The Company depreciates computer hardware and related software, office hardware and furniture and fixtures on a straight-line basis 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.
Cash Provided as Collateral	'
	Cash Provided as Collateral
	Cash is provided as collateral for electronic bank settlements and broker-dealer clearance 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 general and administrative expense 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 majority of the Company’s revenues are derived from commissions for trades executed on its platform and distribution fees that are billed to its broker-dealer clients on a monthly basis. The Company also derives revenues from information and post-trade services, technology products and services, investment income and other income.
	Commission revenue. Commissions are generally calculated as a percentage of the notional dollar volume of bonds traded on the platform and vary based on the type and maturity of the bond traded. Under the Company’s 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. For trades that the Company executes between and among institutional investor and broker-dealer clients on a riskless principal basis by serving as counterparty to both the buyer and the seller, the Company earns the commission through the difference in price between the two riskless principal trades. Fee programs for certain products include distribution fees which are recognized monthly.
	Information and post-trade services. The Company generates revenue from information services provided to its broker-dealer clients, institutional investor clients and data-only subscribers. Information services are invoiced monthly, quarterly or annually. When billed in advance, revenues are recognized monthly on a straight-line basis. The Company also generates revenue from trade matching and regulatory transaction reporting services. Revenue is recognized in the period the services are provided.
	Technology products and services. The Company generates revenues from technology software licenses, maintenance and support services (referred to as post-contract technical support or “PCS”) and professional consulting services. Revenue is generally recognized when persuasive evidence of an arrangement exists, delivery has occurred, the fee is fixed or determinable and collection is considered probable. The Company generally sells software licenses and PCS together as part of multiple-element arrangements. The Company also enters into contracts for technology integration consulting services unrelated to any software product.
	For arrangements that include multiple elements, generally software licenses and PCS, the Company allocates and defers revenue for the undelivered items based on vendor specific objective evidence (“VSOE”) of the fair value of the undelivered elements and recognizes the difference between the total arrangement fee and the amount deferred for the undelivered items as license revenue. The Company’s VSOE of each element is based on historical evidence of stand-alone sales of these elements to third parties or the stated renewal rate for the undelivered elements. When VSOE does not exist for undelivered items, the entire arrangement fee is recognized ratably over the performance period. For PCS, the term is typically one year and revenue is recognized over the duration of the arrangement on a straight-line basis.
	Professional consulting services are generally separately priced and are typically not essential to the functionality of the Company’s software products. Revenues from these services are recognized separately from the license fee. Generally, revenue from time-and-materials consulting contracts is recognized as services are performed.
	Revenues from contracts for technology integration consulting services are recognized on the percentage-of-completion method. Percentage-of-completion accounting involves calculating the percentage of services provided during the reporting period compared to the total estimated services to be provided over the duration of the contract. If estimates indicate that a contract loss will occur, a loss provision is recorded in the period in which the loss first becomes probable and reasonably estimable. Contract losses are determined to be the amount by which the estimated direct and indirect costs of the contract exceed the estimated total revenues that will be generated by the contract. There were no contract loss provisions recorded as of December 31, 2013, 2012 and 2011. Revenues recognized in excess of billings are recorded as unbilled services within other assets. Billings in excess of revenues recognized are recorded as deferred revenues until revenue recognition criteria are met.
	Initial set-up fees. The Company enters into agreements with its broker-dealer clients pursuant to which the Company provides access to its platform through a non-exclusive and non-transferable license. Broker-dealer clients may pay an initial set-up fee, which is typically due and payable upon execution of the broker-dealer agreement. The initial set-up fee, if any, varies by agreement. Revenue is recognized over the initial term of the agreement, which is generally two years. Initial set-up fees are reported in other income in the Consolidated Statements of Operations.
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.
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.
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 is judgmental in nature 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 U.S. generally accepted accounting principles 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.
Out-of-Period Adjustment	'
	Out-of-Period Adjustment
	During the second quarter of 2013, the Company determined that it had incorrectly excluded incentive compensation as a component of employee compensation eligible for capitalization under its software development costs capitalization policy. The Company assessed this error and determined that it was not material to previous reporting periods and is not material to the current year. Therefore, the Company recorded this item as an out-of-period adjustment in the three months ended June 30, 2013 by reducing employee compensation and benefits expense by $2.9 million and increasing depreciation and amortization expense by $1.3 million in the Consolidated Statements of Operations and increasing the net book value of capitalized software by $1.6 million in the Consolidated Statements of Financial Condition. This item was reflected as a non-cash adjustment in the Consolidated Statements of Cash Flows.
Recent Accounting Pronouncements	'
	Recent Accounting Pronouncements
	In 2012, the Financial Accounting Standards Board issued new guidance related to the Statement of Comprehensive Income. Reclassification adjustments out of accumulated other comprehensive income are required on the face of the Consolidated Statement of Comprehensive Income. This accounting standard is effective for fiscal years beginning on or after December 15, 2012. The Company adopted the new guidance effective January 1, 2013.

Net_Capital_Requirements_and_C1

Net Capital Requirements and Customer Protection Requirements (Tables)	12 Months Ended
	Dec. 31, 2013
Text Block [Abstract]	'
Net Capital Requirements and Customer Protection Requirements	'
	The following table sets forth the capital requirements, as defined, that the Company’s subsidiaries were required to maintain as of December 31, 2013:
		MarketAxess		MarketAxess		MarketAxess
		Corporation		Europe Limited		Canada Company
		(In thousands)
	Net capital	$	86,367	$	17,792	$	865
	Minimum net capital required		1,859		3,227		259
	Excess net capital	$	84,508	$	14,565	$	606

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2013
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 December 31, 2013
	Money market funds	$	90,536		$	—		$	—		$	90,536
	Securities available-for-sale
	Municipal securities		—			16,052			—			16,052
	Corporate bonds		—			51,690			—			51,690
	Foreign currency forward position		—			(472	)		—			(472	)
		$	90,536		$	67,270		$	—		$	157,806
	As of December 31, 2012
	Money market funds	$	83,519		$	—		$	—		$	83,519
	Securities available-for-sale
	U.S. government obligations		—			31,104			—			31,104
	Municipal securities		—			17,947			—			17,947
	Corporate bonds		—			2,157			—			2,157
	Foreign currency forward and option contracts		—			15			—			15
		$	83,519		$	51,223		$	—		$	134,742
Summary of Foreign Currency Forward Contracts	'
	A summary of the foreign currency forward contracts is as follows:
		As of December 31,
		2013			2012
		(In thousands)
	Notional value	$	29,431		$	15,792
	Fair value of notional		29,903			15,809
	Fair value of the liability	$	(472	)	$	(17	)
Summary of Company's Securities Available-for-Sale	'
	The following is a summary of the Company’s securities available-for-sale:
					Gross			Gross			Estimated
		Amortized			unrealized			unrealized			fair
		cost			gains			losses			value
		(In thousands)
	As of December 31, 2013
	Municipal securities	$	16,049		$	9		$	(6	)	$	16,052
	Corporate bonds		51,579			124			(13	)		51,690
	Total securities available-for-sale	$	67,628		$	133		$	(19	)	$	67,742
	As of December 31, 2012
	U.S. government obligations	$	30,255		$	849		$	—		$	31,104
	Municipal securities		17,941			10			(4	)		17,947
	Corporate bonds		2,159			—			(2	)		2,157
	Total securities available-for-sale	$	50,355		$	859		$	(6	)	$	51,208
Summary of Contractual Maturities of Securities Available-for-Sale	'
	The following table summarizes the contractual maturities of securities available-for-sale:
		As of December 31,
		2013			2012
		(In thousands)
	Less than one year	$	12,332		$	10,870
	Due in 1—5 years		55,410			40,338
	Total securities available-for-sale	$	67,742		$	51,208
Fair Values and Unrealized Losses on Securities Available-for-Sale	'
	The following table provides fair values and unrealized losses on securities available-for-sale and by the aging of the securities’ continuous unrealized loss position:
		Less than Twelve Months						Twelve Months or More						Total
		Estimated			Gross			Estimated			Gross			Estimated		Gross
		fair			unrealized			fair			unrealized			fair		unrealized
		value			losses			value			losses			value		losses
		(In thousands)
	As of December 31, 2013
	Municipal securities	$	4,955		$	(6	)	$	—		$	—		$	4,955	$	(6	)
	Corporate bonds		10,728			(13	)		—			—			10,728		(13	)
	Total	$	15,683		$	(19	)	$	—		$	—		$	15,683	$	(19	)
	As of December 31, 2012
	U.S. government obligations	$	—		$	—		$	—		$	—		$	—	$	—
	Municipal securities		2,780			(4	)		—			—			2,780		(4	)
	Corporate bonds		2,157			(2	)		—			—			2,157		(2	)
	Total	$	4,937		$	(6	)	$	—		$	—		$	4,937	$	(6	)

Acquisition_Tables

Acquisition (Tables)	12 Months Ended
	Dec. 31, 2013
Business Combinations [Abstract]	'
Preliminary Purchase Price Allocation	'
	The purchase price allocation is as follows (in thousands):
	Purchase price	$	46,683
	Less: acquired cash		(8,856	)
	Purchase price, net of acquired cash		37,827
	Accounts receivable		3,733
	Intangible assets		13,255
	Other assets		1,718
	Deferred tax liability, net		(2,342	)
	Accounts payable, accrued expenses and deferred revenue		(4,622	)
	Goodwill	$	26,085
Summary of Acquired Intangible Assets	'
	The acquired intangible assets are as follows (in thousands, except for useful lives):
		Costs			Useful Lives
	Customer relationships	$	5,455		10-15 years
	Internally developed software		5,000		3 years
	Tradename- indefinite life		1,820		indefinite
	Tradename- finite life		300		3 years
	Non-compete agreement		380		3 years
	Other		300		indefinite
	Total	$	13,255
Pro forma Financial Information	'
	The pro forma financial information includes the amortization charges from acquired intangible assets, adjustments to interest income to reflect the cash purchase price and related tax effects.
		Pro forma
		Year Ended December 31,
		2013			2012		2011
		(In thousands, except per share amounts)
	Revenues	$	242,657		$	214,683	$	195,741
	Income before income taxes	$	107,316		$	88,361	$	82,769
	Net income	$	68,579		$	61,210	$	50,560
	Basic net income per common share	$	1.86		$	1.68	$	1.37
	Diluted net income per common share	$	1.81		$	1.62	$	1.28

Goodwill_and_Intangible_Assets1

Goodwill and Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2013
Goodwill And Intangible Assets Disclosure [Abstract]	'
Schedule of Changes in Goodwill and Intangible Assets with Indefinite Lives	'
	The following is a summary of changes in goodwill and intangible assets with indefinite lives for the year ended December 31, 2013 (in thousands):
	Balance at beginning of period	$	31,785
	Goodwill from Xtrakter acquisition		26,085
	Intangible assets with indefinite lives from Xtrakter acquisition		2,120
	Less: Goodwill ascribed to discontinued operations		(277	)
	Balance at end of period	$	59,713
Summary of Company's Intangible Assets	'
	Intangible assets that are subject to amortization, including the related accumulated amortization, are comprised of the following:
		December 31, 2013								December 31, 2012
		Cost			Accumulated			Net		Cost		Accumulated			Net
					Amortization			Carrying				Amortization			Carrying
								Amount							Amount
		(In thousands)
	Technology	$	5,770		$	(2,159	)	$	3,611	$	4,010	$	(3,892	)	$	118
	Customer relationships		5,698			(816	)		4,882		3,530		(2,364	)		1,166
	Non-competition agreements		380			(106	)		274		1,260		(1,214	)		46
	Tradenames		370			(153	)		217		590		(570	)		20
	Total	$	12,218		$	(3,234	)	$	8,984	$	9,390	$	(8,040	)	$	1,350

Capitalized_Software_Furniture1

Capitalized Software, Furniture, Equipment and Leasehold Improvements (Tables)	12 Months Ended
	Dec. 31, 2013
Property Plant And Equipment [Abstract]	'
Capitalized Software Development Costs, Furniture, Equipment and Leasehold Improvements, Net of Accumulated Depreciation and Amortization	'
	Capitalized software development costs, furniture, equipment and leasehold improvements, net of accumulated depreciation and amortization, are comprised of the following:
		As of December 31,
		2013			2012
		(In thousands)
	Software development costs	$	41,062		$	30,482
	Computer hardware and related software		22,051			15,702
	Office hardware		2,380			2,125
	Furniture and fixtures		1,777			1,479
	Leasehold improvements		8,129			4,709
	Computer hardware under capital lease		1,419			1,419
	Accumulated depreciation and amortization		(44,115	)		(37,907	)
	Total capitalized software, furniture, equipment and leasehold improvements, net of accumulated depreciation and amortization	$	32,703		$	18,009

Income_Taxes_Tables

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2013
Income Tax Disclosure [Abstract]	'
Schedule of Provision for Income Taxes	'
	The provision for income taxes from continuing operations consists of the following:
		Year Ended December 31,
		2013			2012			2011
		(In thousands)
	Current:
	Federal	$	26,071		$	14,402		$	6,187
	State and local		5,958			2,287			2,849
	Foreign		1,014			1,315			1,194
	Total current provision		33,043			18,004			10,230
	Deferred:
	Federal		5,507			8,542			19,090
	State and local		812			1,046			2,667
	Foreign		(645	)		(6	)		16
	Total deferred provision		5,674			9,582			21,773
	Provision for income taxes	$	38,717		$	27,586		$	32,003
Difference Between the Company's Reported Provision for Income Taxes and the U.S. Federal Statutory Rate	'
	The difference between the Company’s reported provision for income taxes and the U.S. federal statutory rate of 35% is as follows:
		Year Ended December 31,
		2013			2012			2011
	U.S. federal tax at statutory rate		35	%		35	%		35	%
	State and local taxes—net of federal benefit		4.1			2.4			4.9
	Release of previously unrecognized tax benefits		—			(7.5	)		—
	Other, net		(3.0	)		1			(0.6	)
	Provision for income taxes		36.1	%		30.9	%		39.3	%
Summary of Company's Net Deferred Tax Assets	'
	The following is a summary of the Company’s net deferred tax assets:
		As of December 31,
		2013			2012
		(In thousands)
	Deferred tax assets
	U.S. net operating loss carryforwards	$	4,273		$	7,175
	Foreign net operating loss carryforwards		101			160
	Capital loss carryforwards		7,487			—
	Stock compensation expense		6,022			5,296
	Other		3,206			2,839
	Total deferred tax assets		21,089			15,470
	Valuation allowance		(7,743	)		(727	)
	Net deferred tax assets		13,346			14,743
	Deferred tax liabilities
	Depreciation and amortization		(1,905	)		(2,025	)
	Capitalized software development costs		(4,163	)		(2,752	)
	Intangible assets		(2,331	)		(524	)
	Deferred tax assets, net	$	4,947		$	9,442
Summary of Changes in Valuation Allowance	'
	A summary of the changes in the valuation allowance follows:
		Year Ended December 31,
		2013			2012			2011
		(In thousands)
	Valuation allowance at beginning of year	$	727		$	287		$	249
	Increase (decrease) to valuation allowance attributable to:
	Current year income		(65	)		440			38
	State net operating loss		(406	)		—			—
	Capital loss		7,487			—			—
	Valuation allowance at end of year	$	7,743		$	727		$	287
Reconciliation of the Unrecognized Tax Benefits	'
	A reconciliation of the unrecognized tax benefits is as follows:
		Year Ended December 31,
		2013			2012			2011
		(In thousands)
	Balance at beginning of year	$	49		$	3,647		$	3,329
	Additions for tax positions of prior years		—			—			366
	Additions for tax positions of current year		235			—			—
	Reductions for tax positions of prior years		(19	)		(3,598	)		(48	)
	Balance at end of year	$	265		$	49		$	3,647

StockBased_Compensation_Plans_

Stock-Based Compensation Plans (Tables)	12 Months Ended
	Dec. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'
Stock-Based Compensation Expense	'
	Total stock-based compensation expense was as follows:
		Year Ended December 31,
		2013			2012			2011
		(In thousands)
	Employee:
	Restricted stock and performance shares	$	7,269		$	7,046		$	5,856
	Stock options		900			668			324
			8,169			7,714			6,180
	Non-employee directors:
	Restricted stock		710			671			679
	Total stock-based compensation	$	8,879		$	8,385		$	6,859
Assumptions Used for the Black-Scholes Option-Pricing Model to Determine the Per Share Weighted Average Fair Value for Options Granted	'
	The following table represents the assumptions used for the Black-Scholes option-pricing model to determine the per share weighted-average fair value for options granted for the three years ended December 31, 2013:
		2013			2012			2011
	Expected life (years)		9.9			5			9.9
	Risk-free interest rate		1.9	%		0.7	%		3.3	%
	Expected volatility		44.3	%		48.2	%		48	%
	Expected dividend yield		1.2	%		1.2	%		1.3	%
Stock Option Activity	'
	The following table reports stock option activity during the three years ended December 31, 2013 and the intrinsic value as of December 31, 2013:
								Remaining
		Number of			Weighted-Average			Contractual
		Shares			Exercise Price ($)			Term			Intrinsic Value ($)
											(In thousands)
	Outstanding at December 31, 2010		4,403,562			9.09
	Granted		340,771			21.6
	Canceled		(211,323	)		16.16
	Exercised		(1,605,273	)		10.21
	Outstanding at December 31, 2011		2,927,737			9.42
	Granted		13,292			32.45
	Canceled		—			—
	Exercised		(1,511,207	)		5.64
	Outstanding at December 31, 2012		1,429,822			13.62
	Granted		51,597			41.75
	Canceled		(4,348	)		33.84
	Exercised		(256,622	)		12.33						10,723
	Outstanding at December 31, 2013		1,220,449			15.01			4			63,369
	Exercisable at December 31, 2013		1,023,337			12.68			3.4			55,515
Summary of Performance of Share Activity	'
	The following table reports performance share activity for the three years ended December 31, 2013:
	Performance year	2013			2012			2011
	Share pay-out at plan, net of forfeitures of 14,563 for 2011		42,908			44,843			63,102
	Actual share pay-out in following year		46,340			41,481			91,498
	Fair value per share on grant date	$	35.98		$	30.64		$	21.56
Restricted Stock and Performance Share Activity	'
	The following table reports restricted stock and performance share activity during the three years ended December 31, 2013:
					Weighted-Average
		Number of			Grant Date Fair
		Restricted Shares			Value
	Outstanding at December 31, 2010		1,244,864		$	11.23
	Granted		435,548
	Performance share pay-out		130,552
	Canceled		(279,081	)
	Vested		(574,172	)
	Outstanding at December 31, 2011		957,711		$	15.69
	Granted		206,965
	Performance share pay-out		91,498
	Canceled		(7,390	)
	Vested		(497,525	)
	Outstanding at December 31, 2012		751,259		$	21.88
	Granted		255,266
	Performance share pay-out		41,481
	Canceled		(93,358	)
	Vested		(384,914	)
	Outstanding at December 31, 2013		569,734		$	31.86

Earnings_Per_Share_Tables

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2013
Earnings Per Share [Abstract]	'
Computation of Basic and Diluted Earnings Per Common Share	'
	The following table sets forth the computation of basic and diluted earnings per common share:
		Year Ended December 31,
		2013		2012			2011
		(In thousands, except per share amounts)
	Net income from continuing operations	$	68,563	$	61,784		$	49,447
	Net income (loss) from discontinued operations		7,453		(1,715	)		(1,743	)
	Net income	$	76,016	$	60,069		$	47,704
	Common stock—voting		36,886		36,101			34,420
	Common stock—non-voting		—		415			2,586
	Basic weighted average shares outstanding		36,886		36,516			37,006
	Basic earnings per common share
	Income from continuing operations	$	1.86	$	1.69		$	1.34
	Income (loss) from discontinued operations		0.2		(0.04	)		(0.05	)
	Basic earnings per share	$	2.06	$	1.65		$	1.29
	Weighted average shares outstanding		36,886		36,516			37,006
	Dilutive effect of stock options and restricted stock		1,002		1,300			2,602
	Diluted weighted average shares outstanding		37,888		37,816			39,608
	Diluted earnings per common share
	Income from continuing operations	$	1.81	$	1.64		$	1.25
	Income (loss) from discontinued operations		0.2		(0.05	)		(0.05	)
	Diluted earnings per share	$	2.01	$	1.59		$	1.2

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2013
Commitments And Contingencies Disclosure [Abstract]	'
Summary of Minimum Rental Commitments under Operating Leases	'
	Minimum rental commitments as of December 31, 2013 under such operating leases were as follows (in thousands):
	2014		1,477
	2015		1,699
	2016		2,840
	2017		2,764
	2018 and thereafter		18,471
		$	27,251

Sale_of_Discontinued_Operation1

Sale of Discontinued Operations (Tables)	12 Months Ended
	Dec. 31, 2013
Discontinued Operations And Disposal Groups [Abstract]	'
Summary of Greenline's Operating Results	'
	The following is a summary of Greenline’s operating results:
		Year Ended December 31,
		2013			2012			2011
		(In thousands)
	Revenues	$	6,137		$	7,364		$	9,227
	Expenses		6,384			10,048			11,944
	Loss before income taxes and gain on the sale from discontinued operations		(247	)		(2,684	)		(2,717	)
	Benefit for income taxes		(58	)		(969	)		(974	)
	Gain on the sale of discontinued operations, net of tax benefit		7,642			—			—
	Income (loss) from discontinued operations	$	7,453		$	(1,715	)	$	(1,743	)

Organization_and_Principal_Bus1

Organization and Principal Business Activity - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2013
Accounting Policies [Abstract]	'
Date of incorporation	11-Apr-00

Significant_Accounting_Policie2

Significant Accounting Policies - Additional Information (Detail) (USD $)	12 Months Ended				12 Months Ended	3 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2013	Jun. 30, 2013	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2013
				Forward Contracts [Member]	Internally Developed Software [Member]	Restatement Adjustment [Member]	MF Global Inc [Member]	Minimum [Member]	Minimum [Member]	Maximum [Member]	Maximum [Member]
				Contract					Business Combinations [Member]		Business Combinations [Member]
Property, Plant and Equipment [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Maximum maturity period for classification of investments as cash equivalents	'3 months	'	'	'	'	'	'	'	'	'	'
Investments other-than-temporary losses	$0	$0	$0	'	'	'	'	'	'	'	'
Number of foreign currency contracts	'	'	'	1	'	'	'	'	'	'	'
Contractual maturities accounts receivable	'less than one year	'	'	'	'	'	'	'	'	'	'
Allowance for doubtful accounts	133,000	75,000	1,100,000	'	'	'	'	'	'	'	'
Provision for bad debts	200,000	500,000	1,200,000	'	'	'	900,000	'	'	'	'
Percentage of allowance against outstanding receivables	100.00%	'	'	'	'	'	'	'	'	'	'
Write-offs and other charges against the allowance for doubtful accounts	100,000	1,400,000	200,000	'	'	'	'	'	'	'	'
Estimated useful lives of amortizable intangibles	'	'	'	'	'	'	'	'3 years	'	'7 years	'
Estimated life of intangible assets	'	'	'	'	'3 years	'	'	'3 years	'5 years	'15 years	'10 years
Term for post-contract technical support	'1 year	'	'	'	'	'	'	'	'	'	'
Contract loss provisions recorded	0	0	0	'	'	'	'	'	'	'	'
Term of agreement for revenue recognition	'2 years	'	'	'	'	'	'	'	'	'	'
Employee compensation and benefit expense	'	'	'	'	'	2,900,000	'	'	'	'	'
Depreciation and amortization	14,123,000	6,758,000	5,206,000	'	'	1,300,000	'	'	'	'	'
Furniture, equipment, leasehold improvements and capitalized software, net of accumulated depreciation and amortization	$32,703,000	$18,009,000	'	'	'	$1,600,000	'	'	'	'	'

Net_Capital_Requirements_and_C2

Net Capital Requirements and Customer Protection Requirements - Additional Information (Detail) (USD $)	Dec. 31, 2013
Brokers And Dealers [Abstract]	'
Minimum net capital required	$250,000
Percentage of aggregate indebtedness	0.0667
Estimated maintenance of financial resources	$6,000,000

Net_Capital_Requirements_and_C3

Net Capital Requirements and Customer Protection Requirements - Net Capital Requirements and Customer Protection Requirements (Detail) (USD $)	Dec. 31, 2013
Adjusted Capital Requirements And Customer Protection Requirements [Line Items]	'
Minimum net capital required	$250,000
MarketAxess Corporation [Member]	'
Adjusted Capital Requirements And Customer Protection Requirements [Line Items]	'
Net capital	86,367,000
Minimum net capital required	1,859,000
Excess net capital	84,508,000
MarketAxess Europe Limited [Member]	'
Adjusted Capital Requirements And Customer Protection Requirements [Line Items]	'
Net capital	17,792,000
Minimum net capital required	3,227,000
Excess net capital	14,565,000
Marketaxess Canada Company [Member]	'
Adjusted Capital Requirements And Customer Protection Requirements [Line Items]	'
Net capital	865,000
Minimum net capital required	259,000
Excess net capital	$606,000

Fair_Value_Measurements_Valuat

Fair Value Measurements - Valuation of Company's Assets and Liabilities Measured at Fair Value (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Money market funds	$90,536	$83,519
Securities available-for-sale	67,742	51,208
Foreign currency forward position	-472	15
Assets Fair Value Total	157,806	134,742
Municipal Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities available-for-sale	16,052	17,947
Corporate Bonds [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities available-for-sale	51,690	2,157
U.S. Government Obligations [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities available-for-sale	'	31,104
Level 1 [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Money market funds	90,536	83,519
Foreign currency forward position	'	'
Assets Fair Value Total	90,536	83,519
Level 1 [Member] | Municipal Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities available-for-sale	'	'
Level 1 [Member] | Corporate Bonds [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities available-for-sale	'	'
Level 1 [Member] | U.S. Government Obligations [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities available-for-sale	'	'
Level 2 [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Money market funds	'	'
Foreign currency forward position	-472	15
Assets Fair Value Total	67,270	51,223
Level 2 [Member] | Municipal Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities available-for-sale	16,052	17,947
Level 2 [Member] | Corporate Bonds [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities available-for-sale	51,690	2,157
Level 2 [Member] | U.S. Government Obligations [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities available-for-sale	'	31,104
Level 3 [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Money market funds	'	'
Foreign currency forward position	'	'
Assets Fair Value Total	'	'
Level 3 [Member] | Municipal Securities [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities available-for-sale	'	'
Level 3 [Member] | Corporate Bonds [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities available-for-sale	'	'
Level 3 [Member] | U.S. Government Obligations [Member]	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Securities available-for-sale	'	'

Fair_Value_Measurements_Additi

Fair Value Measurements - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Fair Value Disclosures [Abstract]	'	'	'
Hedge derivative expiration period	'One-month period	'	'
Proceeds from the sales and maturities of securities available-for-sale	$43.40	$42	$27.40

Fair_Value_Measurements_Summar

Fair Value Measurements - Summary of Foreign Currency Forward Contract (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Foreign Exchange Contracts [Line Items]	'	'
Fair value of the liability	($472)	($17)
Foreign Exchange Contract [Member]	'	'
Foreign Exchange Contracts [Line Items]	'	'
Notional value	29,431	15,792
Fair value of notional	$29,903	$15,809

Fair_Value_Measurements_Summar1

Fair Value Measurements - Summary of Company's Securities Available-for-Sale (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized cost	$67,628	$50,355
Gross unrealized gains	133	859
Gross unrealized losses	-19	-6
Securities available-for-sale, Estimated fair value	67,742	51,208
Municipal Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized cost	16,049	17,941
Gross unrealized gains	9	10
Gross unrealized losses	-6	-4
Securities available-for-sale, Estimated fair value	16,052	17,947
Corporate Bonds [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized cost	51,579	2,159
Gross unrealized gains	124	'
Gross unrealized losses	-13	-2
Securities available-for-sale, Estimated fair value	51,690	2,157
U.S. Government Obligations [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized cost	'	30,255
Gross unrealized gains	'	849
Gross unrealized losses	'	'
Securities available-for-sale, Estimated fair value	'	$31,104

Fair_Value_Measurements_Summar2

Fair Value Measurements - Summary of Contractual Maturities of Securities Available-for-Sale (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Fair Value Disclosures [Abstract]	'	'
Less than one year	$12,332	$10,870
Due in 1-5 years	55,410	40,338
Securities available-for-sale, Estimated fair value	$67,742	$51,208

Fair_Value_Measurements_Fair_V

Fair Value Measurements - Fair Values and Unrealized Losses on Securities Available-for-Sale (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]	'	'
Less than Twelve Months, Estimated fair value	$15,683	$4,937
Less than Twelve Months, Gross unrealized losses	-19	-6
Twelve Months or More, Estimated fair value	'	'
Twelve Months or More, Gross unrealized losses	'	'
Estimated fair value, Total	15,683	4,937
Gross unrealized losses, Total	-19	-6
Municipal Securities [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Less than Twelve Months, Estimated fair value	4,955	2,780
Less than Twelve Months, Gross unrealized losses	-6	-4
Twelve Months or More, Estimated fair value	'	'
Twelve Months or More, Gross unrealized losses	'	'
Estimated fair value, Total	4,955	2,780
Gross unrealized losses, Total	-6	-4
Corporate Bonds [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Less than Twelve Months, Estimated fair value	10,728	2,157
Less than Twelve Months, Gross unrealized losses	-13	-2
Twelve Months or More, Estimated fair value	'	'
Twelve Months or More, Gross unrealized losses	'	'
Estimated fair value, Total	10,728	2,157
Gross unrealized losses, Total	-13	-2
U.S. Government Obligations [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Less than Twelve Months, Estimated fair value	'	'
Less than Twelve Months, Gross unrealized losses	'	'
Twelve Months or More, Estimated fair value	'	'
Twelve Months or More, Gross unrealized losses	'	'
Estimated fair value, Total	'	'
Gross unrealized losses, Total	'	'

Acquisition_Additional_Informa

Acquisition - Additional Information (Detail) (USD $)	12 Months Ended			1 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Feb. 28, 2013	Dec. 31, 2013
				Xtrakter Limited [Member]	Xtrakter Limited [Member]
Business Acquisition [Line Items]	'	'	'	'	'
Aggregate business acquisition purchase price	$37,827,000	'	'	$37,800,000	'
Professional services	'	'	'	'	1,600,000
Revenue	238,733,000	190,840,000	171,874,000	'	18,400,000
Net income	'	'	'	'	$900,000

Acquisition_Preliminary_Purcha

Acquisition - Preliminary Purchase Price Allocation (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013
Business Combinations [Abstract]	'
Purchase price	$46,683
Less: acquired cash	-8,856
Purchase price, net of acquired cash	37,827
Accounts receivable	3,733
Intangible assets	13,255
Other assets	1,718
Deferred tax liability, net	-2,342
Accounts payable, accrued expenses and deferred revenue	-4,622
Goodwill	$26,085

Acquisition_Summary_of_Acquire

Acquisition - Summary of Acquired Intangible Assets (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013
Acquired Intangible Assets [Line Items]	'
Costs	$13,255
Tradename - Indefinite Life [Member]	'
Acquired Intangible Assets [Line Items]	'
Costs	1,820
Other [Member]	'
Acquired Intangible Assets [Line Items]	'
Costs	300
Customer Relationships [Member]	'
Acquired Intangible Assets [Line Items]	'
Costs	5,455
Internally Developed Software [Member]	'
Acquired Intangible Assets [Line Items]	'
Costs	5,000
Useful Lives	'3 years
Tradenames - Finite Life [Member]	'
Acquired Intangible Assets [Line Items]	'
Costs	300
Useful Lives	'3 years
Non-Competition Agreements [Member]	'
Acquired Intangible Assets [Line Items]	'
Costs	$380
Useful Lives	'3 years
Minimum [Member]	'
Acquired Intangible Assets [Line Items]	'
Useful Lives	'3 years
Minimum [Member] | Customer Relationships [Member]	'
Acquired Intangible Assets [Line Items]	'
Useful Lives	'10 years
Maximum [Member]	'
Acquired Intangible Assets [Line Items]	'
Useful Lives	'15 years
Maximum [Member] | Customer Relationships [Member]	'
Acquired Intangible Assets [Line Items]	'
Useful Lives	'15 years

Acquisition_Pro_forma_Financia

Acquisition - Pro forma Financial Information (Detail) (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Business Combinations [Abstract]	'	'	'
Revenues	$242,657	$214,683	$195,741
Income before income taxes	107,316	88,361	82,769
Net income	$68,579	$61,210	$50,560
Basic net income per common share	$1.86	$1.68	$1.37
Diluted net income per common share	$1.81	$1.62	$1.28

Goodwill_and_Intangible_Assets2

Goodwill and Intangible Assets - Schedule of Changes in Goodwill and Intangible Assets with Indefinite Lives (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013
Goodwill And Intangible Assets Disclosure [Abstract]	'
Balance at beginning of period	$31,785
Goodwill from Xtrakter acquisition	26,085
Intangible assets with indefinite lives from Xtrakter acquisition	2,120
Less: Goodwill ascribed to discontinued operations	-277
Balance at end of period	$59,713

Goodwill_and_Intangible_Assets3

Goodwill and Intangible Assets - Summary of Company's Intangible Assets (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Finite-Lived Intangible Assets [Line Items]	'	'
Cost	$12,218	$9,390
Accumulated Amortization	-3,234	-8,040
Net Carrying Amount	8,984	1,350
Technology [Member]	'	'
Finite-Lived Intangible Assets [Line Items]	'	'
Cost	5,770	4,010
Accumulated Amortization	-2,159	-3,892
Net Carrying Amount	3,611	118
Customer Relationships [Member]	'	'
Finite-Lived Intangible Assets [Line Items]	'	'
Cost	5,698	3,530
Accumulated Amortization	-816	-2,364
Net Carrying Amount	4,882	1,166
Non-Competition Agreements [Member]	'	'
Finite-Lived Intangible Assets [Line Items]	'	'
Cost	380	1,260
Accumulated Amortization	-106	-1,214
Net Carrying Amount	274	46
Tradenames - Finite Life [Member]	'	'
Finite-Lived Intangible Assets [Line Items]	'	'
Cost	370	590
Accumulated Amortization	-153	-570
Net Carrying Amount	$217	$20

Goodwill_and_Intangible_Assets4

Goodwill and Intangible Assets - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Goodwill And Intangible Assets Disclosure [Abstract]	'	'
Amortization expense associated with identifiable intangible assets	$2,200,000	$42,000
Estimated total amortization expense 2014	2,300,000	'
Estimated total amortization expense 2015	2,300,000	'
Estimated total amortization expense 2016	700,000	'
Estimated total amortization expense 2017	400,000	'
Estimated total amortization expense 2018	$400,000	'

Capitalized_Software_Furniture2

Capitalized Software, Furniture, Equipment and Leasehold Improvements - Capitalized Software Development Costs, Furniture, Equipment and Leasehold Improvements, Net of Accumulated Depreciation and Amortization (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Property, Plant and Equipment [Line Items]	'	'
Accumulated depreciation and amortization	($44,115)	($37,907)
Total capitalized software, furniture, equipment and leasehold improvements, net of accumulated depreciation and amortization	32,703	18,009
Software Development Costs [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Total capitalized software, furniture, equipment and leasehold improvements, net of accumulated depreciation and amortization	41,062	30,482
Computer Hardware and Related Software [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Total capitalized software, furniture, equipment and leasehold improvements, net of accumulated depreciation and amortization	22,051	15,702
Office Hardware [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Total capitalized software, furniture, equipment and leasehold improvements, net of accumulated depreciation and amortization	2,380	2,125
Furniture and Fixtures [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Total capitalized software, furniture, equipment and leasehold improvements, net of accumulated depreciation and amortization	1,777	1,479
Leasehold Improvements [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Total capitalized software, furniture, equipment and leasehold improvements, net of accumulated depreciation and amortization	8,129	4,709
Computer Hardware Under Capital Lease [Member]	'	'
Property, Plant and Equipment [Line Items]	'	'
Total capitalized software, furniture, equipment and leasehold improvements, net of accumulated depreciation and amortization	$1,419	$1,419

Capitalized_Software_Furniture3

Capitalized Software, Furniture, Equipment and Leasehold Improvements - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Property Plant And Equipment Useful Life And Values [Abstract]	'	'	'
Software development costs	$10.90	$5.20	$4.10
Software development costs, out-of-period adjustment	$2.90	'	'

Income_Taxes_Schedule_of_Provi

Income Taxes - Schedule of Provision for Income Taxes (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Current:	'	'	'
Federal	$26,071	$14,402	$6,187
State and local	5,958	2,287	2,849
Foreign	1,014	1,315	1,194
Total current provision	33,043	18,004	10,230
Deferred:	'	'	'
Federal	5,507	8,542	19,090
State and local	812	1,046	2,667
Foreign	-645	-6	16
Total deferred provision	5,674	9,582	21,773
Provision for income taxes	$38,717	$27,586	$32,003

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended		12 Months Ended
	Dec. 31, 2012	Mar. 31, 2011	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Schedule Of Income Taxes [Line Items]	'	'	'	'	'	'
Pre-tax income from U.S. operations	'	'	$105,200,000	$84,700,000	$77,100,000	'
U.S. federal tax at statutory rate	'	'	35.00%	35.00%	35.00%	'
Stock compensation expense	5,296,000	'	6,022,000	5,296,000	'	'
Employee and non-employee awards	'	'	48,400,000	'	'	'
Net operating loss carryforwards	'	'	700,000	'	'	'
Net operating loss carryforwards, expiration date	'	'	'2025	'	'	'
Additional annual limitations	'	'	'50% or greater change	'	'	'
Percentage of change in ownership	'	'	50.00%	'	'	'
Additional annual limitations period	'	'	'3 years	'	'	'
Tax benefit	'	4,200,000	'	'	4,237,000	11,400,000
Tax loss carryforwards	'	10,400,000	'	'	'	31,000,000
Capital loss on the sale	'	'	20,600,000	'	'	'
Capital loss carried back	'	'	1,200,000	'	'	'
Reduction in income tax provision	6,700,000	'	'	'	'	'
Decrease in unrecognized tax benefit reserve	3,600,000	'	'	'	'	'
Increase unrecognized tax benefits	3,100,000	'	'	3,100,000	'	'
Aggregate unremitted earnings	0	'	0	0	'	'
US Country [Member]	'	'	'	'	'	'
Schedule Of Income Taxes [Line Items]	'	'	'	'	'	'
Net operating loss carryforwards	'	'	9,300,000	'	'	'
Net operating loss carryforwards, expiration date	'	'	'2021	'	'	'
Foreign Country [Member]	'	'	'	'	'	'
Schedule Of Income Taxes [Line Items]	'	'	'	'	'	'
Pre-tax income from foreign operations	'	'	$2,100,000	$4,600,000	$4,400,000	'

Income_Taxes_Difference_Betwee

Income Taxes - Difference Between the Company's Reported Provision for Income Taxes and the U.S. Federal Statutory Rate (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Disclosure [Abstract]	'	'	'
U.S. federal tax at statutory rate	35.00%	35.00%	35.00%
State and local taxes-net of federal benefit	4.10%	2.40%	4.90%
Release of previously unrecognized tax benefits	'	-7.50%	'
Other, net	-3.00%	1.00%	-0.60%
Provision for income taxes	36.10%	30.90%	39.30%

Income_Taxes_Summary_of_Compan

Income Taxes - Summary of Company's Net Deferred Tax Assets (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
In Thousands, unless otherwise specified
Deferred tax assets	'	'	'	'
Capital loss carryforwards	$7,487	'	'	'
Stock compensation expense	6,022	5,296	'	'
Other	3,206	2,839	'	'
Total deferred tax assets	21,089	15,470	'	'
Valuation allowance	-7,743	-727	-287	-249
Net deferred tax assets	13,346	14,743	'	'
Deferred tax liabilities	'	'	'	'
Depreciation and amortization	-1,905	-2,025	'	'
Capitalized software development costs	-4,163	-2,752	'	'
Intangible assets	-2,331	-524	'	'
Deferred tax assets, net	4,947	9,442	'	'
US Country [Member]	'	'	'	'
Deferred tax assets	'	'	'	'
U.S net operating loss carryforwards	4,273	7,175	'	'
Foreign Country [Member]	'	'	'	'
Deferred tax assets	'	'	'	'
Foreign net operating loss carryforwards	$101	$160	'	'

Income_Taxes_Summary_of_Change

Income Taxes - Summary of Changes in Valuation Allowance (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Disclosure [Abstract]	'	'	'
Valuation allowance at beginning of year	$727	$287	$249
Current year income	-65	440	38
State net operating loss	-406	'	'
Capital loss	7,487	'	'
Valuation allowance at end of year	$7,743	$727	$287

Income_Taxes_Reconciliation_of

Income Taxes - Reconciliation of the Unrecognized Tax Benefits (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Tax Disclosure [Abstract]	'	'	'
Balance at beginning of year	$49	$3,647	$3,329
Additions for tax positions of prior years	'	'	366
Additions for tax positions of current year	235	'	'
Reductions for tax positions of prior years	-19	-3,598	-48
Balance at end of year	$265	$49	$3,647

Stockholders_Equity_Additional

Stockholders' Equity - Additional Information (Detail) (USD $)

1 Months Ended

12 Months Ended

0 Months Ended

1 Months Ended

1 Months Ended

12 Months Ended

1 Months Ended

12 Months Ended

1 Months Ended

Feb. 29, 2012

Oct. 31, 2011

Dec. 31, 2013

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2008

Dec. 27, 2012

Feb. 27, 2014

Jan. 31, 2014

Dec. 31, 2013

Dec. 31, 2012

Nov. 30, 2011

Dec. 31, 2008

Feb. 29, 2012

Dec. 31, 2012

Dec. 31, 2013

Dec. 31, 2013

Dec. 31, 2012

Jan. 31, 2011

Dec. 31, 2008

Fund

Subsequent Event [Member]

Subsequent Event [Member]

Common Stock Voting [Member]

Common Stock Voting [Member]

Warrant [Member]

Warrant [Member]

Common Stock Non-Voting [Member]

Common Stock Non-Voting [Member]

Common Stock Non-Voting [Member]

Common Stock Non-Voting [Member]

Common Stock Non-Voting [Member]

Series B Preferred Stock [Member]

Series B Preferred Stock [Member]

Class of Stock [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Common stock, shares authorized

'

'

'

'

'

'

'

'

'

110,000,000

110,000,000

'

'

'

10,000,000

10,000,000

10,000,000

10,000,000

'

'

Common stock entitles

'

'

'One

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Authorized a share repurchase program

'

$35,000,000

'

'

'

'

'

'

$35,000,000

'

'

'

'

'

'

'

'

'

'

'

Common stock shares repurchased

'

955,342

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Cost of common stock shares repurchased

'

29,200,000

'

'

6,935,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Share repurchase program expiration date

'

'

1-Jan-14

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Non-voting common stock repurchased

1,821,730

'

'

'

'

'

'

'

'

'

'

'

'

1,821,730

'

'

'

'

'

'

Cost of non-voting common stock repurchased

'

'

'

75,133,000

'

'

'

'

'

'

'

'

'

52,900,000

7,000

'

'

'

'

'

Conversion of non voting common stock to voting common stock

763,924

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Securities purchase agreement funds managed

'

'

'

'

'

2

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Series B Preferred Stock, shares authorized

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

35,000

Shares of common stock

'

'

'

'

'

'

'

'

'

'

'

'

3,500,000

'

'

'

'

'

3,499,999

'

Warrants to purchase shares, common stock

'

'

'

'

'

700,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Common stock at an exercise price

'

'

'

'

'

10

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Aggregate purchase price

'

'

'

'

'

35,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Placement agent fee and legal fees

'

'

'

'

'

33,500,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Shares conversion price

'

'

'

'

'

$10

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Closing price of the common stock

'

'

'

'

'

$17.50

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Consecutive trading days

'

'

'

'

'

'65 days

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Common stock, shares issued

'

'

'

'

'

'

'

'

'

'

'

455,465

'

'

'

'

'

'

'

'

Special dividend paid

'

'

'

'

'

'

$1.30

'

'

'

'

'

'

'

'

'

'

'

'

'

Quarterly cash dividend

'

'

$0.52

$1.74

$0.36

'

'

$0.16

'

'

'

'

'

'

'

'

'

'

'

'

StockBased_Compensation_Plans_1

Stock-Based Compensation Plans - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
	Incentive
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Number of stock incentive plans	2	'	'
Shares available for grant under the stock incentive plans	4,867,460	'	'
Options Expiration Period	'10 years	'	'
Weighted-average fair value for option granted	$19.61	$12.26	$11.29
Closing price of common stock	$66.93	'	'
Unrecognized compensation costs related to non-vested	$1.80	'	'
Weighted-average period over which cost is expected to be recognized	'2 years 6 months	'	'
Pay-out ranges, Minimum	0.00%	'	'
Pay-out ranges, Maximum	150.00%	'	'
Pay-out achievement	108.00%	92.50%	145.00%
Maximum [Member]	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Period vested for option grants	'5 years	'	'
Minimum [Member]	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Period vested for option grants	'3 years	'	'
Restricted Stock and Performance Shares [Member]	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Unrecognized compensation costs related to non-vested	$11.20	'	'
Weighted-average period over which cost is expected to be recognized	'1 year 9 months 18 days	'	'
Restricted Stock and Performance Shares [Member] | Maximum [Member]	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Period vested for option grants	'5 years	'	'
Restricted Stock and Performance Shares [Member] | Minimum [Member]	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Period vested for option grants	'3 years	'	'

StockBased_Compensation_Plans_2

Stock-Based Compensation Plans - Stock-Based Compensation Expense (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Employee [Member]	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Total stock-based compensation	$8,169	$7,714	$6,180
Employee [Member] | Restricted Stock and Performance Shares [Member]	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Total stock-based compensation	7,269	7,046	5,856
Employee [Member] | Stock Options [Member]	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Total stock-based compensation	900	668	324
Non-Employee Directors [Member]	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Total stock-based compensation	8,879	8,385	6,859
Non-Employee Directors [Member] | Restricted Stock [Member]	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Total stock-based compensation	$710	$671	$679

StockBased_Compensation_Plans_3

Stock-Based Compensation Plans - Assumptions Used for the Black-Scholes Option-Pricing Model to Determine the Per Share Weighted Average Fair Value for Options Granted (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'	'	'
Expected life (years)	'9 years 10 months 24 days	'5 years	'9 years 10 months 24 days
Risk-free interest rate	1.90%	0.70%	3.30%
Expected volatility	44.30%	48.20%	48.00%
Expected dividend yield	1.20%	1.20%	1.30%

StockBased_Compensation_Plans_4

Stock-Based Compensation Plans - Stock Option Activity (Detail) (USD $)	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'	'	'
Number of Shares, Beginning balance	1,429,822	2,927,737	4,403,562
Number of Shares, Granted	51,597	13,292	340,771
Number of Shares, Canceled	-4,348	'	-211,323
Number of Shares, Exercised	-256,622	-1,511,207	-1,605,273
Number of Shares, Ending Balance	1,220,449	1,429,822	2,927,737
Weighted Average Exercise Price, Beginning Balance	$13.62	$9.42	$9.09
Number of Shares, Exercisable	1,023,337	'	'
Weighted Average Exercise Price, Granted	$41.75	$32.45	$21.60
Weighted Average Exercise Price, Canceled	$33.84	'	$16.16
Weighted Average Exercise Price, Exercised	$12.33	$5.64	$10.21
Weighted Average Exercise Price, Ending Balance	$15.01	$13.62	$9.42
Remaining contractual term, Outstanding at December 31, 2013	'4 years	'	'
Weighted Average Exercise Price, Exercisable	$12.68	'	'
Remaining contractual term, Exercisable at December 31, 2013	'3 years 4 months 24 days	'	'
Intrinsic Value, Exercised	$10,723	'	'
Intrinsic Value, Ending Balance	63,369	'	'
Intrinsic Value, Exercisable	$55,515	'	'

StockBased_Compensation_Plans_5

Stock-Based Compensation Plans - Summary of Performance of Share Activity (Detail) (Performance Shares [Member], USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Performance Shares [Member]	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Share pay-out at plan, net of forfeitures of 14,563 for 2011	42,908	44,843	63,102
Actual share pay-out in following year	46,340	41,481	91,498
Fair value per share on grant date	$35.98	$30.64	$21.56

StockBased_Compensation_Plans_6

Stock-Based Compensation Plans - Summary of Performance of Share Activity (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2011
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'
Stock forfeitures	14,563

StockBased_Compensation_Plans_7

Stock-Based Compensation Plans - Restricted Stock and Performance Share Activity (Detail) (Restricted Stock [Member], USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Restricted Stock [Member]	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Number of Restricted Shares, Beginning balance	751,259	957,711	1,244,864	'
Number of Restricted Shares, Granted	255,266	206,965	435,548	'
Number of Restricted Shares, Performance share pay-out	41,481	91,498	130,552	'
Number of Restricted Shares, Canceled	-93,358	-7,390	-279,081	'
Number of Restricted Shares, Vested	-384,914	-497,525	-574,172	'
Number of Restricted Shares, Ending balance	569,734	751,259	957,711	'
Weighted Average Grant Date Fair Value, Beginning balance	$31.86	$21.88	$15.69	$11.23

Earnings_Per_Share_Computation

Earnings Per Share - Computation of Basic and Diluted Earnings Per Common Share (Detail) (USD $)	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]	'	'	'
Net income from continuing operations	$68,563	$61,784	$49,447
Net income (loss) from discontinued operations	-189	-1,715	-1,743
Gain on the sale of discontinued operations, net of tax benefit	7,642	'	'
Net income	$76,016	$60,069	$47,704
Basic weighted average shares outstanding	36,886	36,516	37,006
Income from continuing operations	$1.86	$1.69	$1.34
Income (loss) from discontinued operations	$0.20	($0.04)	($0.05)
Basic earnings per share	$2.06	$1.65	$1.29
Weighted average shares outstanding	36,886	36,516	37,006
Dilutive effect of stock options and restricted stock	1,002	1,300	2,602
Diluted weighted average shares outstanding	37,888	37,816	39,608
Income from continuing operations	$1.81	$1.64	$1.25
Income (loss) from discontinued operations	$0.20	($0.05)	($0.05)
Diluted earnings per share	$2.01	$1.59	$1.20
Common Stock Voting [Member]	'	'	'
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]	'	'	'
Basic weighted average shares outstanding	36,886	36,101	34,420
Weighted average shares outstanding	36,886	36,101	34,420
Common Stock Non-Voting [Member]	'	'	'
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]	'	'	'
Basic weighted average shares outstanding	'	415	2,586
Weighted average shares outstanding	'	415	2,586

Earnings_Per_Share_Additional_

Earnings Per Share - Additional Information (Detail) (Stock Options and Restricted Stock [Member])	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Stock Options and Restricted Stock [Member]	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'
Stock options and restricted stock excluded from the computation of diluted earnings per share	0.2	0.1	0.3

Credit_Facility_Additional_Inf

Credit Facility - Additional Information (Detail) (USD $)	1 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Jan. 31, 2013	Dec. 31, 2013
Line of Credit Facility [Line Items]	'	'
Revolving loans and letters of credit	$50	'
Additional Credit Facility	50	'
Amount available under credit facility	'	49.9
Period of credit agreement	'3 years	'
LIBOR rate description	'	'The federal funds effective rate plus 0.50% and (c) one month adjusted LIBOR plus 1.00% plus (ii) 0.50% or (B) the sum of (i) adjusted LIBOR plus (ii) 1.50%
Federal funds effective rate	'	0.50%
One month adjusted LIBOR	'	1.00%
LIBOR Rate	'	0.50%
Adjusted LIBOR rate	'	1.50%
Interest per annum	'	2.00%
Revolving loan commitment rate	'	0.30%
Equity interest	'	65.00%
Interest due on loan	'	$10
Maximum [Member]	'	'
Line of Credit Facility [Line Items]	'	'
Total leverage ratio	'	2.5
Minimum [Member]	'	'
Line of Credit Facility [Line Items]	'	'
Interest coverage ratio	'	3.5

Commitments_and_Contingencies_1

Commitments and Contingencies - Summary of Minimum Rental Commitments under Operating Leases (Detail) (USD $)	Dec. 31, 2013
In Thousands, unless otherwise specified
Commitments And Contingencies Disclosure [Abstract]	'
2014	$1,477
2015	1,699
2016	2,840
2017	2,764
2018 and thereafter	18,471
Operating Leases	$27,251

Commitments_and_Contingencies_2

Commitments and Contingencies - Additional Information (Detail) (USD $)	0 Months Ended	12 Months Ended
	Aug. 29, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
	sqft	Subsidiary
		Agreement
Loss Contingencies [Line Items]	'	'	'	'
Rental expense	'	$4,800,000	$2,100,000	$1,900,000
Company executed lease	16,000	'	'	'
Lease expires date	'2027-01	'	'	'
Number of lease agreements assigned to third parties	'	2	'	'
Lease termination dates	'	'November 2015 and November 2020	'	'
Future lease obligations under sublease arrangements	'	2,800,000	'	'
Possible range of loss	'	0	'	'
Number of subsidiaries	'	2	'	'
Settlement days of bond transaction	'	'Within one to three trading days	'	'
Revenues from riskless principal trading	'	6,000,000	'	'
Collateral deposit	'	900,000	'	'
Standby Letters of Credit [Member]	'	'	'	'
Loss Contingencies [Line Items]	'	'	'	'
Contingent obligation for standby letter of credit issued to Landlord	'	$1,300,000	'	'

Sale_of_Discontinued_Operation2

Sale of Discontinued Operations - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013
Discontinued Operations And Disposal Groups [Abstract]	'	'
Recognized gain, net of tax	$7,642,000	'
Stock purchase agreement	'	100.00%
Aggregate purchase price	'	$11,000,000

Sale_of_Discontinued_Operation3

Sale of Discontinued Operations - Summary of Greenline's Operating Results (Detail) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]	'	'	'
Gain on the sale of discontinued operations, net of tax benefit	$7,642	'	'
Income (loss) from discontinued operations	-189	-1,715	-1,743
Discontinued Operations [Member]	'	'	'
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]	'	'	'
Revenues	6,137	7,364	9,227
Expenses	6,384	10,048	11,944
Loss before income taxes and gain on the sale from discontinued operations	-247	-2,684	-2,717
Benefit for income taxes	-58	-969	-974
Gain on the sale of discontinued operations, net of tax benefit	7,642	'	'
Income (loss) from discontinued operations	$7,453	($1,715)	($1,743)

Related_Party_Additional_Infor

Related Party - Additional Information (Detail) (USD $)	1 Months Ended	2 Months Ended	12 Months Ended
In Millions, except Share data, unless otherwise specified	Feb. 29, 2012	Feb. 28, 2012	Dec. 31, 2011
Statement Of Partners Capital [Abstract]	'	'	'
Public offering common stock shares	3,597,333	'	'
Non-voting common stock repurchased	1,821,730	'	'
Revenue generated by related party	'	$1.60	$7.50

Retirement_Savings_Plans_Addit

Retirement Savings Plans - Additional Information (Detail) (USD $)	12 Months Ended
In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Compensation And Retirement Disclosure [Abstract]	'	'	'
Contribution to defined plans	$0.80	$0.70	$0.70

Customer_Concentration_Additio

Customer Concentration - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
	Customer	Customer	Customer
Risks And Uncertainties [Abstract]	'	'	'
Number of client accounted for total revenue	0	0	0
Total revenue, accounted for single client	'More than 10%	'More than 10%	'More than 10%
Percentage of trading volumes by single client	12.50%	13.50%	14.60%
Percentage of outstanding shares owned by single client	9.00%	'	'