Parent Company Information - Condensed Statements of Financial Condition (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
ASSETS
Cash and cash equivalents	$ 451,280	$ 430,746
Investments, at fair value	134,861	83,792
Accounts receivable	89,839	78,450
Intangible assets, net of accumulated amortization	119,108	98,065
Furniture, equipment, leasehold improvements and capitalized software, net of accumulated depreciation and amortization	102,671	100,256
Operating lease right-of-use assets	63,045	66,106
Prepaid expenses and other assets	84,499	68,289
Total assets	2,015,067	1,607,775
Liabilities
Accrued employee compensation	60,124	56,302
Income and other tax liabilities	7,892	28,448
Accounts payable, accrued expenses and other liabilities	37,013	55,263
Operating lease liabilities	79,677	82,676
Total liabilities	722,104	526,682
Stockholders' equity
Preferred stock	0	0
Common stock voting	123	123
Additional paid-in capital	333,292	345,468
Treasury stock	260,298	328,326
Retained earnings	1,244,216	1,101,525
Accumulated other comprehensive loss	(24,370)	(37,697)
Total stockholders' equity	1,292,963	1,081,093	$ 1,041,309	$ 955,061
Total liabilities and stockholders' equity	2,015,067	1,607,775
MarketAxess Holdings Inc. (Parent) [Member]
ASSETS
Cash and cash equivalents	65,951	43,909
Investments, at fair value	30,225	5,343
Accounts receivable	1,923	769
Receivable from subsidiaries	18,010	8,962
Intangible assets, net of accumulated amortization	21	23
Furniture, equipment, leasehold improvements and capitalized software, net of accumulated depreciation and amortization	17,644	19,557
Operating lease right-of-use assets	55,113	57,402
Investments in subsidiaries	1,140,798	985,222
Prepaid expenses and other assets	45,140	41,511
Income and other tax receivable	7,674	11,474
Total assets	1,382,499	1,174,172
Liabilities
Accrued employee compensation	8,589	9,693
Income and other tax liabilities	3,000	12
Accounts payable, accrued expenses and other liabilities	8,212	11,087
Operating lease liabilities	69,735	72,287
Total liabilities	89,536	93,079
Stockholders' equity
Preferred stock	0	0
Common stock voting	123	123
Additional paid-in capital	333,292	345,468
Treasury stock	(260,298)	(328,326)
Retained earnings	1,244,216	1,101,525
Accumulated other comprehensive loss	(24,370)	(37,697)
Total stockholders' equity	1,292,963	1,081,093
Total liabilities and stockholders' equity	1,382,499	1,174,172
Series A Preferred Stock [Member]
Stockholders' equity
Preferred stock	0	0
Series A Preferred Stock [Member] | MarketAxess Holdings Inc. (Parent) [Member]
Stockholders' equity
Preferred stock	$ 0	$ 0