Parent Company Information - Condensed Statements of Financial Condition (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
ASSETS
Cash and cash equivalents	$ 430,746	$ 506,735
Investments, at fair value	83,792	36,078
Accounts receivable	78,450	63,881
Intangible assets, net of accumulated amortization	98,065	116,377
Furniture, equipment, leasehold improvements and capitalized software, net of accumulated depreciation and amortization	100,256	96,061
Operating lease right-of-use assets	66,106	70,960
Prepaid expenses and other assets	68,289	27,066
Total assets	1,607,775	1,530,452
Liabilities
Accrued employee compensation	56,302	59,719
Income and other tax liabilities	28,448	40,456
Accounts payable, accrued expenses and other liabilities	55,263	71,218
Operating lease liabilities	82,676	88,425
Total liabilities	526,682	489,143
Stockholders' equity
Preferred stock	0	0
Common stock	123	123
Additional paid-in capital	345,468	330,262
Treasury stock	328,326	232,712
Retained earnings	1,101,525	956,966
Accumulated other comprehensive loss	(37,697)	(13,330)
Total stockholders' equity	1,081,093	1,041,309	$ 955,061	$ 770,091
Total liabilities and stockholders' equity	1,607,775	1,530,452
MarketAxess Holdings Inc. (Parent) [Member]
ASSETS
Cash and cash equivalents	43,909	61,820
Investments, at fair value	5,343	6,327
Accounts receivable	769	0
Receivable from subsidiaries	8,962	3,488
Intangible assets, net of accumulated amortization	23	25
Furniture, equipment, leasehold improvements and capitalized software, net of accumulated depreciation and amortization	19,557	21,596
Operating lease right-of-use assets	57,402	60,753
Investments in subsidiaries	985,222	982,029
Prepaid expenses and other assets	41,511	4,810
Income and other tax receivable	11,474	1,763
Total assets	1,174,172	1,142,611
Liabilities
Accrued employee compensation	9,693	11,065
Income and other tax liabilities	12	5,026
Accounts payable, accrued expenses and other liabilities	11,087	9,233
Operating lease liabilities	72,287	75,978
Total liabilities	93,079	101,302
Stockholders' equity
Preferred stock	0	0
Common stock	123	123
Additional paid-in capital	345,468	330,262
Treasury stock	(328,326)	(232,712)
Retained earnings	1,101,525	956,966
Accumulated other comprehensive loss	(37,697)	(13,330)
Total stockholders' equity	1,081,093	1,041,309
Total liabilities and stockholders' equity	1,174,172	1,142,611
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