Parent Company Information - Condensed Statements of Cash Flows (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Cash flows from operating activities
Net income	$ 250,224	$ 257,888	$ 299,377
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	61,446	53,447	35,996
Amortization of operating lease right-of-use assets	5,708	6,799	6,842
Stock-based compensation expense	29,864	27,314	25,613
Deferred taxes	(6,547)	3,118	10,099
Other	555	(466)	(550)
Changes in operating assets and liabilities:
(Increase) decrease in accounts receivable	(15,136)	15,598	(18,015)
(Increase) in prepaid expenses and other assets	(4,249)	2,214	(1,977)
(Decrease) increase in accrued employee compensation	(3,417)	(2,607)	14,961
Increase (decrease) in income and other tax liabilities	(4,768)	(5,638)	16,189
Increase (decrease) in accounts payable, accrued expenses and other liabilities	11,384	215	6,006
(Decrease) in operating lease liabilities	(6,373)	(7,001)	(5,788)
Net cash provided by operating activities	289,231	282,091	404,489
Cash flows from investing activities
Acquisitions, net of cash and cash equivalents acquired	0	(17,078)	(23,297)
Acquisition of equity method investment	(34,400)	0	0
Proceeds from maturities and sales	0	0	170,657
Purchases	0	0	(32,865)
Purchases of furniture, equipment and leasehold improvements	(13,142)	(17,493)	(15,010)
Net cash (used in) provided by investing activities	(86,272)	(67,694)	68,867
Cash flows from financing activities
Cash dividend on common stock	(105,942)	(99,792)	(90,566)
Exercise of stock options	672	7,096	4,007
Withholding tax payments on restricted stock vesting and stock option exercises	(23,404)	(33,890)	(42,418)
Repurchases of common stock	(87,540)	(63,189)	(16,135)
Proceeds from short-term borrowings	100,000	70,348	578,356
Repayments of short-term borrowings	(100,000)	(70,348)	(578,356)
Net cash (used in) financing activities	(242,378)	(189,775)	(145,112)
Effect of exchange rate changes on investments	(13,484)	(7,105)	5,553
Cash and cash equivalents including restricted cash
Net increase (decrease) for the period	(52,903)	17,517	333,797
Beginning of period	625,567	608,050	274,253
End of period	572,664	625,567	608,050
Supplemental cash flow information:
Cash paid for income taxes	88,677	70,003	45,046
Cash paid for interest	652	830	1,142
Non-cash investing and financing activity:
Exercise of stock options - cashless	3,845	2,750	10,866
MarketAxess Holdings Inc. (Parent) [Member]
Cash flows from operating activities
Net income	250,224	257,888	299,377
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	2,136	2,123	2,068
Amortization of operating lease right-of-use assets	3,347	4,484	4,117
Stock-based compensation expense	12,554	12,706	10,834
Deferred taxes	(5,076)	1,712	3,644
Equity in undistributed income of subsidiaries	(15,220)	(111,945)	(276,090)
Other	(441)	0	(671)
Changes in operating assets and liabilities:
(Increase) decrease in accounts receivable	(769)	178	(115)
Decrease (increase) in receivable from subsidiaries	(7,931)	(47,371)	25,049
(Increase) in prepaid expenses and other assets	(1,175)	(219)	(1,085)
(Increase) decrease in income and other tax receivables	(9,711)	7,265	(1,240)
(Decrease) increase in accrued employee compensation	(1,372)	824	3,698
Increase (decrease) in income and other tax liabilities	62	(143)	6,676
Increase (decrease) in accounts payable, accrued expenses and other liabilities	443	(607)	(442)
(Decrease) in operating lease liabilities	(3,689)	(4,673)	(4,055)
Net cash provided by operating activities	241,110	215,449	20,339
Cash flows from investing activities
Acquisitions, net of cash and cash equivalents acquired	0	(17,079)
Acquisition of equity method investment	(34,400)	0	0
Investments in subsidiaries	(8,326)
Proceeds from maturities and sales			170,657
Purchases			(32,865)
Purchases of furniture, equipment and leasehold improvements	(96)	(198)	(337)
Net cash (used in) provided by investing activities	(42,822)	(17,277)	137,455
Cash flows from financing activities
Cash dividend on common stock	(105,942)	(99,791)	(90,566)
Exercise of stock options	672	7,096	4,007
Withholding tax payments on restricted stock vesting and stock option exercises	(23,404)	(33,890)	(42,418)
Repurchases of common stock	(87,540)	(63,189)	(16,135)
Proceeds from short-term borrowings	100,000		348,000
Repayments of short-term borrowings	100,000		(348,000)
Net cash (used in) financing activities	(216,214)	(189,774)	(145,112)
Effect of exchange rate changes on investments	15	(2,324)	(5,176)
Cash and cash equivalents including restricted cash
Net increase (decrease) for the period	(17,911)	6,073	7,506
Beginning of period	61,820	55,747	48,241
End of period	43,909	61,820	55,747
Supplemental cash flow information:
Cash paid for income taxes	65,764	41,103	32,674
Cash paid for interest	271		805
Non-cash investing and financing activity:
Exercise of stock options - cashless	3,845	2,750	10,866
Mutual Funds Held In Rabbi Trust [Member]
Changes in operating assets and liabilities:
(Increase) decrease in trading investments	1,813	(2,306)	(2,671)
Mutual Funds Held In Rabbi Trust [Member] | MarketAxess Holdings Inc. (Parent) [Member]
Changes in operating assets and liabilities:
(Increase) decrease in trading investments	$ 984	$ (1,516)	$ (1,328)