Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2023	Jul. 24, 2023
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q2
Trading Symbol	MKTX
Entity Registrant Name	MARKETAXESS HOLDINGS INC.
Entity Central Index Key	0001278021
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false
Title of 12(b) Security	Common Stock, $0.003 par value
Security Exchange Name	NASDAQ
Entity File Number	001-34091
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	52-2230784
Entity Address, Address Line One	55 Hudson Yards
Entity Address, Address Line Two	15th Floor
Entity Address, City or Town	New York
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10001
Document Quarterly Report	true
Document Transition Report	false
City Area Code	212
Local Phone Number	813-6000
Entity Common Stock, Shares Outstanding		37,677,426