Net Capital Requirements and Customer Protection Requirements - Net Capital Requirements and Customer Protection Requirements (Detail) (USD $)	Jun. 30, 2013
Adjusted Capital Requirements And Customer Protection Requirements [Line Items]
Minimum net capital required	$ 100,000
MarketAxess Corporation [Member]
Adjusted Capital Requirements And Customer Protection Requirements [Line Items]
Net capital	45,779,000
Minimum net capital required	2,028,000
Excess net capital	43,751,000
MarketAxess Europe Limited [Member]
Adjusted Capital Requirements And Customer Protection Requirements [Line Items]
Net capital	16,345,000
Minimum net capital required	3,190,000
Excess net capital	13,155,000
MarketAxess Canada Limited [Member]
Adjusted Capital Requirements And Customer Protection Requirements [Line Items]
Net capital	426,000
Minimum net capital required	262,000
Excess net capital	$ 164,000