Organization and Basis of Presentation - Additional Information (Detail) $ / shares in Units, $ in Thousands			3 Months Ended	12 Months Ended
	Apr. 28, 2015 USD ($) $ / shares shares	Feb. 26, 2015 Clients $ / shares shares	Mar. 31, 2015 shares	Dec. 31, 2015 USD ($) Segments shares	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Jan. 12, 2016 $ / shares
Description Of Business [Line Items]
Number of servicing segments | Segments				2
Tendered shares owned | shares		17,100,000
Stock issued during period, value, new issues | $				$ 1,108	$ 361	$ 6,009
GFI Group Inc. [Member]
Description Of Business [Line Items]
Business acquisition date				Feb. 26, 2015
Common stock, par value | $ / shares		$ 6.10
Tendered shares purchased | shares		54,300,000
Percentage of outstanding common stock owned by parent	67.00%	56.00%		100.00%
Tendered shares owned | shares			17,100,000	17,100,000
Stock issued during period, shares, new issues | shares	43,000,000
Closing price per share | $ / shares	$ 5.81
Stock issued during period, value, new issues | $	$ 250,000
Senior Notes maturity date				Jun. 19, 2018
Debt instrument, description of reference rate				LIBOR
Debt instrument, basis point	2.00%
Number of institutional clients | Clients		2,500
Number of offices		50
GFI Group Inc. [Member] | Subsequent Event [Member]
Description Of Business [Line Items]
Common stock, par value | $ / shares							$ 6.10
Percentage of outstanding common stock owned by parent							33.00%
Ownership percentage owned by parent company and its affiliates							100.00%
Jersey Partners, Inc. [Member]
Description Of Business [Line Items]
Business acquisition date				Dec. 22, 2015
Common Stock [Member] | GFI Group Inc. [Member]
Description Of Business [Line Items]
Common stock, par value | $ / shares		$ 0.01