Consolidated Financial Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Licensing revenue	$ 87,142	$ 90,944	$ 95,743	$ 94,632	$ 94,653	$ 91,332	$ 97,398	$ 95,814	$ 368,461	$ 379,197	$ 391,490
Operating income (loss), net	(385,811)	40,663	47,811	54,209	(398,245)	27,782	51,824	55,976	(243,128)	(262,663)	220,428
Provision (benefit) for income taxes	(104,723)	9,931	7,692	10,608	(140,427)	6,275	11,536	27,272	(76,492)	(95,344)	48,288
Net (loss) income	(309,503)	19,799	17,074	23,121	(275,976)	(954)	18,955	69,045	(249,509)	(188,930)	118,822
Net income (loss) attributable to Iconix Brand Group, Inc.	$ (297,548)	$ 15,216	$ 11,582	$ 18,616	$ (263,014)	$ (5,387)	$ 13,739	$ 65,359	$ (252,134)	$ (189,303)	$ 103,723
Basic earnings per share	$ (5.30)	$ 0.27	$ 0.24	$ 0.38	$ (5.44)	$ (0.11)	$ 0.28	$ 1.36	$ (4.82)	$ (3.92)	$ 2.14
Diluted earnings per share	$ (5.30)	$ 0.27	$ 0.23	$ 0.37	$ (5.44)	$ (0.11)	$ 0.28	$ 1.26	$ (4.82)	$ (3.92)	$ 1.81
Comprehensive income (loss)	$ (324,814)	$ 22,846	$ 9,299	$ 33,625	$ (286,413)	$ 3,097	$ 26,370	$ 31,309	$ (259,044)	$ (225,637)	$ 78,150
Comprehensive income (loss) attributable to Iconix Brand Group, Inc.	$ (312,859)	$ 18,263	$ 3,807	$ 29,120	$ (273,451)	$ (1,336)	$ 21,155	$ 27,622	$ (261,669)	$ (226,010)	$ 63,051