Unaudited Interim Consolidated Financial Information (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Quarterly Financial Information [Line Items]
Licensing and other revenue	$ 85,131	$ 86,590	$ 93,646	$ 88,451	$ 95,513	$ 92,683	$ 89,293	$ 92,356	$ 353,818	$ 369,845	$ 332,559
Operating income	45,329	53,564	59,005	57,552	51,922	58,954	57,586	60,304	215,450	228,766	209,715
Net income attributable to Iconix Brand Group, Inc.	$ 26,093	$ 27,131	$ 28,585	$ 27,599	$ 27,162	$ 25,968	$ 41,543	$ 31,432	$ 109,408	$ 126,105	$ 98,847
Basic earnings per share	$ 0.38	$ 0.40	$ 0.41	$ 0.38	$ 0.37	$ 0.35	$ 0.57	$ 0.43	$ 1.57	$ 1.72	$ 1.37
Diluted earnings per share	$ 0.37	$ 0.38	$ 0.40	$ 0.37	$ 0.36	$ 0.34	$ 0.55	$ 0.42	$ 1.52	$ 1.67	$ 1.32