Impact of Adjustments to Redeemable Non-controlling Interest on Earnings Per Share Calculation (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Earnings Per Share [Abstract]
Net loss from continuing operations attributable to Iconix Brand Group, Inc.	$ (550,571)	$ 14,180	$ (559,707)	$ 39,407
Accretion of redeemable non-controlling interest	(547)		(1,641)
Net loss attributable to Iconix Brand Group, Inc. after accretion of redeemable non-controlling interest	(551,118)		(561,348)
Net income (loss) from discontinued operations attributable to Iconix Brand Group, Inc.	(2,130)	$ 1,036	46,369	$ 6,005
Net (loss) income attributable to Iconix Brand Group, Inc.	$ (553,248)		$ (514,979)
(Loss) earnings per share - basic:
Continuing operations	$ (9.64)	$ 0.26	$ (9.83)	$ 0.77
Discontinued operations	(0.04)	0.02	0.81	0.12
(Loss) earnings per share - basic	(9.67)	0.27	(9.02)	0.89
(Loss) earnings per share - diluted:
Continuing operations	(9.64)	0.25	(9.83)	0.75
Discontinued operations	(0.04)	0.02	0.81	0.11
(Loss) earnings per share - diluted	$ (9.67)	$ 0.27	$ (9.02)	$ 0.86
Weighted average number of common shares outstanding:
Basic	57,189	55,584	57,081	51,060
Diluted	57,189	57,355	57,081	52,802