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
	Mar. 31, 2017	Mar. 31, 2016
Earnings Per Share [Abstract]
Net income from continuing operations attributable to Iconix Brand Group, Inc.	$ 4,402	$ 14,629
Accretion of redeemable non-controlling interest	(1,026)
Net income attributable to Iconix Brand Group, Inc. after accretion of redeemable non-controlling interest	3,376
Net income (loss) from discontinued operations attributable to Iconix Brand Group, Inc.	(8,682)	$ 3,987
Net income (loss) attributable to Iconix Brand Group, Inc.	$ (5,306)
Earnings (loss) per share - basic:
Continuing operations	$ 0.06	$ 0.30
Discontinued operations	(0.15)	0.08
Earnings (loss) per share - basic	(0.09)	0.38
Earnings (loss) per share - diluted:
Continuing operations	0.06	0.29
Discontinued operations	(0.15)	0.08
Earnings (loss) per share - diluted	$ (0.09)	$ 0.37
Weighted average number of common shares outstanding:
Basic	56,964	48,509
Diluted	56,964	50,327