Goodwill and Trademarks and Other Intangibles, net - Additional Information (Detail)	1 Months Ended						3 Months Ended				9 Months Ended	12 Months Ended
	Jul. 31, 2017 USD ($)	Jun. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2015 USD ($)	Feb. 28, 2015 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2017	Dec. 31, 2017 USD ($) Segment	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Intangible Assets by Major Class [Line Items]
Changes in goodwill		$ (53,000,000)
Number of reportable segments | Segment												4
Non-cash impairment charge							$ 0	$ 103,900,000	$ 18,300,000	$ 35,100,000		$ 103,877,000	$ 18,331,000	$ 35,132,000
Impairment of intangible assets, indefinite-lived							4,100,000	$ 521,700,000	419,800,000	$ 402,400,000		525,726,000	419,762,000	402,392,000
Amortization expense for intangible assets												741,000	1,327,000	$ 2,755,000
Projects amortization expenses, 2018							300,000					300,000
Projects amortization expenses, 2019							100,000					100,000
Projects amortization expenses, 2020							0					0
Projects amortization expenses, 2021							0					0
Projects amortization expenses, 2022							0					$ 0
Iconix China
Intangible Assets by Major Class [Line Items]
Controlling interest					50.00%
Interest acquired, including previously acquired interest					100.00%					100.00%				100.00%
Strawberry Shortcake
Intangible Assets by Major Class [Line Items]
Increase in value of indefinite-lived trademarks and licensing contracts					$ 56,200,000
Pony International, LLC.
Intangible Assets by Major Class [Line Items]
Controlling interest						75.00%
Increase in value of indefinite-lived trademarks and licensing contracts						$ 32,600,000
Non-controlling interest						25.00%
Iconix SE Asia, Ltd.
Intangible Assets by Major Class [Line Items]
Increase (Decrease) in indefinite-lived trademarks		(22,700,000)
Minimum
Intangible Assets by Major Class [Line Items]
Finite-lived intangible assets, useful life												1 year
Maximum
Intangible Assets by Major Class [Line Items]
Finite-lived intangible assets, useful life												15 years
Trademarks
Intangible Assets by Major Class [Line Items]
Residual value							0					$ 0
Increase (Decrease) in indefinite-lived trademarks		(204,300,000)
Trademarks | Iconix China
Intangible Assets by Major Class [Line Items]
Increase in value of indefinite-lived intangible assets					$ 40,500,000
Trademarks | NGX, LLC
Intangible Assets by Major Class [Line Items]
Increase (Decrease) in indefinite-lived trademarks	$ (5,000,000)
Trademarks | Peanuts Holdings, LLC
Intangible Assets by Major Class [Line Items]
Increase (Decrease) in indefinite-lived trademarks		(153,600,000)
Trademarks | Strawberry Shortcake
Intangible Assets by Major Class [Line Items]
Increase (Decrease) in indefinite-lived trademarks		(50,700,000)
Trademarks | Sharper Image intellectual property and related assets
Intangible Assets by Major Class [Line Items]
Increase (Decrease) in indefinite-lived trademarks			$ (55,600,000)
Trademarks | London Fog Korea trademark
Intangible Assets by Major Class [Line Items]
Increase (Decrease) in indefinite-lived trademarks				$ (400,000)
Trademarks | Minimum
Intangible Assets by Major Class [Line Items]
Finite-lived intangible assets, useful life												10 years
Residual value							0					$ 0
Trademarks | Maximum
Intangible Assets by Major Class [Line Items]
Finite-lived intangible assets, useful life												15 years
Residual value							0					$ 0
Trademarks | Assets Held for Sale
Intangible Assets by Major Class [Line Items]
Increase (Decrease) in indefinite-lived trademarks												(204,300,000)
Trademarks | Assets Held for Sale | Peanuts Holdings, LLC
Intangible Assets by Major Class [Line Items]
Increase (Decrease) in indefinite-lived trademarks												(153,600,000)
Trademarks | Assets Held for Sale | Strawberry Shortcake
Intangible Assets by Major Class [Line Items]
Increase (Decrease) in indefinite-lived trademarks												$ (50,700,000)
Mossimo License Agreement | Target
Intangible Assets by Major Class [Line Items]
License agreement expiration date											2018-10
DanskinNow License Agreement | Walmart
Intangible Assets by Major Class [Line Items]
License agreement expiration date											2019-01
Non-compete agreements and contracts | Minimum
Intangible Assets by Major Class [Line Items]
Finite-lived intangible assets, useful life												1 year
Residual value							0					$ 0
Non-compete agreements and contracts | Maximum
Intangible Assets by Major Class [Line Items]
Finite-lived intangible assets, useful life												15 years
Residual value							$ 0					$ 0
Operating Segments | Trademarks
Intangible Assets by Major Class [Line Items]
Impairment of intangible assets, indefinite-lived										$ 402,400,000		521,800,000
Operating Segments | Trademarks | Discontinued Operations
Intangible Assets by Major Class [Line Items]
Impairment of intangible assets, indefinite-lived									424,900,000
Home
Intangible Assets by Major Class [Line Items]
Non-cash impairment charge									0	0
Home | Operating Segments
Intangible Assets by Major Class [Line Items]
Non-cash impairment charge												28,414,000
Home | Operating Segments | Trademarks
Intangible Assets by Major Class [Line Items]
Impairment of intangible assets, indefinite-lived										37,800,000		69,500,000
Home | Operating Segments | Trademarks | Discontinued Operations
Intangible Assets by Major Class [Line Items]
Impairment of intangible assets, indefinite-lived									50,000,000
Women's
Intangible Assets by Major Class [Line Items]
Non-cash impairment charge									0	0
Women's | Operating Segments
Intangible Assets by Major Class [Line Items]
Non-cash impairment charge												73,939,000
Women's | Operating Segments | Trademarks
Intangible Assets by Major Class [Line Items]
Impairment of intangible assets, indefinite-lived										2,200,000		227,600,000
Women's | Operating Segments | Trademarks | Discontinued Operations
Intangible Assets by Major Class [Line Items]
Impairment of intangible assets, indefinite-lived									31,500,000
Men's
Intangible Assets by Major Class [Line Items]
Non-cash impairment charge									18,300,000
Men's | Operating Segments
Intangible Assets by Major Class [Line Items]
Non-cash impairment charge												1,524,000	18,331,000
Men's | Operating Segments | Trademarks
Intangible Assets by Major Class [Line Items]
Impairment of intangible assets, indefinite-lived										327,800,000		135,900,000
Men's | Operating Segments | Trademarks | Discontinued Operations
Intangible Assets by Major Class [Line Items]
Impairment of intangible assets, indefinite-lived									144,600,000
Entertainment
Intangible Assets by Major Class [Line Items]
Non-cash impairment charge									0	0
Entertainment | Operating Segments | Trademarks | Discontinued Operations
Intangible Assets by Major Class [Line Items]
Impairment of intangible assets, indefinite-lived									5,100,000
International
Intangible Assets by Major Class [Line Items]
Non-cash impairment charge									0
International | Operating Segments | Trademarks
Intangible Assets by Major Class [Line Items]
Impairment of intangible assets, indefinite-lived									193,700,000	$ 34,600,000		$ 88,800,000
Iconix SE Asia, Ltd. | Global Brand Group Asia, Ltd.
Intangible Assets by Major Class [Line Items]
Changes in goodwill		$ (3,500,000)
Sharper Image Brand | Home
Intangible Assets by Major Class [Line Items]
Goodwill			$ 14,500,000						$ 14,500,000				$ 14,500,000