Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2020	Nov. 07, 2020
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Trading Symbol	ICON
Entity Registrant Name	ICONIX BRAND GROUP, INC.
Entity Central Index Key	0000857737
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity Emerging Growth Company	false
Entity File Number	1-10593
Entity Tax Identification Number	11-2481903
Entity Address, Address Line One	1450 Broadway
Entity Address, City or Town	New York
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10018
City Area Code	212
Local Phone Number	730-0030
Entity Common Stock, Shares Outstanding		13,174,848
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common Stock, $0.001 par value
Security Exchange Name	NASDAQ
Entity Incorporation, State or Country Code	DE
Document Quarterly Report	true
Document Transition Report	false