Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2018	Nov. 19, 2018
Document And Entity Information [Abstract]
Document Type	10-Q/A
Amendment Flag	true
Amendment Description	Iconix Brand Group, Inc. (“the Company”) is filing this Amendment No. 1 on Form 10-Q/A (the “Amended Filing”) to amend its Quarterly Report on Form 10-Q for the quarter ended March 31, 2018, originally filed with the U.S. Securities and Exchange Commission (the “SEC”) on May 10, 2018 (the “Original Filing”). Background and Effects of the RestatementAs previously disclosed, subsequent to the issuance of the Original Filing, Iconix determined that the calculation of diluted earnings per share included therein did not reflect the dilutive impact of the potential conversion of the Company’s 5.75% convertible senior subordinated notes due August 2023 (the “5.75% Convertible Notes”). In accordance with Accounting Standards Codification 260, “Earnings Per Share,” when calculating diluted earnings per share, the dilutive effect of convertible securities shall be reflected as an adjustment to the income available to common stockholders and as an adjustment to the weighted average shares outstanding. This adjustment for the convertible securities is required when the net effect of the adjustment is dilutive to the Company’s earnings per share. For the three months ended March 31, 2018, diluted earnings per share was restated from the previously reported diluted earnings per share of $0.51 to a restated diluted earnings per share of $0.11. Additionally, during the six months ended June 30, 2018, the Company determined that the debt issuance costs associated with the Company’s issuance of its 5.75% Convertible Notes had been incorrectly capitalized in the Company’s consolidated balance sheet as of March 31, 2018. Management evaluated the materiality of the error from a quantitative and qualitative perspective and concluded that this adjustment was not material to the Company’s presentation and disclosures, and had no material impact on the Company’s financial position, results of operations and cash flows. Accordingly, no amendment to the previously filed report was deemed necessary at that time. However, the Company has corrected this adjustment in this Amended Filing. Refer to Note 1 of the Notes to Unaudited Condensed Consolidated Financial Statements in this Amended Filing.Disclosure Controls and ProceduresManagement has reassessed its evaluation of the effectiveness of its Disclosure Controls and Procedures as of March 31, 2018, and has concluded that there was a previously identified material weakness in Iconix’s management review controls related to the financial reporting for the modification of our debt. For a description of the material weakness in our internal control over financial reporting and our plan to remediate the material weakness, see Part II – Item 4. Controls and Procedures of this Amended Filing. Items Amended in This FilingThis Amended Filing amends and restates the following items of the Company’s Original Filing as of, and for the period ended March 31, 2018.Part I – Item 1. Financial StatementsPart II – Item 6. ExhibitsIn accordance with applicable SEC rules, this Amended Filing includes certifications as required by Rule 12b-15 under the Securities Exchange Act of 1934, as amended (the “Exchange Act”) from the Company’s Principal Executive Officer and Principal Financial Officer dated as of the date of this Amended Filing.Except for the items noted above, no other information included in the Original Filing is being amended by this Amended Filing. The Amended Filing speaks as of the date of the Original Filing and the Company has not updated the Original Filing to reflect events occurring subsequent to the date of the Original Filing. Accordingly, this Amended Filing should be read in conjunction with the Company’s filings made with the SEC subsequent to the date of the Original Filing.
Document Period End Date	Mar. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q1
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	Accelerated Filer
Entity Common Stock, Shares Outstanding		75,192,597