Document and Entity Information - shares	6 Months Ended
	Jul. 31, 2019	Sep. 03, 2019
Document And Entity Information Abstract
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jul. 31, 2019
Document Transition Report	false
Entity File Number	0-18183
Entity Registrant Name	G III APPAREL GROUP LTD /DE/
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	41-1590959
Entity Address, Address Line One	512 Seventh Avenue
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	403-0500
Title of 12(b) Security	Common Stock
Trading Symbol	GIII
Security Exchange Name	The Nasdaq Stock Market
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock Shares Outstanding		47,745,045
Entity Central Index Key	0000821002
Current Fiscal Year End Date	--01-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2
Amendment Flag	false