Document and Entity Information - USD ($)	12 Months Ended
	Jan. 31, 2018	Apr. 02, 2018	Jul. 31, 2017
Document And Entity Information Abstract
Entity Registrant Name	G III APPAREL GROUP LTD /DE/
Entity Central Index Key	0000821002
Trading Symbol	giii
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Current Fiscal Year End Date	--01-31
Entity Filer Category	Large Accelerated Filer
Entity Well-known Seasoned Issuer	Yes
Entity Common Stock Shares Outstanding		49,145,809
Entity Public Float			$ 1,156,454,072
Document Type	10-K
Document Period End Date	Jan. 31, 2018
Amendment Flag	false
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY