Document and Entity Information - shares
3 Months Ended
Apr. 30, 2018
Jun. 01, 2018
Document And Entity Information Abstract    
Entity Registrant Name G III APPAREL GROUP LTD /DE/  
Entity Central Index Key 0000821002  
Trading Symbol giii  
Current Fiscal Year End Date --01-31  
Entity Filer Category Large Accelerated Filer  
Entity Common Stock Shares Outstanding   49,169,042
Document Type 10-Q  
Document Period End Date Apr. 30, 2018  
Amendment Flag false  
Document Fiscal Year Focus 2019  
Document Fiscal Period Focus Q1