Net Income per Common Share - Reconciliation between basic and diluted net income per share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jul. 31, 2014	Jul. 31, 2013	Jul. 31, 2014	Jul. 31, 2013
Earnings Per Share [Abstract]
Net income attributable to G-III	$ 6,236	$ 3,592	$ 7,526	$ 4,710
Basic net income per share:
Basic common shares	21,187	20,305	20,843	20,234
Basic net income per share (in dollars per share)	$ 0.29	$ 0.18	$ 0.36	$ 0.23
Diluted net income per share:
Basic common shares	21,187	20,305	20,843	20,234
Restricted stock awards and stock options	473	448	503	452
Diluted common shares	21,660	20,753	21,346	20,686
Diluted net income per share (in dollars per share)	$ 0.29	$ 0.17	$ 0.35	$ 0.23