SIGNIFICANT ACCOUNTING POLICIES - Reconciliation between Basic and Diluted Net Income per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Jan. 31, 2016	Oct. 31, 2015	Jul. 31, 2015	Apr. 30, 2015	Jan. 31, 2015	Oct. 31, 2014	Jul. 31, 2014	Apr. 30, 2014	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014
Accounting Policies [Abstract]
Net income attributable to G-III (in dollars)	$ 7,964	$ 87,156	$ 12,453	$ 6,760	$ 22,220	$ 80,615	$ 6,236	$ 1,290	$ 114,333	$ 110,361	$ 77,360
Basic net income per share:
Basic common shares									45,328	43,298	40,646
Basic net income per share	$ 0.17	$ 1.92	$ 0.28	$ 0.15	$ 0.49	$ 1.80	$ 0.15	$ 0.03	$ 2.52	$ 2.55	$ 1.90
Diluted net income per share:
Basic common shares									45,328	43,298	40,646
Stock options and restricted stock awards									1,184	1,126	1,082
Diluted common shares									46,512	44,424	41,728
Diluted net income per share	$ 0.17	$ 1.87	$ 0.27	$ 0.15	$ 0.48	$ 1.76	$ 0.14	$ 0.03	$ 2.46	$ 2.48	$ 1.85