QUARTERLY FINANCIAL DATA (UNAUDITED) (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Jan. 31, 2017	Oct. 31, 2016	Jul. 31, 2016	Apr. 30, 2016	Jan. 31, 2016	Oct. 31, 2015	Jul. 31, 2015	Apr. 30, 2015	Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 603,289	$ 883,476	$ 442,267	$ 457,403	$ 527,428	$ 909,865	$ 473,884	$ 432,965	$ 2,386,435	$ 2,344,142	$ 2,116,855
Gross profit	198,097	321,452	155,643	165,669	178,814	337,057	168,340	154,427	840,861	838,638	757,259
Net income (loss) attributable to G-III (in dollars)	$ (20,104)	$ 70,564	$ (1,293)	$ 2,771	$ 7,964	$ 87,156	$ 12,453	$ 6,760	$ 51,938	$ 114,333	$ 110,361
Net income (loss) per common share
Basic (in dollars per share)	$ (0.42)	$ 1.54	$ (0.03)	$ 0.06	$ 0.17	$ 1.92	$ 0.28	$ 0.15	$ 1.12	$ 2.52	$ 2.55
Diluted (in dollars per share)	$ (0.42)	$ 1.50	$ (0.03)	$ 0.06	$ 0.17	$ 1.87	$ 0.27	$ 0.15	$ 1.10	$ 2.46	$ 2.48