SIGNIFICANT ACCOUNTING POLICIES - Reconciliation between Basic and Diluted Net Income per Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Jan. 31, 2015	Oct. 31, 2014	Jul. 31, 2014	Apr. 30, 2014	Jan. 31, 2014	Oct. 31, 2013	Jul. 31, 2013	Apr. 30, 2013	Jan. 31, 2015	Jan. 31, 2014	Jan. 31, 2013
Accounting Policies [Abstract]
Net income attributable to G-III	$ 22,220	$ 80,615	$ 6,236	$ 1,290	$ 13,055	$ 59,595	$ 3,592	$ 1,118	$ 110,361	$ 77,360	$ 56,875
Basic net income per share:
Basic common shares									21,649	20,323	20,006
Basic net income per share	$ 0.99	$ 3.60	$ 0.29	$ 0.06	$ 0.64	$ 2.92	$ 0.18	$ 0.06	$ 5.10	$ 3.81	$ 2.84
Diluted net income per share:
Basic common shares									21,649	20,323	20,006
Stock options and restricted stock awards									563	541	274
Diluted common shares									22,212	20,864	20,280
Diluted net income per share	$ 0.96	$ 3.53	$ 0.29	$ 0.06	$ 0.62	$ 2.85	$ 0.17	$ 0.05	$ 4.97	$ 3.71	$ 2.80