Net Income per Common Share - Reconciliation between basic and diluted net income per share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Apr. 30, 2022	Apr. 30, 2021
Net Income (Loss) per Common Share
Net income attributable to G-III Apparel Group, Ltd.	$ 30,634	$ 26,321
Basic net income (loss) per share:
Basic common shares	48,016	48,377
Basic net income (loss) per share (in dollars per share)	$ 0.64	$ 0.54
Diluted net income (loss) per share:
Basic common shares	48,016	48,377
Diluted restricted stock awards and stock options	1,092	1,133
Diluted common shares	49,108	49,510
Diluted net income (loss) per share (in dollars per share)	$ 0.62	$ 0.53