QUARTERLY FINANCIAL DATA (UNAUDITED) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Jan. 31, 2020	Oct. 31, 2019	Jul. 31, 2019	Apr. 30, 2019	Jan. 31, 2019	Oct. 31, 2018	Jul. 31, 2018	Apr. 30, 2018	Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Net sales	$ 754,617	$ 1,128,403	$ 643,892	$ 633,552	$ 766,785	$ 1,072,982	$ 624,698	$ 611,743	$ 3,160,464	$ 3,076,208	$ 2,806,938
Gross profit	251,088	399,019	231,769	236,064	258,938	382,100	231,544	234,527	1,117,940	1,107,109	1,054,739
Net income	$ 25,288	$ 95,387	$ 11,119	$ 12,043	$ 24,080	$ 94,025	$ 10,077	$ 9,885	$ 143,837	$ 138,067	$ 62,124
NET INCOME PER COMMON SHARE:
Basic (in dollars per share)	$ 0.53	$ 2.00	$ 0.23	$ 0.25	$ 0.49	$ 1.91	$ 0.20	$ 0.20	$ 2.98	$ 2.81	$ 1.27
Diluted (in dollars per share)	$ 0.52	$ 1.97	$ 0.23	$ 0.24	$ 0.48	$ 1.86	$ 0.20	$ 0.20	$ 2.94	$ 2.75	$ 1.25