CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2017	Oct. 31, 2016	Oct. 31, 2017	Oct. 31, 2016
Income Statement [Abstract]
Net sales	$ 1,024,993	$ 883,476	$ 2,092,040	$ 1,783,145
Cost of goods sold	634,128	562,024	1,296,428	1,140,381
Gross profit	390,865	321,452	795,612	642,764
Selling, general and administrative expenses	242,740	198,274	636,000	504,547
Depreciation and amortization	6,906	8,033	27,480	22,898
Operating profit	141,219	115,145	132,132	115,319
Equity earnings (loss) in unconsolidated affiliates	612	(1,437)	(540)	(820)
Interest and financing charges, net	(13,884)	(1,701)	(33,472)	(3,999)
Income before income taxes	127,947	112,007	98,120	110,500
Income tax expense	46,322	41,443	35,454	38,458
Net income	$ 81,625	$ 70,564	$ 62,666	$ 72,042
Basic:
Net income per common share (in dollars per share)	$ 1.67	$ 1.54	$ 1.29	$ 1.58
Weighted average number of shares outstanding (in shares)	48,846	45,918	48,729	45,713
Diluted:
Net income per common share (in dollars per share)	$ 1.65	$ 1.50	$ 1.27	$ 1.53
Weighted average number of shares outstanding (in shares)	49,528	46,902	49,410	46,947
Net income	$ 81,625	$ 70,564	$ 62,666	$ 72,042
Other comprehensive income:
Foreign currency translation adjustments	4,182	(59)	12,223	3,163
Other comprehensive income (loss)	4,182	(59)	12,223	3,163
Comprehensive income	$ 85,807	$ 70,505	$ 74,889	$ 75,205