Segments - Information regarding reportable segments (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2017	Jul. 31, 2016
Segment Reporting Information [Line Items]
Net sales		$ 538,006	$ 442,267	$ 1,067,048	$ 899,670
Cost of goods sold		335,115	286,624	662,301	578,358
Gross profit		202,891	155,643	404,747	321,312
Selling, general and administrative		195,849	153,168	393,260	306,273
Depreciation and amortization		10,736	7,672	20,574	14,865
Operating profit (loss)		(3,694)	(5,197)	(9,087)	174
Operating Segments | Wholesale
Segment Reporting Information [Line Items]
Net sales		467,804	361,344	921,116	743,715
Cost of goods sold		316,417	250,475	614,722	508,471
Gross profit		151,387	110,869	306,394	235,244
Selling, general and administrative		128,484	96,613	258,644	193,551
Depreciation and amortization		7,229	5,370	13,613	10,371
Operating profit (loss)		15,674	8,886	34,137	31,322
Operating Segments | Retail
Segment Reporting Information [Line Items]
Net sales		106,436	99,958	205,620	194,950
Cost of goods sold		54,932	55,184	107,267	108,882
Gross profit		51,504	44,774	98,353	86,068
Selling, general and administrative		67,365	56,555	134,616	112,722
Depreciation and amortization		3,507	2,302	6,961	4,494
Operating profit (loss)		(19,368)	(14,083)	(43,224)	(31,148)
Elimination
Segment Reporting Information [Line Items]
Net sales	[1]	(36,234)	(19,035)	(59,688)	(38,995)
Cost of goods sold	[1]	(36,234)	(19,035)	(59,688)	(38,995)
Gross profit	[1]
Selling, general and administrative	[1]
Depreciation and amortization	[1]
Operating profit (loss)	[1]

[1] Represents intersegment sales to the Company's retail operations.