Revenue Recognition (Details) - USD ($) $ in Thousands	Jul. 31, 2018	Jan. 31, 2018		Jul. 31, 2017
Assets
Accounts receivable, net	$ 447,576	$ 294,430	[1]	$ 287,570	[1]
Inventories	678,571	553,323		655,272
Prepaid expenses and other current assets	100,688	51,014		58,653
Deferred income tax assets, net	28,360	11,439		16,081
Liabilities
Accrued expenses	95,464	95,055		82,387
Customer refund liabilities	204,360
Equity
Retained earnings	640,774	$ 674,542		$ 593,501
Without Adoption of ASC 606
Assets
Accounts receivable, net	304,369
Inventories	714,793
Prepaid expenses and other current assets	68,422
Deferred income tax assets, net	11,816
Liabilities
Accrued expenses	94,018
Customer refund liabilities	0
Equity
Retained earnings	690,786
Impact of Adoption of ASC 606
Assets
Accounts receivable, net	143,207
Inventories, adjustments	(36,222)
Prepaid expenses and other current assets	32,266
Deferred income tax assets, net	16,544
Liabilities
Accrued expenses	1,446
Customer refund liabilities	204,360
Equity
Retained earnings, adjustments	$ (50,012)

[1] Also, net of accrued returns and sales discounts