Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Oct. 28, 2017	Oct. 29, 2016
Statement of Cash Flows [Abstract]
Proceeds from Issuance Initial Public Offering	$ 135	$ 93
Operating activities:
Net income	35,074	22,052
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	24,193	19,449
Share-based compensation expense	11,977	9,014
Deferred income tax expense (benefit)	527	(538)
Other non-cash expenses	67	53
Changes in operating assets and liabilities:
Prepaid income taxes	(3,339)	(4,448)
Inventories	(117,237)	(79,805)
Prepaid expenses and other assets	(12,865)	(18,656)
Accounts payable	69,933	47,240
Income taxes payable	(23,884)	(11,816)
Accrued salaries and wages	3,976	1,016
Deferred rent	12,799	7,623
Other accrued expenses	15,806	5,946
Net cash provided by operating activities	17,027	(2,870)
Investing activities:
Purchases of investment securities	(124,406)	(35,856)
Sales, maturities, and redemptions of investment securities	132,855	72,279
Capital expenditures	(49,518)	(35,714)
Net cash used in investing activities	(41,069)	709
Financing activities:
Proceeds from exercise of options to purchase common stock	3,797	2,736
Common shares withheld for taxes	(1,063)	(1,819)
Excess tax benefit related to exercises of stock options, vesting of restricted stock units, and vesting of performance-based restricted units	0	1,607
Proceeds from (Payments for) Other Financing Activities	2	0
Net cash provided by financing activities	2,871	2,617
Net (decrease) increase in cash and cash equivalents	(21,171)	456
Cash and cash equivalents at beginning of period	76,088	53,081
Cash and cash equivalents at end of period	54,917	53,537
Supplemental disclosures of cash flow information:
Increase in accrued purchases of property and equipment	$ (11,266)	$ (80)