Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated deficit [Member]	Unrestricted stock [Member]
Balance at Jan. 28, 2017	$ 331,405	$ 549	$ 321,603	$ 9,253
Balance, common stock, shares at Jan. 28, 2017		54,904,954
Share-based compensation expense	16,114		16,114
Issuance of unrestricted stock awards	238	$ 0	238
Issuance of unrestricted stock awards (in shares)					4,464
Exercise of options and warrants to purchase common stock	9,601	$ 3	9,598
Exercise of options and warrants to purchase common stock (in shares)		327,980
Vesting of restricted stock units and performance-based restricted stock units	(2)		0
Vesting of restricted stock units (in shares)		(229,553)
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures		$ 2
Common Shares Withheld for Taxes		33,327
Common Shares Withheld	(1,504)	$ 0	(1,504)
Issuance of common stock to employees under employee stock purchase plan	251		251
Issuance of common stock to employees under employee stock purchase plan (in shares)		4,465
Net income	102,451			102,451
Balance at Feb. 03, 2018	458,558	$ 554	346,300	111,704
Balance, common stock, shares at Feb. 03, 2018		55,438,089
Cumulative Effect on Retained Earnings, Net of Tax				486
Issuance of unrestricted stock awards	11,807	$ 0	11,807
Issuance of unrestricted stock awards (in shares)		0
Exercise of options and warrants to purchase common stock	4,027	$ 1	4,026
Exercise of options and warrants to purchase common stock (in shares)		145,157
Vesting of restricted stock units and performance-based restricted stock units	(1,987)		(1,987)
Vesting of restricted stock units (in shares)		(21,810)
Issuance of common stock (in shares)		(305,201)			(2,056)
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures	3	$ 3
Common Shares Withheld for Taxes		113,058
Common Shares Withheld	$ (7,990)	$ (1)	(7,989)
Common shares withheld for taxes (in shares)	(21,810)
Stock Repurchased and Retired During Period, Value	$ 2,000
Stock Issued During Period, Value, New Issues	(180)		(180)
Issuance of common stock to employees under employee stock purchase plan	365		365
Issuance of common stock to employees under employee stock purchase plan (in shares)		3,413
Net income	149,645			149,645
Balance at Feb. 02, 2019	$ 615,094	$ 557	352,702	261,835
Balance, common stock, shares at Feb. 02, 2019	55,759,048	55,759,048
Issuance of unrestricted stock awards	$ 12,136		12,136
Issuance of unrestricted stock awards (in shares)		0
Exercise of options and warrants to purchase common stock	4,109	$ 2	4,107
Exercise of options and warrants to purchase common stock (in shares)		141,582
Issuance of common stock (in shares)		(227,020)			(1,634)
Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures	2	$ 2
Common Shares Withheld for Taxes		83,121
Common Shares Withheld	$ (10,367)	$ (1)	(10,366)
Common shares withheld for taxes (in shares)	(337,552)	(337,552)
Stock Repurchased and Retired During Period, Value	$ 36,885	$ (3)	36,882
Stock Issued During Period, Value, New Issues	(198)	$ 0	(198)
Issuance of common stock to employees under employee stock purchase plan	435		435
Issuance of common stock to employees under employee stock purchase plan (in shares)		3,456
Net income	175,056
Balance at Feb. 01, 2020	$ 759,778	$ 557	$ 322,330	$ 436,891
Balance, common stock, shares at Feb. 01, 2020	55,712,067	55,712,067