CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY (Unaudited) - USD ($) $ in Thousands	Total	Cumulative Effect, Period Of Adoption, Adjustment	Common Stock [Member]	Additional Paid-in Capital [Member]	AOCI Attributable to Parent [Member]	Retained Earnings [Member]	Retained Earnings [Member] Cumulative Effect, Period Of Adoption, Adjustment
Beginning balance at Jan. 26, 2019	$ 804,168		$ 10,477	$ 22,489	$ (1,282)	$ 772,484
Beginning balance (shares) at Jan. 26, 2019			31,430,031
Increase (Decrease) in Stockholders' Equity
Stock options exercised	182		$ 5	177
Stock options exercised (shares)			16,870
Stock-based compensation	5,756		$ 2	5,754
Stock-based compensation (shares)			3,237
Issuance of restricted stock, net of tax withholdings	(845)		$ 12	(857)
Issuance of restricted stock, net of tax withholdings (shares)			39,785
Other comprehensive loss	(3)				(3)
Net income	44,175					44,175
Ending balance at Jul. 27, 2019	853,433		$ 10,496	27,563	(1,285)	816,659
Ending balance (shares) at Jul. 27, 2019			31,489,923
Beginning balance at Apr. 27, 2019	821,177		$ 10,493	25,217	(1,296)	786,763
Beginning balance (shares) at Apr. 27, 2019			31,478,851
Increase (Decrease) in Stockholders' Equity
Stock options exercised	76		$ 2	74
Stock options exercised (shares)			7,020
Stock-based compensation	2,277		$ 1	2,276
Stock-based compensation (shares)			1,709
Issuance of restricted stock, net of tax withholdings	(4)		$ 0	(4)
Issuance of restricted stock, net of tax withholdings (shares)			2,343
Other comprehensive loss	11				11
Net income	29,896					29,896
Ending balance at Jul. 27, 2019	853,433		$ 10,496	27,563	(1,285)	816,659
Ending balance (shares) at Jul. 27, 2019			31,489,923
Beginning balance at Jan. 25, 2020	$ 868,604		$ 10,528	30,158	(1,781)	829,699
Beginning balance (shares) at Jan. 25, 2020	31,583,938		31,583,938
Increase (Decrease) in Stockholders' Equity
Stock options exercised	$ 3,608		$ 71	3,537
Stock options exercised (shares)			212,527
Stock-based compensation	6,694		$ 1	6,693
Stock-based compensation (shares)			3,348
Issuance of restricted stock, net of tax withholdings	(329)		$ 12	(341)
Issuance of restricted stock, net of tax withholdings (shares)			37,117
Equity component of the settlement of 0.75% convertible senior notes due 2021, net of taxes	(8,975)			(8,975)
Purchase of warrants	(7,176)			(7,176)
Settlement of convertible note hedges related to extinguishment of convertible debt	7,197			7,197
Other comprehensive loss	(10)				(10)
Net income	4,606					4,606
Ending balance at Jul. 25, 2020	$ 873,748		$ 10,612	31,093	(1,791)	833,834
Ending balance (shares) at Jul. 25, 2020	31,836,930		31,836,930
Beginning balance at Apr. 25, 2020	$ 833,894		$ 10,544	28,352	(1,812)	796,810
Beginning balance (shares) at Apr. 25, 2020			31,632,661
Increase (Decrease) in Stockholders' Equity
Stock options exercised	3,365		$ 65	3,300
Stock options exercised (shares)			197,102
Stock-based compensation	4,373		$ 1	4,372
Stock-based compensation (shares)			1,920
Issuance of restricted stock, net of tax withholdings	(3)		$ 2	(5)
Issuance of restricted stock, net of tax withholdings (shares)			5,247
Equity component of the settlement of 0.75% convertible senior notes due 2021, net of taxes	(5,004)			(5,004)
Purchase of warrants	(6,777)			(6,777)
Settlement of convertible note hedges related to extinguishment of convertible debt	6,855			6,855
Other comprehensive loss	21				21
Net income	37,024					37,024
Ending balance at Jul. 25, 2020	$ 873,748		$ 10,612	$ 31,093	$ (1,791)	$ 833,834
Ending balance (shares) at Jul. 25, 2020	31,836,930		31,836,930
Increase (Decrease) in Stockholders' Equity
Cumulative effect from implementation of ASU 2016-13		$ (471)					$ (471)