Computation of Earnings Per Common Share - Basic and Diluted Earnings Calculation (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 25, 2020	Jul. 27, 2019	Jul. 25, 2020	Jul. 27, 2019
Basic earnings per unit
Net income	$ 37,024	$ 29,896	$ 4,606	$ 44,175
Weighted-average number of common shares (in shares)	31,750,547	31,487,011	31,677,012	31,469,401
Basic earnings per common share (in dollars per share)	$ 1.17	$ 0.95	$ 0.15	$ 1.40
Diluted earnings per unit
Weighted-average number of common shares (in shares)	31,750,547	31,487,011	31,677,012	31,469,401
Potential common stock arising from stock options, and unvested restricted share units (in shares)	377,551	333,285	270,334	333,967
Total shares-diluted (in shares)	32,128,098	31,820,296	31,947,346	31,803,368
Diluted earnings per common share (in dollars per share)	$ 1.15	$ 0.94	$ 0.14	$ 1.39
Anti-dilutive weighted shares excluded from the calculation of earnings per share (in shares)	3,539,999	10,287,752	6,117,998	10,307,698
Potential shares of common stock issuable on exercise of convertible senior notes	0	0	0	0
Stock-based awards
Diluted earnings per unit
Anti-dilutive weighted shares excluded from the calculation of earnings per share (in shares)	367,191	276,284	371,068	296,230
Convertible senior notes
Diluted earnings per unit
Anti-dilutive weighted shares excluded from the calculation of earnings per share (in shares)	1,586,404	5,005,734	2,873,465	5,005,734
Note Warrant
Diluted earnings per unit
Anti-dilutive weighted shares excluded from the calculation of earnings per share (in shares)	1,586,404	5,005,734	2,873,465	5,005,734