Computation of Earnings Per Common Share - Basic and Diluted Earnings Calculation (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Apr. 27, 2019	Apr. 28, 2018
Basic earnings per unit
Net income	$ 14,279	$ 17,231
Weighted-average number of common shares (in shares)	31,451,809	31,190,366
Basic earnings per common share (in dollars per share)	$ 0.45	$ 0.55
Diluted earnings per unit
Weighted-average number of common shares (in shares)	31,451,809	31,190,366
Potential common stock arising from stock options, and unvested restricted share units (in shares)	334,650	602,549
Potential shares of common stock issuable on exercise of convertible senior notes	0	614,999
Total shares-diluted (in shares)	31,786,459	32,407,914
Diluted earnings per common share (in dollars per share)	$ 0.45	$ 0.53
Anti-dilutive weighted shares excluded from the calculation of earnings per share (in shares)	10,277,839	9,477,316
Stock-based awards
Diluted earnings per unit
Anti-dilutive weighted shares excluded from the calculation of earnings per share (in shares)	266,371	80,847
Convertible senior notes
Diluted earnings per unit
Anti-dilutive weighted shares excluded from the calculation of earnings per share (in shares)	5,005,734	4,390,735
Warrants
Diluted earnings per unit
Anti-dilutive weighted shares excluded from the calculation of earnings per share (in shares)	5,005,734	5,005,734