Computation of Earnings Per Common Share - Basic and Diluted Earnings Calculation (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 27, 2018	Oct. 28, 2017	Oct. 27, 2018	Oct. 28, 2017
Basic earnings per unit
Net income	$ 27,830	$ 28,776	$ 74,961	$ 111,280
Weighted-average number of common shares (in shares)	31,246,591	31,061,448	31,214,172	31,167,753
Basic earnings per common share (in dollars per share)	$ 0.89	$ 0.93	$ 2.40	$ 3.57
Diluted earnings per unit
Weighted-average number of common shares (in shares)	31,246,591	31,061,448	31,214,172	31,167,753
Potential common stock arising from stock options, and unvested restricted share units (in shares)	587,951	830,126	605,992	654,353
Potential shares of common stock issuable on exercise of convertible senior notes	0	0	245,065	0
Total shares-diluted (in shares)	31,834,542	31,891,574	32,065,229	31,822,106
Diluted earnings per common share (in dollars per share)	$ 0.87	$ 0.90	$ 2.34	$ 3.50
Anti-dilutive weighted shares excluded from the calculation of earnings per share (in shares)	10,133,190	10,136,542	9,834,798	10,113,736
Stock-based awards
Diluted earnings per unit
Anti-dilutive weighted shares excluded from the calculation of earnings per share (in shares)	121,722	125,074	68,395	102,268
Convertible senior notes
Diluted earnings per unit
Anti-dilutive weighted shares excluded from the calculation of earnings per share (in shares)	5,005,734	5,005,734	4,760,669	5,005,734
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	5,005,734	5,005,734