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. 28, 2018	Jul. 29, 2017	Jul. 28, 2018	Jul. 29, 2017
Basic earnings per unit
Net income	$ 29,900	$ 43,708	$ 47,131	$ 82,504
Weighted-average number of common shares (in shares)	31,206,340	31,084,019	31,198,349	31,220,719
Basic earnings per common share (in dollars per share)	$ 0.96	$ 1.41	$ 1.51	$ 2.64
Diluted earnings per unit
Weighted-average number of common shares (in shares)	31,206,340	31,084,019	31,198,349	31,220,719
Potential common stock arising from stock options, and unvested restricted share units (in shares)	627,477	580,129	615,014	566,466
Potential shares of common stock issuable on exercise of convertible senior notes	120,196	0	367,597	0
Total shares-diluted (in shares)	31,954,013	31,664,148	32,180,960	31,787,185
Diluted earnings per common share (in dollars per share)	$ 0.94	$ 1.38	$ 1.46	$ 2.60
Anti-dilutive weighted shares excluded from the calculation of earnings per share (in shares)	9,941,638	10,097,177	9,698,425	10,102,333
Stock-based awards
Diluted earnings per unit
Anti-dilutive weighted shares excluded from the calculation of earnings per share (in shares)	50,366	85,709	54,554	90,865
Convertible senior notes
Diluted earnings per unit
Anti-dilutive weighted shares excluded from the calculation of earnings per share (in shares)	4,885,538	5,005,734	4,638,137	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