Share Based Compensation Outstanding stock options (Details) (USD $) In Thousands, except Share data, unless otherwise specified	0 Months Ended		12 Months Ended
	Aug. 27, 2012	Apr. 02, 2012	Jan. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding, January 31, 2011			990,882
Outstanding, January 31, 2011, Weighted average exercise price			$ 20.87
Granted, Number of options	7,600	151,200	158,800
Granted, Weighted average exercise price			$ 31.57
Exercised, Number of options			(160,449)
Exercised, Weighted average exercise price			$ 16.20
Forfeited, Number of options			(70,354)
Forfeited, Weighted average exercise price			$ 23.98
Share-based Compensation Arrangement by Share-based Payment Award, Options, Expirations in Period			(8,250)
Share-based Compensation Arrangements by Share-based Payment Award, Options, Expirations in Period, Weighted Average Exercise Price			$ 16.11
Outstanding, January 31, 2012			910,629
Outstanding, January 31, 2012, Weighted average exercise price			$ 23.36
Outstanding, January 31, 2012, Aggregate intrinsic value			$ 4,716
Outstanding, January 31, 2012, Weighted average remaining contractual term (years)			2 years 10 months 17 days
Exercisable, January 31, 2012, Number of options			401,780
Exercisable, January 31, 2012, Weighted average exercis price			$ 18.65
Exercisable, January 31, 2012, Aggregate intrinsic value			$ 3,514
Exercisable, January 31, 2012, Weighted average remaining contractual term (years)			2 years 1 month 13 days