Share Based Compensation - Outstanding stock options (Details) (USD $) In Thousands, except Share data, unless otherwise specified	0 Months Ended	12 Months Ended
	Mar. 25, 2013	Jan. 31, 2014
Number of options
Outstanding, beginning of period (in shares)		910,629
Granted (in shares)	198,900	198,900
Exercised (in shares)		(158,971)
Forfeited (in shares)		(4,425)
Expired (in shares)		0
Outstanding, end of period (in shares)		946,133
Weighted average exercise price
Outstanding, beginning of period (in usd per share)		$ 23.36
Granted (in usd per share)		$ 32.85
Exercised (in usd per share)		$ 14.28
Forfeited (in usd per share)		$ 23.34
Expired (in usd per share)		$ 0.00
Outstanding, end of period (in usd per share)		$ 26.88
Aggregate intrinsic value, Outstanding, end of period		$ 10,003
Weighted average remaining contractual term (years), Outstanding, end of period		2 years 7 months 17 days
Number of options, Outstanding exercisable, end of period		439,783
Weighted average exercise price, Outstanding exercisable, end of period		$ 23.06
Aggregate intrinsic value, Outstanding exercisable, end of period		$ 6,327
Weighted average remaining contractual term (years), Outstanding exercisable, end of period		1 year 11 months 4 days