Capital Stock (Details 1) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 29, 2012	Dec. 31, 2011	Dec. 25, 2010
Shares
Beginning Balance	692,800	990,900	1,462,800
Granted, Shares	20,000		30,000
Exercised, Shares	(438,800)	(298,100)	(489,900)
Cancelled			(12,000)
Ending Balance	274,000	692,800	990,900
Options exercisable, Shares	200,000
Weighted Average Price
Beginning Balance	$ 5.46	$ 4.54	$ 3.36
Granted	$ 22.71		$ 19.37
Exercised	$ 4.27	$ 2.41	$ 1.87
Cancelled			$ 6.24
Ending Balance	$ 8.62	$ 5.46	$ 4.54
Balance, Weighted Average Remaining Terms (years)	5 years
Options exercisable, Weighted Average Remaining Terms (years)	4 years
Aggregate Intrinsic Value	$ 6,994,000
Options exercisable, Aggregate Intrinsic Value	$ 5,516,000
Options Exercisable, Weighted Average Exercise Price	$ 6.57
Maximum [Member]
Option Price per share
Beginning balance, option price per share	$ 19.37	$ 19.37	$ 7.74
Option Price per share, granted	$ 22.71		$ 19.37
Option price per share, Exercised	$ 7.74	$ 7.74	$ 6.90
Option price per share, Cancelled			$ 6.24
Ending balance, option price per share	$ 22.71	$ 19.37	$ 19.37
Weighted Average Price
Options Exercisable, Weighted Average Exercise Price	$ 19.37
Minimum [Member]
Option Price per share
Beginning balance, option price per share	$ 2.00	$ 0.47	$ 0.47
Option price per share, Exercised	$ 2.00	$ 0.47	$ 0.75
Ending balance, option price per share	$ 2.54	$ 2.00	$ 0.47
Weighted Average Price
Options Exercisable, Weighted Average Exercise Price	$ 2.54