Earning Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 24, 2012	Mar. 26, 2011
Numerator:
Net earnings	$ 31,180	$ 35,863
Adjustment for earnings allocated to nonvested restricted common stock	(586)	(588)
Net earnings used in calculating basic earnings per share	30,594	35,275
Adjustment for earnings reallocated from non-vested restricted common stock	24	18
Net earnings used in calculating diluted earnings per share	$ 30,618	$ 35,293
Denominator:
Weighted average shares outstanding	48,434,063	49,292,383
Adjustment for non-vested restricted common stock	(1,400,866)	(1,379,644)
Shares used in calculating basic earnings per share	47,033,197	47,912,739
Effect of dilutive stock options	1,124,300	1,264,737
Shares used in calculating diluted earnings per share	48,157,497	49,177,476
Net earnings per share:
Basic	$ 0.65	$ 0.74
Diluted	$ 0.64	$ 0.72
Earnings Per Share (Textual) [Abstract]
Options to purchase shares of common stock being antidilutive	533,792	268,901