Quarterly Results of Operations (Unaudited) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 29, 2012	Sep. 29, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 24, 2011	Jun. 25, 2011	Mar. 26, 2011	Dec. 29, 2012	Dec. 31, 2011	Dec. 25, 2010
Summary of quarterly results of operations
Net sales	$ 135,014	$ 156,411	$ 144,172	$ 134,823	$ 135,642	$ 130,576	$ 126,957	$ 120,257	$ 570,420	$ 513,432	$ 438,205
Income from operations	22,966	31,131	25,727	24,407	23,722	23,402	20,572	19,941	104,231	87,637	76,807
Net income from continuing operations	15,249	19,756	16,106	15,294	15,157	15,016	12,881	13,148	66,405	56,202	48,101
Net (loss) income from discontinued operations	51	586	3,636	284	1,487	(3,516)	(134)	(762)	4,557	(2,925)	(1,963)
Net income	$ 15,300	$ 20,342	$ 19,742	$ 15,578	$ 16,644	$ 11,500	$ 12,747	$ 12,386	$ 70,962	$ 53,277	$ 46,138
Diluted earnings per share	$ 0.42	$ 0.56	$ 0.54	$ 0.43	$ 0.46	$ 0.32	$ 0.35	$ 0.34	$ 1.94	$ 1.47	$ 1.27