Total income tax expense (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 28, 2012	Dec. 30, 2011	Dec. 31, 2010
Current
Federal	$ 23,562	$ 20,544	$ 17,383
Foreign	852	656	758
State	4,304	4,587	4,275
Current Income Tax Expense	28,718	25,787	22,416
Deferred
Federal	(3,378)	(3,013)	(2,474)
State	(816)	(650)	(755)
Deferred Income Tax Expense	(4,194)	(3,663)	(3,229)
Total	$ 24,524	$ 22,124	$ 19,187