Reconciliation of the beginning and ending amount of unrecognized tax benefits (Detail) (USD $)	12 Months Ended
	Dec. 28, 2012	Dec. 30, 2011
Schedule Of Unrecognized Tax Benefits [Line Items]
Balance	$ 388,000	$ 376,000
Additions based on tax positions related to the current year	275,000	83,000
Additions for tax positions of prior years	317,000	0
Reductions due to lapse of statute of limitations	(72,000)	(55,000)
Reductions due to change in accounting method	0	(16,000)
Settlements	0	0
Balance	$ 908,000	$ 388,000