Reconciliation of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 26, 2020	Dec. 28, 2019
Income Tax Disclosure [Abstract]
Balance at beginning of year	$ 811	$ 836
Increases related to current year tax positions		101
Increases (decreases) related to prior year tax positions	13	(63)
Decreases related to lapse of statute of limitations	(12)	(63)
Balance at end of year	$ 812	$ 811