Components of and Changes in Accumulated Other Comprehensive Income, Net of Related Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 26, 2020	Dec. 28, 2019	Dec. 29, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 721,469
Other comprehensive income (loss)	213	$ 3,663	$ (2,713)
Ending Balance	691,835	721,469
Unrealized Holding (Losses) Gains on Available-for-Sale Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	1,120	(930)	(144)
Other comprehensive income (loss)	1,688	2,050	(786)
Ending Balance	2,808	1,120	(930)
Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(3,332)	(4,945)	(3,018)
Other comprehensive income (loss)	(1,475)	1,613	(1,927)
Ending Balance	(4,807)	(3,332)	(4,945)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(2,212)	(5,875)	(3,162)
Other comprehensive income (loss)	213	3,663	(2,713)
Ending Balance	$ (1,999)	$ (2,212)	$ (5,875)