Components of and Changes in Accumulated Other Comprehensive Income, Net of Related Income Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 01, 2017	Jun. 25, 2016	Jul. 01, 2017	Jun. 25, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			$ 542,557
Other comprehensive income	$ 549	$ 469	750	$ 1,234
Ending Balance	609,490		609,490
Unrealized Holding (Losses) Gains on Available-for-Sale Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			(71)
Other comprehensive income			165
Ending Balance	94		94
Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			(3,018)
Other comprehensive income			585
Ending Balance	(2,433)		(2,433)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance			(3,089)
Other comprehensive income			750
Ending Balance	$ (2,339)		$ (2,339)