Components of and Changes in Accumulated Other Comprehensive Income, Net of Related Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 30, 2017	Dec. 31, 2016	Dec. 26, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ 542,557
Other comprehensive income (loss)	(73)	$ 399	$ (2,303)
Ending Balance	650,672	542,557
Unrealized Holding Gains (Losses) on Available-for-Sale Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(71)	(94)	105
Other comprehensive income (loss)	(73)	23	(199)
Ending Balance	(144)	(71)	(94)
Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(3,018)	(3,394)	(1,290)
Other comprehensive income (loss)		376	(2,104)
Ending Balance	(3,018)	(3,018)	(3,394)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(3,089)	(3,488)	(1,185)
Ending Balance	$ (3,162)	$ (3,089)	$ (3,488)