Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 29, 2018	Sep. 30, 2017	Sep. 29, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 53,546	$ 42,808	$ 131,900	$ 130,338
Other comprehensive (loss) income:
Pension and postemployment adjustment, net of tax	(115)	(60)	648	(441)
Unrealized loss on investments	0	(1,710)	0	(1,235)
Foreign currency translation adjustments	(7,832)	1,531	(24,816)	2,912
Comprehensive income	$ 45,599	$ 42,569	$ 107,732	$ 131,574