Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jul. 01, 2017	Jun. 30, 2018	Jul. 01, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 75,149	$ 69,127	$ 148,034	$ 137,386
Other comprehensive income (loss), net of tax effects:
Foreign currency translation adjustments	(19,110)	7,866	(7,052)	10,255
Changes in unrealized holding gains or losses on available-for-sale securities, net of reclassification adjustment for realized gains and losses	0	(218)	0	248
Changes in defined benefit plan liabilities	(2)	40	148	69
Total other comprehensive income (loss), net of tax effects	(19,112)	7,688	(6,904)	10,572
Comprehensive income	$ 56,037	$ 76,815	$ 141,130	$ 147,958