Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 01, 2018	Jul. 02, 2017	Jul. 01, 2018	Jul. 02, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 56,196	$ 56,495	$ 93,413	$ 101,966
Cash flow hedges:
Net unrealized gain (loss), net of tax of $0 and $7 in the three-month periods and net of tax of $0 and $3 in the six-month periods, respectively	0	59	0	(12)
Reclassification of net realized (gain) loss into current operations	0	(9)	0	35
Net change related to cash flow hedges	0	50	0	23
Available-for-sale investments:
Net unrealized gain (loss), net of tax of $8 and $58 in the three-month periods and net of tax of $(106) and $150 in the six-month periods, respectively	490	307	(702)	818
Reclassification of net realized (gain) loss into current operations	(247)	(42)	(269)	(107)
Net change related to available-for-sale investments	243	265	(971)	711
Foreign currency translation adjustments:
Foreign currency translation adjustments	(7,253)	10,263	(3,197)	12,744
Other comprehensive income (loss), net of tax	(7,010)	10,578	(4,168)	13,478
Total comprehensive income	$ 49,186	$ 67,073	$ 89,245	$ 115,444