Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Oct. 01, 2017	Sep. 30, 2018	Oct. 01, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 80,436	$ 102,493	$ 173,849	$ 204,459
Cash flow hedges:
Net unrealized gain (loss), net of tax of $0 and ($8) in the three-month periods and net of tax of $0 and ($5) in the nine-month periods, respectively	0	(4)	0	(16)
Reclassification of net realized (gain) loss into current operations	0	(56)	0	(21)
Net change related to cash flow hedges	0	(60)	0	(37)
Available-for-sale investments:
Net unrealized gain (loss), net of tax of $24 and $41 in the three-month periods and net of tax of ($82) and $191 in the nine-month periods, respectively	522	419	(180)	1,237
Reclassification of net realized (gain) loss into current operations	(266)	(263)	(535)	(370)
Net change related to available-for-sale investments	256	156	(715)	867
Foreign currency translation adjustments:
Foreign currency translation adjustments	(1,881)	5,753	(5,078)	18,497
Other comprehensive income (loss), net of tax	(1,625)	5,849	(5,793)	19,327
Total comprehensive income	$ 78,811	$ 108,342	$ 168,056	$ 223,786