Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Apr. 01, 2018	Apr. 02, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 37,217	$ 45,471
Cash flow hedges:
Net unrealized gain (loss), net of tax of $0 and ($4) in 2018 and 2017, respectively	0	(71)
Reclassification of net realized (gain) loss into current operations	0	44
Net change related to cash flow hedges	0	(27)
Available-for-sale investments:
Net unrealized gain (loss), net of tax of ($114) and $92 in 2018 and 2017, respectively	(1,192)	511
Reclassification of net realized (gain) loss into current operations	(22)	(65)
Net change related to available-for-sale investments	(1,214)	446
Foreign currency translation adjustments:
Foreign currency translation adjustments	4,056	2,481
Other comprehensive income (loss), net of tax	2,842	2,900
Total comprehensive income	$ 40,059	$ 48,371