Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Oct. 01, 2016	Sep. 30, 2017	Oct. 01, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 136,104	$ 124,856	$ 373,483	$ 347,125
Foreign currency translation	26,827	2,480	94,209	(12,954)
Unrealized gains (losses) on investments before income taxes	318	(1,393)	1,700	3,777
Income tax (expense) benefit from unrealized gains (losses) on investments	(9)	61	(108)	(108)
Unrealized gains (losses) on investments, net of tax	309	(1,332)	1,592	3,669
Retirement liability adjustment before reclassifications	(499)	(183)	(2,030)	(682)
Retirement liability amounts reclassified to selling and administrative expenses	894	832	2,652	2,452
Retirement liability adjustment before income taxes	395	649	622	1,770
Income tax expense from retirement liability adjustment	(183)	(272)	(570)	(1,163)
Retirement liability adjustment, net of tax	212	377	52	607
Other comprehensive income (loss)	27,348	1,525	95,853	(8,678)
Comprehensive income	$ 163,452	$ 126,381	$ 469,336	$ 338,447