Accumulated Other Comprehensive Income - Changes in AOCI (Details) $ in Thousands	9 Months Ended
	Oct. 01, 2016 USD ($)
Changes in Accumulated Other Comprehensive Income, by Component
Beginning Balance	$ 222,187
Ending Balance	239,420
Unrealized Gains and Losses on Available-for-Sale Securities [Member]
Changes in Accumulated Other Comprehensive Income, by Component
Beginning Balance	(1,262)
Other comprehensive income (loss) before reclassifications	666
Amounts reclassified from accumulated other comprehensive income	186
Net current period other comprehensive income (loss)	852
Ending Balance	(410)
Foreign Currency Items [Member]
Changes in Accumulated Other Comprehensive Income, by Component
Beginning Balance	(8,781)
Other comprehensive income (loss) before reclassifications	(1,871)
Amounts reclassified from accumulated other comprehensive income	0
Net current period other comprehensive income (loss)	(1,871)
Ending Balance	(10,652)
Accumulated other comprehensive income (loss) [Member]
Changes in Accumulated Other Comprehensive Income, by Component
Beginning Balance	(10,043)
Other comprehensive income (loss) before reclassifications	(1,205)
Amounts reclassified from accumulated other comprehensive income	186
Net current period other comprehensive income (loss)	(1,019)
Ending Balance	$ (11,062)