Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 28, 2020	Jun. 30, 2019	Jun. 28, 2020	Jun. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ (1,142)	$ 48,749	$ 19,335	$ 81,853
Available-for-sale investments:
Net unrealized gain (loss), net of tax of ($836) and $239 in the three-month periods and net of tax of ($1,788) and $507 in the six-month periods, respectively	12,451	2,311	8,590	4,562
Reclassification of credit loss on investments	(85)	0	75	0
Reclassification of net realized (gain) loss into current operations	(955)	(382)	(2,805)	(422)
Net change related to available-for-sale investments	11,411	1,929	5,860	4,140
Foreign currency translation adjustments:
Foreign currency translation adjustments	1,903	(663)	(5,462)	(445)
Other comprehensive income, net of tax	13,314	1,266	398	3,695
Total comprehensive income	$ 12,172	$ 50,015	$ 19,733	$ 85,548