Consolidated Statements Of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 27, 2020	Jun. 29, 2019	Jun. 27, 2020	Jun. 29, 2019
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ 34,678	$ (14,758)	$ 77,289	$ (37,286)
Other comprehensive income (loss), net of tax:
Hedge loss arising during the period, net of tax benefit of $0.4 million and $0.2 million in the third quarter of 2020 and 2019, respectively, and $1.2 million and $0 million in the first nine months of 2020 and 2019, respectively	(1,148)	(2,644)	(3,790)	(1,818)
Net hedge gain reclassified into earnings, net of tax provision of $0 million in the third quarter of 2020 and 2019, respectively, and $0 million and $0.1 million in the first nine months of 2020 and 2019, respectively	0	0	0	(549)
Realized and unrealized loss on hedging instruments	(1,148)	(2,644)	(3,790)	(2,367)
Foreign currency translation adjustment, net of tax of $0 for each period	3,089	4,393	2,677	(7,209)
Unrealized gain on marketable securities, net of tax of $0 for each period	822	175	278	477
Amortization of net actuarial pension gain included in net income, net of tax provision of $0.3 million and $0.2 million in the third quarter of 2020 and 2019, respectively, and $0.8 million and $0.5 million in the first nine months of 2020 and 2019, respectively	673	418	2,027	1,277
Change in unamortized pension gain (loss) during the period related to changes in foreign currency	(152)	(230)	(693)	395
Other comprehensive income (loss)	3,284	2,112	499	(7,427)
Comprehensive income (loss)	$ 37,962	$ (12,646)	$ 77,788	$ (44,713)