Consolidated Statements Of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 29, 2019	Jun. 30, 2018	Jun. 29, 2019	Jun. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (14,758)	$ 16,997	$ (37,286)	$ 38,796
Other comprehensive income (loss), net of tax:
Hedge gain (loss) arising during the period, net of tax of $0.2 million and $0.6 million in the third quarter of 2019 and 2018, respectively, and $0 million and $0.1 million in the first nine months of 2019 and 2018, respectively	(2,644)	3,910	(1,818)	950
Net hedge (gain) loss reclassified into earnings, net of tax of $0 million in the third quarter of 2019 and 2018, respectively, and $0.1 million and $0.3 million in the first nine months of 2019 and 2018, respectively	0	242	(549)	2,327
Realized and unrealized gain (loss) on hedging instruments	(2,644)	4,152	(2,367)	3,277
Foreign currency translation adjustment, net of tax of $0 for each period	4,393	(21,628)	(7,209)	(8,859)
Unrealized gain (loss) on marketable securities, net of tax of $0 for each period	175	67	477	(379)
Amortization of net actuarial pension loss included in net income, net of tax of $0.2 million and $0.1 million in the third quarter of 2019 and 2018, respectively, and $0.5 million in the first nine months of 2019 and 2018, respectively	418	386	1,277	1,143
Change in unamortized pension loss during the period related to changes in foreign currency	(230)	884	395	156
Other comprehensive income (loss)	2,112	(16,139)	(7,427)	(4,662)
Comprehensive income (loss)	$ (12,646)	$ 858	$ (44,713)	$ 34,134