Consolidated Statements Of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2018	Jul. 01, 2017	Jun. 30, 2018	Jul. 01, 2017
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 16,997	$ (951)	$ 38,796	$ (11,196)
Other comprehensive income (loss), net of tax:
Unrealized hedge gain (loss) arising during the period, net of tax of $0.6 million and $0.3 million in the third quarter of 2018 and 2017, respectively, and $0.1 million and $0 million in the first nine months of 2018 and 2017, respectively	3,910	(2,298)	950	224
Net hedge (gain) loss reclassified into earnings, net of tax of $0 million in both the third quarter of 2018 and 2017, respectively, and $0.3 million and $0.1 million in the first nine months of 2018 and 2017, respectively	242	75	2,327	(777)
Unrealized gain (loss) on hedging instruments	4,152	(2,223)	3,277	(553)
Foreign currency translation adjustment, net of tax of $0 for each period	(21,628)	17,553	(8,859)	3,893
Unrealized gain (loss) on marketable securities, net of tax of $0 for each period	67	21	(379)	(50)
Amortization of net actuarial pension loss included in net income, net of tax of $0.1 million and $0.2 million in the third quarter of 2018 and 2017, respectively, and $0.5 million and $0.7 million in the first nine months of 2018 and 2017, respectively	386	597	1,143	1,687
Change in unamortized pension loss during the period related to changes in foreign currency	884	(1,721)	156	(343)
Other comprehensive income (loss)	(16,139)	14,227	(4,662)	4,634
Comprehensive income (loss)	$ 858	$ 13,276	$ 34,134	$ (6,562)