Consolidated Statements Of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2018	Apr. 01, 2017	Mar. 31, 2018	Apr. 01, 2017
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 7,922	$ (1,104)	$ 21,799	$ (10,245)
Other comprehensive income (loss), net of tax:
Unrealized hedge gain (loss) arising during the period, net of tax of $0.3 million and $0.1 million in the second quarter of 2018 and 2017, respectively, and $0.4 million and $0.4 million in the first six months of 2018 and 2017, respectively	(2,046)	(515)	(2,959)	2,522
Net hedge (gain) loss reclassified into earnings, net of tax of $0.2 million and $0.1 million in the second quarter of 2018 and 2017, respectively, and $0.3 million and $0.1 million in the first six months of 2018 and 2017, respectively	1,511	(496)	2,084	(852)
Unrealized gain (loss) on hedging instruments	(535)	(1,011)	(875)	1,670
Foreign currency translation adjustment, net of tax of $0 for each period	7,540	4,992	12,769	(13,660)
Unrealized gain (loss) on marketable securities, net of tax of $0 for each period	(267)	68	(446)	(71)
Amortization of net actuarial pension loss included in net income, net of tax of $0.2 million in both the second quarter of 2018 and 2017, and $0.3 million and $0.4 million in the first six months of 2018 and 2017, respectively	386	574	757	1,090
Change in unamortized pension loss during the period related to changes in foreign currency	(465)	(312)	(728)	1,378
Other comprehensive income (loss)	6,659	4,311	11,477	(9,593)
Comprehensive income (loss)	$ 14,581	$ 3,207	$ 33,276	$ (19,838)