Consolidated Statements Of Comprehensive Income (Loss) (Parenthetical) - USD ($)	3 Months Ended		6 Months Ended
	Mar. 31, 2018	Apr. 01, 2017	Mar. 31, 2018	Apr. 01, 2017
Statement of Comprehensive Income [Abstract]
Unrealized hedge gain (loss) arising during the period, tax	$ 300,000	$ 100,000	$ 400,000	$ 400,000
Net hedge loss reclassified into earnings, tax	200,000	100,000	300,000	100,000
Foreign currency translation adjustment, tax	0	0	0	0
Unrealized gain (loss) marketable securities tax	0	0	0	0
Amortization of net actuarial pension loss included in net income, tax	$ 200,000	$ 200,000	$ 300,000	$ 400,000