Accumulated Other Comprehensive Income (Loss) (Changes in AOCI by Component) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 28, 2020	Mar. 30, 2019	Mar. 28, 2020	Mar. 30, 2019
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning of period			$ 1,322,481
Other comprehensive income (loss), net of tax	$ (18,465)	$ 7,004	8,833	$ 4,400
End of period	1,245,678	1,314,442	1,245,678	1,314,442
Accumulated foreign currency translation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning of period			(129,399)
Other comprehensive income (loss) before reclassifications			(1,392)
Amounts reclassified from AOCIL			(493)
Other comprehensive income (loss), net of tax			(1,885)
End of period	(131,284)		(131,284)
Accumulated retirement liability
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning of period			(285,734)
Other comprehensive income (loss) before reclassifications			(717)
Amounts reclassified from AOCIL			11,196
Other comprehensive income (loss), net of tax			10,479
End of period	(275,255)		(275,255)
Accumulated gain (loss) on derivatives
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning of period			(344)
Other comprehensive income (loss) before reclassifications			444
Amounts reclassified from AOCIL			(205)
Other comprehensive income (loss), net of tax			239
End of period	(105)		(105)
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning of period	(388,179)	(375,396)	(415,477)	(372,792)
Other comprehensive income (loss) before reclassifications			(1,665)
Amounts reclassified from AOCIL			10,498
Other comprehensive income (loss), net of tax	(18,465)	7,004	8,833	4,400
End of period	$ (406,644)	$ (368,392)	$ (406,644)	$ (368,392)