Accumulated Other Comprehensive Income (Loss) (Changes in AOCI by Component) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 27, 2020	Jun. 29, 2019	Jun. 27, 2020	Jun. 29, 2019
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning of period			$ 1,322,481
Other comprehensive income (loss), net of tax	$ 8,511	$ 5,127	17,344	$ 9,527
End of period	1,245,761	1,355,657	1,245,761	1,355,657
Accumulated foreign currency translation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning of period			(129,399)
Other comprehensive income (loss) before reclassifications			640
Amounts reclassified from AOCIL			(493)
Other comprehensive income (loss), net of tax			147
End of period	(129,252)		(129,252)
Accumulated retirement liability
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning of period			(285,734)
Other comprehensive income (loss) before reclassifications			(889)
Amounts reclassified from AOCIL			17,290
Other comprehensive income (loss), net of tax			16,401
End of period	(269,333)		(269,333)
Accumulated gain (loss) on derivatives
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning of period			(344)
Other comprehensive income (loss) before reclassifications			990
Amounts reclassified from AOCIL			(194)
Other comprehensive income (loss), net of tax			796
End of period	452		452
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning of period	(406,644)	(368,392)	(415,477)	(372,792)
Other comprehensive income (loss) before reclassifications			741
Amounts reclassified from AOCIL			16,603
Other comprehensive income (loss), net of tax	8,511	5,127	17,344	9,527
End of period	$ (398,133)	$ (363,265)	$ (398,133)	$ (363,265)