Amounts Reclassified Out of Accumulated Other Comprehensive Income - Reclassification out of accumulated other comprehensive income (loss) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Jun. 24, 2023	Jun. 25, 2022	Jun. 24, 2023	Jun. 25, 2022
Accumulated Other Comprehensive Income Loss [Line Items]
Balance beginning				$ (12,596)
Recognition in earnings of net actuarial loss for pension settlement			$ 634		$ 634
Other comprehensive income		164	927	491	1,515
Balance ending		(12,105)		(12,105)
Pension Benefits [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance beginning		(16,834)	(22,104)	(17,797)	(23,303)
Reclassifications to earnings	[1]	482	598	1,445	1,797
Recognition in earnings of net actuarial loss for pension settlement		0	634	0	634
Other comprehensive income		482	1,232	1,445	2,431
Balance ending		(16,352)	(20,872)	(16,352)	(20,872)
Post-Retirement Benefits [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance beginning		4,565	5,108	5,201	5,719
Other comprehensive income		(318)	(305)	(954)	(916)
Balance ending		4,247	4,803	4,247	4,803
Accumulated Defined Benefit Plans Adjustment Net Prior Service Cost Credit Member
Accumulated Other Comprehensive Income Loss [Line Items]
Balance beginning		(12,269)	(16,996)	(12,596)	(17,584)
Reclassifications to earnings		164	293	491	881
Recognition in earnings of net actuarial loss for pension settlement		0	634	0	634
Amortization of net gain and prior service credits	[1]	(318)	(305)	(954)	(916)
Other comprehensive income		164	927	491	1,515
Balance ending		$ (12,105)	$ (16,069)	$ (12,105)	$ (16,069)

[1] These amounts are included in the computation of net periodic benefit cost. See Note 15, “Pension Plans and Other Postretirement Benefits.”