Amounts Reclassified Out of Accumulated Other Comprehensive Income - Reclassification out of accumulated other comprehensive income (loss) (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Mar. 25, 2023	Mar. 26, 2022	Mar. 25, 2023	Mar. 26, 2022
Accumulated Other Comprehensive Income Loss [Line Items]
Balance beginning				$ (12,596)
Other comprehensive income		$ 163	$ 294	327	$ 588
Balance ending		(12,269)		(12,269)
Pension Benefits [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance beginning		(17,315)	(22,704)	(17,797)	(23,303)
Reclassifications to earnings	[1]	481	600	963	1,199
Other comprehensive income		481	600	963	1,199
Balance ending		(16,834)	(22,104)	(16,834)	(22,104)
Post-Retirement Benefits [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance beginning		4,883	5,414	5,201	5,719
Other comprehensive income		(318)	(306)	(636)	(611)
Balance ending		4,565	5,108	4,565	5,108
Accumulated Defined Benefit Plans Adjustment Net Prior Service Cost Credit Member
Accumulated Other Comprehensive Income Loss [Line Items]
Balance beginning		(12,432)	(17,290)	(12,596)	(17,584)
Reclassifications to earnings		163	294	327	588
Amortization of net gain and prior service credits	[1]	(318)	306	(636)	611
Other comprehensive income		163	294	327	588
Balance ending		$ (12,269)	$ (16,996)	$ (12,269)	$ (16,996)

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