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. 25, 2022	Jun. 26, 2021	Jun. 25, 2022	Jun. 26, 2021
Accumulated Other Comprehensive Income Loss [Line Items]
Balance beginning		$ (16,996)	$ (24,020)	$ (17,584)	$ (25,776)
Recognition in earnings of net actuarial loss for pension settlement		634	142	634	712
Reclassifications to earnings		293	593	881	1,779
Other comprehensive income		927	735	1,515	2,491
Balance ending		(16,069)	(23,285)	(16,069)	(23,285)
Pension Benefits [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance beginning		(22,104)	(29,920)	(23,303)	(32,286)
Recognition in earnings of net actuarial loss for pension settlement	[1]	634	142	634	712
Reclassifications to earnings	[1]	598	899	1,797	2,695
Other comprehensive income		1,232	1,041	2,431	3,407
Balance ending		(20,872)	(28,879)	(20,872)	(28,879)
Post-Retirement Benefits [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance beginning		5,108	5,900	5,719	6,510
Amortization of net gain and prior service credits	[1]	(305)	(306)	(916)	(916)
Other comprehensive income		(305)	(306)	(916)	(916)
Balance ending		$ 4,803	$ 5,594	$ 4,803	$ 5,594

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