Amounts Reclassified Out of Accumulated Other Comprehensive Income - Reclassification out of accumulated other comprehensive income (loss) (Details) - USD ($) $ in Thousands		3 Months Ended
		Dec. 25, 2021	Dec. 26, 2020
Accumulated Other Comprehensive Income Loss [Line Items]
Balance beginning		$ (17,584)	$ (25,776)
Reclassifications to earnings		294	593
Other comprehensive income		294	593
Balance ending		(17,290)	(25,183)
Pension Benefits [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance beginning		(23,303)	(32,286)
Reclassifications to earnings	[1]	599	898
Other comprehensive income		599	898
Balance ending		(22,704)	(31,388)
Post-Retirement Benefits [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance beginning		5,719	6,510
Amortization of net gain and prior service credits	[1]	(305)	(305)
Other comprehensive income		(305)	(305)
Balance ending		$ 5,414	$ 6,205

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