Amounts Reclassified Out of Accumulated Other Comprehensive Income - Reclassification out of accumulated other comprehensive (loss) income (Details) - USD ($) $ in Thousands		12 Months Ended
		Sep. 24, 2022	Sep. 25, 2021	Sep. 26, 2020
Accumulated Other Comprehensive Income Loss [Line Items]
Balance beginning		$ (17,584)	$ (25,776)	$ (26,186)
Other comprehensive income before reclassifications		2,904	5,166	(2,805)
Recognition in earnings of net actuarial loss for pension settlement		840	958	1,051
Reclassifications to earnings		1,244	2,068	2,164
Other comprehensive income		4,988	8,192	410
Balance ending		(12,596)	(17,584)	(25,776)
Pension Benefits [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance beginning		(23,303)	(32,286)	(33,733)
Funded status benefit plan obligation		2,199	4,736	(3,052)
Recognition in earnings of net actuarial loss for pension settlement	[1]	840	958	1,051
Reclassifications to earnings	[1]	2,467	3,289	3,448
Other comprehensive income		5,506	8,983	1,447
Balance ending		(17,797)	(23,303)	(32,286)
Post-Retirement Benefits [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance beginning		5,719	6,510	7,547
Funded status benefit plan obligation		(705)	430	247
Other comprehensive income		(518)	(791)	(1,037)
Balance ending		5,201	5,719	6,510
Amortization of Prior Service Credits [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Reclassifications to earnings	[1]	498	(498)	(498)
Amortization of Net (Gain) [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Reclassifications to earnings	[1]	$ 725	$ (723)	$ (786)

[1] These amounts are included in the computation of net periodic benefit cost. See Note 12, “Employee Benefit Plans”.