Pension Plans and Other Postretirement Benefits - Components of Net Periodic Benefit Costs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 26, 2022	Mar. 27, 2021	Mar. 26, 2022	Mar. 27, 2021
Defined Benefit Plan Disclosure [Line Items]
Pension settlement charge			$ 0	$ 570
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 560	$ 534	1,119	1,068
Expected return on plan assets	(354)	(319)	(708)	(638)
Amortization of net loss (gain)	600	898	1,199	1,796
Pension settlement charge	0	570	0	570
Net periodic benefit cost	806	1,683	1,610	2,796
Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	20	19	40	38
Amortization of prior service credits	(125)	(125)	(249)	(249)
Amortization of net loss (gain)	(181)	(180)	(362)	(361)
Net periodic benefit cost	$ (286)	$ (286)	$ (571)	$ (572)