Pension Plans and Other Postretirement Benefits - Components of Net Periodic Benefit Costs (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 29, 2018	Dec. 30, 2017
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 986	$ 944
Expected return on plan assets	(431)	(474)
Amortization of net loss (gain)	866	921
Net periodic benefit cost	1,421	1,391
Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	69	69
Amortization of prior service credits	(124)	(124)
Amortization of net loss (gain)	(190)	(164)
Net periodic benefit cost	$ (245)	$ (219)