Amounts Reclassified Out of Accumulated Other Comprehensive Income - Reclassification out of accumulated other comprehensive (loss) income (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Mar. 30, 2019	Mar. 31, 2018	Mar. 30, 2019	Mar. 31, 2018
Accumulated Other Comprehensive Income Loss [Line Items]
Balance beginning		$ (24,118)	$ (28,055)	$ (24,670)	$ (28,812)
Amortization of net loss		552	757	1,104	1,514
Other comprehensive income		552	757	1,104	1,514
Balance ending		(23,566)	(27,298)	(23,566)	(27,298)
Pension Benefits [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance beginning		(32,314)	(36,390)	(33,180)	(37,311)
Amortization of net loss	[1]	867	921	1,733	1,842
Other comprehensive income		867	921	1,733	1,842
Balance ending		(31,447)	(35,469)	(31,447)	(35,469)
Post-Retirement Benefits [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance beginning		8,196	8,335	8,510	8,499
Amortization of net gain and prior service credits	[1]	(315)	(164)	(629)	(328)
Other comprehensive income		(315)	(164)	(629)	(328)
Balance ending		$ 7,881	$ 8,171	$ 7,881	$ 8,171

[1] These amounts are included in the computation of net periodic benefit cost. See Note 14, “Pension Plans and Other Postretirement Benefits.”