Amounts Reclassified Out of Accumulated Other Comprehensive Income - Reclassification out of accumulated other comprehensive income (loss) (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Jun. 29, 2019	Jun. 30, 2018	Jun. 29, 2019	Jun. 30, 2018
Accumulated Other Comprehensive Income Loss [Line Items]
Balance beginning		$ (23,566)	$ (27,298)	$ (24,670)	$ (28,812)
Amortization of net loss		552	757	1,656	2,271
Other comprehensive income		552	757	1,656	2,271
Balance ending		(23,014)	(26,541)	(23,014)	(26,541)
Pension Benefits [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance beginning		(31,447)	(35,469)	(33,180)	(37,311)
Amortization of net loss	[1]	867	920	2,600	2,762
Other comprehensive income		867	920	2,600	2,762
Balance ending		(30,580)	(34,549)	(30,580)	(34,549)
Post-Retirement Benefits [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance beginning		7,881	8,171	8,510	8,499
Amortization of net gain and prior service credits	[1]	(315)	(163)	(944)	(491)
Other comprehensive income		(315)	(163)	(944)	(491)
Balance ending		$ 7,566	$ 8,008	$ 7,566	$ 8,008

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