Amounts Reclassified Out of Accumulated Other Comprehensive Income - Reclassification out of accumulated other comprehensive income (loss) (Details) - USD ($) $ in Thousands		3 Months Ended
		Dec. 28, 2019	Dec. 29, 2018
Accumulated Other Comprehensive Income Loss [Line Items]
Balance beginning		$ (26,186)	$ (24,670)
Reclassifications to earnings		541	552
Other comprehensive income		541	552
Balance ending		(25,645)	(24,118)
Pension Benefits [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance beginning		(33,733)	(33,180)
Reclassifications to earnings	[1]	862	866
Other comprehensive income		862	866
Balance ending		(32,871)	(32,314)
Post-Retirement Benefits [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance beginning		7,547	8,510
Amortization of net gain and prior service credits	[1]	(321)	(314)
Other comprehensive income		(321)	(314)
Balance ending		$ 7,226	$ 8,196

[1] These amounts are included in the computation of net periodic benefit cost.  See Note 15, “Pension Plans and Other Postretirement Benefits.”