Amounts Reclassified Out of Accumulated Other Comprehensive Income - Reclassification out of accumulated other comprehensive (loss) income (Details) - USD ($) $ in Thousands		12 Months Ended
		Sep. 28, 2019	Sep. 29, 2018	Sep. 30, 2017
Accumulated Other Comprehensive Income Loss [Line Items]
Balance beginning		$ (24,670)	$ (28,812)	$ (45,832)
Other comprehensive income before reclassifications		(3,723)	1,612	5,893
Recognition in earnings of net actuarial loss for pension settlement		0	0	6,100
Reclassifications to earnings		2,207	2,530	5,027
Other comprehensive (loss) income		(1,516)	4,142	17,020
Balance ending		(26,186)	(24,670)	(28,812)
Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance beginning		0	0	(205)
Other comprehensive income before reclassifications		0	0	(10)
Reclassifications to earnings	[1]	0	0	215
Other comprehensive (loss) income		0	0	205
Balance ending		0	0	0
Pension Benefits [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance beginning		(33,180)	(37,311)	(51,391)
Funded status benefit plan obligation		(4,019)	448	2,779
Recognition in earnings of net actuarial loss for pension settlement	[2]	0	0	6,100
Balance ending		(33,733)	(33,180)	(37,311)
Amortization of Net Loss [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Reclassifications to earnings	[2]	3,466	3,683	5,201
Other comprehensive (loss) income		(553)	4,131	14,080
Post-Retirement Benefits [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Balance beginning		8,510	8,499	5,764
Prior service credits		0	0	3,246
Funded status benefit plan obligation		296	1,164	(122)
Other comprehensive (loss) income		(963)	11	2,735
Balance ending		7,547	8,510	8,499
Amortization of Prior Service Credits [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Reclassifications to earnings	[2]	(498)	(498)	0
Amortization of Net (Gain) [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Reclassifications to earnings	[2]	$ (761)	$ (655)	$ (389)

[1] Reclassification of realized losses on cash flow hedges are recognized in interest expense.

[2] These amounts are included in the computation of net periodic benefit cost.  See Note 11, “Employee Benefit Plans”.