Amounts Reclassified Out of Accumulated Other Comprehensive Income - Reclassification out of accumulated other comprehensive (loss) income (Details) - USD ($) $ in Thousands		12 Months Ended
		Sep. 24, 2016	Sep. 26, 2015	Sep. 27, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance beginning		$ (48,883)	$ (45,905)	$ (47,353)
Other comprehensive income before reclassifications		(4,569)	(10,202)	(3,779)
Recognition in earnings of net actuarial loss for pension settlement		2,000	2,000	0
Reclassifications to earnings		5,620	5,224	5,227
Other comprehensive income (loss)		3,051	(2,978)	1,448
Balance ending		(45,832)	(48,883)	(45,905)
Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance beginning		(1,311)	(1,540)	(2,428)
Other comprehensive income before reclassifications		6	(1,159)	(518)
Reclassifications to earnings	[1]	1,100	1,388	1,406
Other comprehensive income (loss)		1,106	229	888
Balance ending		(205)	(1,311)	(1,540)
Pension Benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance beginning		(52,836)	(49,034)	(49,987)
Funded status benefit plan obligation		(5,773)	(10,324)	(3,539)
Recognition in earnings of net actuarial loss for pension settlement	[2]	2,000	2,000	0
Other comprehensive income (loss)		1,445	(3,802)	953
Balance ending		(51,391)	(52,836)	(49,034)
Amortization of Net Loss [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassifications to earnings	[2]	5,218	4,522	4,492
Post-Retirement Benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance beginning		5,264	4,669	5,062
Funded status benefit plan obligation		1,198	1,281	278
Other comprehensive income (loss)		500	595	(393)
Balance ending		5,764	5,264	4,669
Amortization of Prior Service Credits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassifications to earnings	[2]	(399)	(490)	(490)
Amortization of Net (Gain) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassifications to earnings	[2]	$ (299)	$ (196)	$ (181)

[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 10, “Employee Benefit Plans”.