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. 26, 2016	Mar. 28, 2015	Mar. 26, 2016	Mar. 28, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance beginning		$ (47,414)	$ (44,816)	$ (48,883)	$ (45,905)
Other comprehensive income before reclassifications		(117)	(500)	60	(727)
Reclassifications to earnings		1,560	1,303	2,852	2,619
Other comprehensive income		1,443	803	2,912	1,892
Balance ending		(45,971)	(44,013)	(45,971)	(44,013)
Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance beginning		(801)	(1,410)	(1,311)	(1,540)
Other comprehensive income before reclassifications		(117)	(500)	60	(727)
Reclassifications to earnings	[1]	259	344	592	701
Other comprehensive income		142	(156)	652	(26)
Balance ending		(659)	(1,566)	(659)	(1,566)
Pension Benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance beginning		(51,702)	(47,904)	(52,836)	(49,034)
Other comprehensive income		1,475	1,131	2,609	2,261
Balance ending		(50,227)	(46,773)	(50,227)	(46,773)
Amortization of Net Loss [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassifications to earnings	[2]	1,475	1,131	2,609	2,261
Post-Retirement Benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance beginning		5,089	4,498	5,264	4,669
Other comprehensive income		(174)	(172)	(349)	(343)
Balance ending		4,915	4,326	4,915	4,326
Amortization of Prior Service Credits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassifications to earnings	[2]	(100)	(123)	(200)	(245)
Amortization of Net (Gain) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassifications to earnings	[2]	$ (74)	$ (49)	$ (149)	$ (98)

[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 13, “Pension Plans and Other Postretirement Benefits”.