Amounts Reclassified Out of Accumulated Other Comprehensive Income - Reclassification out of accumulated other comprehensive (loss) income (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Jun. 24, 2017	Jun. 25, 2016	Jun. 24, 2017	Jun. 25, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance beginning		$ (43,221)	$ (45,971)	$ (45,832)	$ (48,883)
Other comprehensive income before reclassifications		0	(107)	(10)	(47)
Reclassifications to earnings		1,203	1,382	3,824	4,234
Other comprehensive income		1,203	1,275	3,814	4,187
Balance ending		(42,018)	(44,696)	(42,018)	(44,696)
Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance beginning		0	(659)	(205)	(1,311)
Other comprehensive income before reclassifications		0	(107)	(10)	(47)
Reclassifications to earnings	[1]	0	252	215	844
Other comprehensive income		0	145	205	797
Balance ending		0	(514)	0	(514)
Pension Benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance beginning		(48,791)	(50,227)	(51,391)	(52,836)
Other comprehensive income		1,301	1,304	3,901	3,913
Balance ending		(47,490)	(48,923)	(47,490)	(48,923)
Amortization of Net Loss [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassifications to earnings	[2]	1,301	1,304	3,901	3,913
Post-Retirement Benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance beginning		5,570	4,915	5,764	5,264
Other comprehensive income		(98)	(174)	(292)	(523)
Balance ending		5,472	4,741	5,472	4,741
Amortization of Prior Service Credits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassifications to earnings	[2]	0	(100)	0	(300)
Amortization of Net (Gain) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassifications to earnings	[2]	$ (98)	$ (74)	$ (292)	$ (223)

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