Pension Plans and Other Postretirement Benefits - Components of Net Periodic Benefit Costs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 26, 2016	Mar. 28, 2015	Mar. 26, 2016	Mar. 28, 2015
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 1,260	$ 1,282	$ 2,521	$ 2,564
Expected return on plan assets	(854)	(1,228)	(1,709)	(2,457)
Amortization of net loss (gain)	1,475	1,131	2,609	2,261
Net periodic benefit cost	1,881	1,185	3,421	2,368
Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	130	143	260	288
Amortization of prior service credits	(100)	(123)	(200)	(245)
Amortization of net loss (gain)	(74)	(49)	(149)	(98)
Net periodic benefit cost	$ (44)	$ (29)	$ (89)	$ (55)