Pension Plans and Other Postretirement Benefits - Components of Net Periodic Benefit Costs (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 25, 2016	Jun. 27, 2015	Jun. 25, 2016	Jun. 27, 2015
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 1,260	$ 1,282	$ 3,781	$ 3,846
Expected return on plan assets	(854)	(1,228)	(2,563)	(3,685)
Amortization of net loss (gain)	1,304	1,131	3,913	3,392
Net periodic benefit cost (income)	1,710	1,185	5,131	3,553
Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	130	144	400	431
Amortization of prior service credits	(100)	(122)	(300)	(367)
Amortization of net loss (gain)	(74)	(49)	(223)	(147)
Net periodic benefit cost (income)	$ (44)	$ (27)	$ (123)	$ (83)