Pension Plans and Other Postretirement Benefits - Components of Net Periodic Benefit Costs (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 26, 2015	Dec. 27, 2014
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 1,260	$ 1,282
Expected return on plan assets	(854)	(1,228)
Amortization of net loss (gain)	1,134	1,130
Net periodic benefit cost	1,540	1,184
Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	130	144
Amortization of prior service credits	(100)	(122)
Amortization of net loss (gain)	(75)	(49)
Net periodic benefit cost	$ (45)	$ (27)