Pension Plans and Other Postretirement Benefits - Components of Net Periodic Benefit Costs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2018	Mar. 25, 2017	Mar. 31, 2018	Mar. 25, 2017
Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 69	$ 96	$ 138	$ 193
Amortization of prior service credits	(124)	0	(248)	0
Amortization of net loss (gain)	(164)	(97)	(328)	(194)
Net periodic benefit cost	(219)	(1)	(438)	(1)
Pension Benefits [Member] | United States [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	944	1,041	1,888	2,082
Expected return on plan assets	(473)	(537)	(947)	(1,075)
Amortization of net loss (gain)	921	1,300	1,842	2,600
Net periodic benefit cost	$ 1,392	$ 1,804	$ 2,783	$ 3,607