Employee Benefit Plans - Schedule of Net Benefit Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 24, 2016	Sep. 26, 2015	Sep. 27, 2014
Components of net periodic benefit costs included in operating expenses [Abstract]
Settlement charge	$ (2,000)	$ (2,000)	$ 0
Pension Benefits [Member]
Components of net periodic benefit costs included in operating expenses [Abstract]
Interest cost	5,041	5,128	5,774
Expected return on plan assets	(3,418)	(4,913)	(5,102)
Amortization of prior service credit	0	0	0
Settlement charge	2,000	2,000	0
Recognized net actuarial loss (gain)	5,218	4,522	4,492
Net periodic benefit costs	8,841	6,737	5,164
Retiree Health and Life Benefits [Member]
Components of net periodic benefit costs included in operating expenses [Abstract]
Interest cost	520	575	645
Expected return on plan assets	0	0	0
Amortization of prior service credit	(399)	(490)	(490)
Settlement charge	0	0	0
Recognized net actuarial loss (gain)	(299)	(196)	(181)
Net periodic benefit costs	$ (178)	$ (111)	$ (26)