Financial Instruments and Risk Management - Reconciliation of the Beginning and Ending Balances of Assets and Liabilities Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 30, 2017	Dec. 24, 2016
Reconciliation of beginning and ending balances of assets measured at fair value on recurring basis using significant unobservable inputs [Rollforward]
Beginning balance of over-the-counter options	$ 4,108	$ 809
Beginning balance realized during the period	(313)	0
Contracts purchased during the period	0	48
Change in the fair value of outstanding contracts	122	332
Ending balance of over-the-counter options	3,917	1,189
Reconciliation of beginning and ending balances of liabilities measured at fair value on recurring basis using significant unobservable inputs [Rollforward]
Beginning balance of over-the-counter options	737	0
Beginning balance realized during the period	0	0
Contracts purchased during the period	0	0
Change in the fair value of outstanding contracts	(305)	0
Ending balance of over-the-counter options	$ 432	$ 0