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	9 Months Ended
	Jun. 25, 2016	Jun. 27, 2015
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	$ 2,781	$ 1,512
Beginning balance realized during the period	(2,546)	(1,325)
Contracts purchased during the period	762	1,499
Change in the fair value of outstanding contracts	(234)	1,741
Ending balance of over-the-counter options	763	3,427
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	347	0
Beginning balance realized during the period	(275)	0
Contracts purchased during the period	0	265
Change in the fair value of outstanding contracts	(72)	0
Ending balance of over-the-counter options	$ 0	$ 265