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. 27, 2015	Jun. 28, 2014
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	$ 1,512	$ 1,847
Beginning balance realized during the period	(1,325)	(773)
Contracts purchased during the period	1,499	1,141
Change in the fair value of outstanding contracts	1,741	(85)
Ending balance of over-the-counter options	3,427	2,130
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	0	0
Beginning balance realized during the period	0	0
Contracts purchased during the period	265	0
Change in the fair value of outstanding contracts	0	0
Ending balance of over-the-counter options	$ 265	$ 0