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	12 Months Ended
	Sep. 26, 2015	Sep. 27, 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	(1,450)	(1,166)
Contracts purchased during the period	2,067	1,145
Change in the fair value of outstanding contracts	652	(314)
Ending balance of over-the-counter options	2,781	1,512
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	347	0
Change in the fair value of outstanding contracts	0	0
Ending balance of over-the-counter options	$ 347	$ 0