Financial Instruments and Risk Management - Fair Value of the Partnership's Derivative Instruments and their Location in the Condensed Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Sep. 24, 2016
Derivatives, Fair Value [Line Items]
Fair value - assets	$ 16,378	$ 7,072
Fair value - liabilities	6,853	4,780
Commodity-Related Derivatives [Member]
Derivatives, Fair Value [Line Items]
Fair value - assets	16,378	6,842
Fair value - liabilities	6,853	4,345
Interest Rate Swaps [Member]
Derivatives, Fair Value [Line Items]
Fair value - assets		230
Fair value - liabilities		435
Derivatives Not Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Fair value - assets	11,935	4,852
Fair value - liabilities	2,410	2,355
Derivatives Not Designated as Hedging Instruments [Member] | Commodity-Related Derivatives [Member] | Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Fair value - assets	11,164	3,306
Derivatives Not Designated as Hedging Instruments [Member] | Commodity-Related Derivatives [Member] | Other Assets [Member]
Derivatives, Fair Value [Line Items]
Fair value - assets	771	1,546
Derivatives Not Designated as Hedging Instruments [Member] | Commodity-Related Derivatives [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value - liabilities	1,978	1,002
Derivatives Not Designated as Hedging Instruments [Member] | Commodity-Related Derivatives [Member] | Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value - liabilities	432	1,353
Derivatives Designated as Hedging Instruments [Member]
Derivatives, Fair Value [Line Items]
Fair value - liabilities	0	205
Derivatives Designated as Hedging Instruments [Member] | Interest Rate Swaps [Member] | Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Fair value - liabilities	$ 0	$ 205