Financial Instruments and Risk Management - Effect of the Partnership's Derivative Instruments on the Consolidated Statements of Operations (Details) - USD ($) $ in Thousands	12 Months Ended
Sep. 26, 2020	Sep. 28, 2019	Sep. 29, 2018
Commodity-Related Derivatives [Member] \| Cost of Products Sold [Member] \| Derivatives Not Designated as Hedging Instruments [Member]
Derivative Instruments Gain Loss [Line Items]
Unrealized (Losses) Gains Recognized in Income	$ (381)	$ (8,008)	$ 310

Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5618551-113959

Name:	us-gaap_DerivativeGainLossOnDerivativeNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration