Summary of Significant Accounting Policies (Details) $ in Thousands	12 Months Ended
	Sep. 26, 2020 USD ($) wk Partnership shares	Sep. 28, 2019 shares	Sep. 29, 2018 shares	Sep. 29, 2019 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Minimum number of weeks in the fiscal year reporting calendar	52
Maximum number of weeks in the fiscal year reporting calendar	53
Minimum number of weeks in a fiscal quarter	13
Maximum number of weeks in a fiscal quarter	14
Goodwill and Intangible Assets Disclosure [Abstract]
Projection period for discounted cash flow analyses to estimate reporting unit fair value	10 years
Income Taxes [Abstract]
Number of limited partnerships included in the partnership structure | Partnership	2
Net Income Per Unit [Abstract]
Increase in weighted average units outstanding used to compute basic net income per Common Unit to reflect the potential dilutive effect of the unvested restricted units outstanding (in units) | shares	427,504	373,370	290,020
Assets and Liabilities, Lessee [Abstract]
Operating Lease, Right-of-Use Asset | $	$ 119,594			$ 103,100
Operating Lease, Liability | $	$ 119,104			$ 103,100
Storage facilities [Member] | Weighted Average [Member]
Property, Plant and Equipment [Abstract]
Estimated useful life of the asset (in years)	23 years
Storage facilities [Member] | Minimum [Member]
Property, Plant and Equipment [Abstract]
Estimated useful life of the asset (in years)	7 years
Storage facilities [Member] | Maximum [Member]
Property, Plant and Equipment [Abstract]
Estimated useful life of the asset (in years)	30 years
Tanks and cylinders [Member} | Weighted Average [Member]
Property, Plant and Equipment [Abstract]
Estimated useful life of the asset (in years)	28 years
Tanks and cylinders [Member} | Minimum [Member]
Property, Plant and Equipment [Abstract]
Estimated useful life of the asset (in years)	10 years
Tanks and cylinders [Member} | Maximum [Member]
Property, Plant and Equipment [Abstract]
Estimated useful life of the asset (in years)	40 years
Federal Funds Rate [Member]
Interest Rate Risk [Abstract]
Description of applicable interest rate on borrowings	Federal Funds Rate
Basis spread (in hundredths)	0.50%
LIBOR [Member]
Interest Rate Risk [Abstract]
Description of applicable interest rate on borrowings	LIBOR
Basis spread (in hundredths)	1.00%
Suburban Propane Partners, L.P. [Member]
Summary Of Significant Accounting Policies [Line Items]
Limited partner interest in the Operating Partnership (in hundredths)	100.00%