Business Combinations and Divestitures - Additional Information (Detail) $ in Millions			3 Months Ended
	Dec. 31, 2020 USD ($) PartnershipUnit	Oct. 27, 2020 USD ($)	Dec. 31, 2019 USD ($)
Propane Dealers
Business Acquisition [Line Items]
Number of businesses acquired | PartnershipUnit	2
Aggregate purchase price partnership acquired	$ 37.9
Cash paid	37.1
Deferred liabilities	0.8
Aggregate purchase price allocation, intangible assets	32.7
Aggregate purchase price allocation, fixed assets	5.5
Gross purchase price increased (reduced) by working capital credits	$ (0.3)
Acquired Business
Business Acquisition [Line Items]
Aggregate purchase price partnership acquired			$ 0.5
Propane Assets
Business Acquisition [Line Items]
Cash proceeds from sale of assets		$ 6.1