Summary of Significant Accounting Policies - Additional Information (Detail)				12 Months Ended
	Aug. 31, 2022 USD ($)	Aug. 31, 2021 USD ($)	Aug. 31, 2020 USD ($)	Sep. 30, 2022 USD ($) Segment	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)
Schedule Of Significant Accounting Policies [Line Items]
Cash, cash equivalents, and restricted cash				$ 14,870,000	$ 5,017,000	$ 57,161,000	$ 5,149,000
Cash and cash equivalents				14,620,000	4,767,000
Restricted cash				$ 250,000	250,000
Number of reportable segments | Segment				1
Goodwill impairment	$ 0	$ 0	$ 0
Minimum percentage of likelihood on goodwill impairment		50.00%
Other income (loss)						(5,724,000)
Advertising expenses				$ 13,000,000.0	13,500,000	$ 13,500,000
Description of uncertain tax position				greater than 50%
Derivative maximum payout				$ 5,000,000.0
Delivery and branch expense reduced under weather hedge contract				1,100,000	$ 3,400,000
Propane Assets
Schedule Of Significant Accounting Policies [Line Items]
Loss on sale of assets held for sale				(5,700,000)
Propane Assets | Goodwill
Schedule Of Significant Accounting Policies [Line Items]
Assets held-for-sale				2,200,000
Propane Assets | Property and Equipment, Net
Schedule Of Significant Accounting Policies [Line Items]
Assets held-for-sale				$ 800,000
Maximum
Schedule Of Significant Accounting Policies [Line Items]
Cash equivalents, highly liquid investments maturity				3 months
Derivative maximum receivable				$ 12,500,000
Maximum | Customer Lists
Schedule Of Significant Accounting Policies [Line Items]
Intangible assets, amortization period				10 years
Maximum | Trade Names
Schedule Of Significant Accounting Policies [Line Items]
Intangible assets, amortization period				20 years
Maximum | Land Improvements
Schedule Of Significant Accounting Policies [Line Items]
Property and equipment, estimated useful lives				20 years
Maximum | Buildings and leasehold improvements
Schedule Of Significant Accounting Policies [Line Items]
Property and equipment, estimated useful lives				30 years
Maximum | Fleet and Other Equipment
Schedule Of Significant Accounting Policies [Line Items]
Property and equipment, estimated useful lives				15 years
Maximum | Tanks and Equipment
Schedule Of Significant Accounting Policies [Line Items]
Property and equipment, estimated useful lives				10 years
Maximum | Furniture, Fixtures and Office Equipment
Schedule Of Significant Accounting Policies [Line Items]
Property and equipment, estimated useful lives				10 years
Minimum | Customer Lists
Schedule Of Significant Accounting Policies [Line Items]
Intangible assets, amortization period				7 years
Minimum | Trade Names
Schedule Of Significant Accounting Policies [Line Items]
Intangible assets, amortization period				3 years
Minimum | Land Improvements
Schedule Of Significant Accounting Policies [Line Items]
Property and equipment, estimated useful lives				10 years
Minimum | Buildings and leasehold improvements
Schedule Of Significant Accounting Policies [Line Items]
Property and equipment, estimated useful lives				5 years
Minimum | Fleet and Other Equipment
Schedule Of Significant Accounting Policies [Line Items]
Property and equipment, estimated useful lives				1 year
Minimum | Tanks and Equipment
Schedule Of Significant Accounting Policies [Line Items]
Property and equipment, estimated useful lives				3 years
Minimum | Furniture, Fixtures and Office Equipment
Schedule Of Significant Accounting Policies [Line Items]
Property and equipment, estimated useful lives				5 years