Summary of Significant Accounting Policies - Narrative (Details) - USD ($)	3 Months Ended			9 Months Ended
	Jun. 30, 2023	Sep. 30, 2022	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	May 31, 2023
Schedule of Equity Method Investments [Line Items]
Impairment of goodwill	$ 656,000,000		$ 0	$ 656,000,000	$ 0
Goodwill	3,060,000,000	$ 3,612,000,000	3,671,000,000	3,060,000,000	3,671,000,000
AmeriGas Propane
Schedule of Equity Method Investments [Line Items]
Impairment of goodwill	656,000,000
Goodwill	$ 1,300,000,000			$ 1,300,000,000
AmeriGas Partners And AmeriGas Finance Corp. | Senior Notes Due 2028 | Senior Notes
Schedule of Equity Method Investments [Line Items]
Principal amount						$ 500,000,000
Interest rate						9.375%
Pennant | Energy Services
Schedule of Equity Method Investments [Line Items]
Equity interest acquired		53.00%
Purchase price		$ 61,000,000
MBL Bioenergy
Schedule of Equity Method Investments [Line Items]
Equity method investment ownership percent	99.99%			99.99%
Equity method investments	$ 93,000,000		0	$ 93,000,000	0
Pine Run Midstream, LLC
Schedule of Equity Method Investments [Line Items]
Equity method investment ownership percent	49.00%			49.00%
Equity method investments	$ 75,000,000		67,000,000	$ 75,000,000	67,000,000
Pennant | Energy Services
Schedule of Equity Method Investments [Line Items]
Equity method investment ownership percent	47.00%			47.00%
Equity method investments			49,000,000		49,000,000
Other equity method investments				$ 50,000,000
Other equity method investments
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 84,000,000		$ 44,000,000	$ 84,000,000	$ 44,000,000