Fair Value Measurements - Narrative (Details) - USD ($)	3 Months Ended		12 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Impairment of goodwill			$ 656,000,000	$ 0	$ 0
AmeriGas Propane
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Impairment of goodwill	$ 656,000,000	$ 656,000,000	656,000,000
Level 3 | Commodity contracts | Minimum
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Unobservable inputs reconciliation	7,000,000		7,000,000
Level 3 | Commodity contracts | Maximum
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Unobservable inputs reconciliation	$ 27,000,000		$ 27,000,000