Summary of Significant Accounting Policies - Goodwill and Intangible Assets (Details) - USD ($)	3 Months Ended		12 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Goodwill [Line Items]
Impairment of goodwill			$ 656,000,000	$ 0	$ 0
Goodwill	$ 3,027,000,000		3,027,000,000	3,612,000,000	3,770,000,000
Accumulated impairment losses	656,000,000		656,000,000	0
AmeriGas Propane
Goodwill [Line Items]
Impairment of goodwill	656,000,000	$ 656,000,000	656,000,000
Goodwill	1,348,000,000		1,348,000,000	$ 2,004,000,000	$ 2,004,000,000
Accumulated impairment losses	$ 656,000,000		$ 656,000,000
UGI International
Goodwill [Line Items]
Fair value in excess of carrying value	10.00%		10.00%
Goodwill	$ 911,000,000		$ 911,000,000