Summary of Significant Accounting Policies - Goodwill and Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Goodwill [Line Items]
Goodwill	$ 2,871	$ 3,027	$ 3,612
Impairment of goodwill	195	656	0
Accumulated goodwill impairment	851	656
UGI International
Goodwill [Line Items]
Goodwill	950	911	840
Impairment of goodwill	0	0
AmeriGas Propane
Goodwill [Line Items]
Goodwill	1,153	1,348	$ 2,004
Impairment of goodwill	$ 195	$ 656
UGI International
Goodwill [Line Items]
Fair value in excess of carrying value		30.00%