Employee Retirement Plans - Fair Value of U.S. Pension Plan and VEBA Trust Assets (Details) - Pension Benefits - USD ($) $ in Millions	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 556	$ 541	$ 736
U.S.
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	539	525
U.S. | U.S. equities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	19	26
U.S. | UGI Corporation Common Stock
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	19	26
U.S. | Total common collective trust funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	503	482
U.S. | U.S. equity index investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	120	113
U.S. | Non-U.S. equity index investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	117	110
U.S. | Global equity index investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	75	72
U.S. | Bond index mutual funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	183	177
U.S. | Cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	8	10
U.S. | Alternative investments
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 17	$ 17