Employee Retirement Plans - Fair Value of U.S. Pension Plan and VEBA Trust Assets (Details) - Pension Benefits - USD ($) $ in Millions	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 657	$ 556	$ 541
U.S.
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	635	539
Equity investments | U.S.
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	20	19
UGI Corporation Common Stock | U.S.
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	20	19
Total common collective trust funds | U.S.
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	598	503
U.S. equity index investments | U.S.
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	188	120
Non-U.S. equity index investments | U.S.
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	96	117
Global equity index investments | U.S.
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	29	75
Bond index mutual funds | U.S.
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	274	183
Cash equivalents | U.S.
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	11	8
Alternative investments | U.S.
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 17	$ 17