Employee Retirement Plans - Change in Pension Benefits and Other Postretirement Benefits Obligations (Details) - Pension Benefits - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Change in benefit obligations:
Benefit obligations — beginning of year	$ 870	$ 782
Service cost	16	12	$ 11
Interest cost	26	22	23
Actuarial gain	(240)	(30)
Plan amendments	1	2
Acquisitions	0	114
Foreign currency	(6)	(1)
Benefits paid	(34)	(31)
Benefit obligations — end of year	633	870	782
Change in plan assets:
Fair value of plan assets — beginning of year	736	585
Actual (loss) gain on plan assets	(173)	75
Foreign currency	(3)	0
Employer contributions	15	14
Acquisitions	0	92
Benefits paid	(34)	(30)
Fair value of plan assets — end of year	541	736	$ 585
Funded status of the plans — end of year	(92)	(134)
Amounts recorded in UGI Corporation stockholders’ equity (pre-tax):
Prior service cost	3	3
Net actuarial (gain) loss	(17)	13
Total	(14)	16
Amounts recorded in regulatory assets and liabilities (pre-tax):
Net actuarial loss	114	108
Total	114	108
ABO for the pension plans	$ 570	$ 756