Debt - Schedule of Long-term Debt Instruments (Details) - USD ($) $ in Millions	Sep. 30, 2025	Sep. 30, 2024	Jun. 30, 2024
Debt Instrument [Line Items]
Total long-term debt	$ 6,648	$ 6,678
Less: current maturities	(117)	(235)
Total long-term debt due after one year	6,531	6,443
UGI Utilities, Inc.
Debt Instrument [Line Items]
Unamortized debt issuance costs	(7)	(7)
Total long-term debt	2,124	1,889
Midstream & Marketing
Debt Instrument [Line Items]
Unamortized debt issuance costs	(11)	(13)
Total long-term debt	807	814
UGI International
Debt Instrument [Line Items]
Unamortized debt issuance costs	(5)	(6)
Total long-term debt	829	787
AmeriGas Propane
Debt Instrument [Line Items]
Unamortized debt issuance costs	(14)	(10)
Total long-term debt	1,741	1,877
UGI Corporation
Debt Instrument [Line Items]
Unamortized debt issuance costs	(16)	(19)
Total long-term debt	1,347	1,311
UGI Corporation | Eliminations
Debt Instrument [Line Items]
Total long-term debt	$ (200)	0
4.12% due September 2046 | UGI Utilities, Inc. | Senior Notes
Debt Instrument [Line Items]
Interest rate (as a percentage)	4.12%
Long-term debt, gross	$ 200	200
4.98% due March 2044 | UGI Utilities, Inc. | Senior Notes
Debt Instrument [Line Items]
Interest rate (as a percentage)	4.98%
Long-term debt, gross	$ 175	175
3.12% due April 2050 | UGI Utilities, Inc. | Senior Notes
Debt Instrument [Line Items]
Interest rate (as a percentage)	3.12%
Long-term debt, gross	$ 150	150
4.55% due February 2049 | UGI Utilities, Inc. | Senior Notes
Debt Instrument [Line Items]
Interest rate (as a percentage)	4.55%
Long-term debt, gross	$ 150	150
4.12% due October 2046 | UGI Utilities, Inc. | Senior Notes
Debt Instrument [Line Items]
Interest rate (as a percentage)	4.12%
Long-term debt, gross	$ 100	100
6.21% due September 2036 | UGI Utilities, Inc. | Senior Notes
Debt Instrument [Line Items]
Interest rate (as a percentage)	6.21%
Long-term debt, gross	$ 100	100
2.95% due June 2026 | UGI Utilities, Inc. | Senior Notes
Debt Instrument [Line Items]
Interest rate (as a percentage)	2.95%
Long-term debt, gross	$ 100	100
1.59% due June 2026 | UGI Utilities, Inc. | Senior Notes
Debt Instrument [Line Items]
Interest rate (as a percentage)	1.59%
Long-term debt, gross	$ 100	100
1.64% due September 2026 | UGI Utilities, Inc. | Senior Notes
Debt Instrument [Line Items]
Interest rate (as a percentage)	1.64%
Long-term debt, gross	$ 75	75
4.75% due July 2032 | UGI Utilities, Inc. | Senior Notes
Debt Instrument [Line Items]
Interest rate (as a percentage)	4.75%
Long-term debt, gross	$ 90	90
4.99% due September 2052 | UGI Utilities, Inc. | Senior Notes
Debt Instrument [Line Items]
Interest rate (as a percentage)	4.99%
Long-term debt, gross	$ 85	85
6.02% due November 2030 | UGI Utilities, Inc. | Senior Notes
Debt Instrument [Line Items]
Interest rate (as a percentage)	6.02%
Long-term debt, gross	$ 25	25
6.10% due November 2033 | UGI Utilities, Inc. | Senior Notes
Debt Instrument [Line Items]
Interest rate (as a percentage)	6.10%
Long-term debt, gross	$ 150	150
6.40% due November 2053 | UGI Utilities, Inc. | Senior Notes
Debt Instrument [Line Items]
Interest rate (as a percentage)	6.40%
Long-term debt, gross	$ 75	75
5.24% due November 2029 | UGI Utilities, Inc. | Senior Notes
Debt Instrument [Line Items]
Interest rate (as a percentage)	5.24%
Long-term debt, gross	$ 50	0
5.52% due November 2034 | UGI Utilities, Inc. | Senior Notes
Debt Instrument [Line Items]
Interest rate (as a percentage)	5.52%
Long-term debt, gross	$ 125	0
6.13% due October 2034 | UGI Utilities, Inc. | Medium-Term Note
Debt Instrument [Line Items]
Interest rate (as a percentage)	6.13%
Long-term debt, gross	$ 20	20
6.50% due August 2033 | UGI Utilities, Inc. | Medium-Term Note
Debt Instrument [Line Items]
Interest rate (as a percentage)	6.50%
Long-term debt, gross	$ 20	20
Mountaineer senior notes | UGI Utilities, Inc. | Senior Notes
Debt Instrument [Line Items]
Long-term debt, gross	264	196
Variable-rate term loan | UGI Utilities, Inc. | Term Loan
Debt Instrument [Line Items]
Long-term debt, gross	76	83
Variable-rate term loan | Midstream & Marketing | Term Loan
Debt Instrument [Line Items]
Long-term debt, gross	778	786
Variable-rate term loan | UGI International | Term Loan Due March 2028
Debt Instrument [Line Items]
Long-term debt, gross	352	335
Other | UGI Utilities, Inc. | Other
Debt Instrument [Line Items]
Long-term debt, gross	1	2
Other | Midstream & Marketing | Other
Debt Instrument [Line Items]
Long-term debt, gross	40	41
Other | UGI International | Other
Debt Instrument [Line Items]
Long-term debt, gross	13	12
Other | AmeriGas Propane
Debt Instrument [Line Items]
Long-term debt, gross	$ 200	0
2.50% Senior Notes due December 2029 | UGI International | Senior Notes
Debt Instrument [Line Items]
Interest rate (as a percentage)	2.50%
Long-term debt, gross	$ 469	446
5.50% due May 2025 | AmeriGas Propane | Senior Notes
Debt Instrument [Line Items]
Interest rate (as a percentage)	5.50%
Long-term debt, gross	$ 0	218
5.875% due August 2026 | AmeriGas Propane | Senior Notes
Debt Instrument [Line Items]
Interest rate (as a percentage)	5.875%
Long-term debt, gross	$ 0	664
5.75% due May 2027 | AmeriGas Propane | Senior Notes
Debt Instrument [Line Items]
Interest rate (as a percentage)	5.75%
Long-term debt, gross	$ 512	512
9.375% due June 2028 | AmeriGas Propane | Senior Notes
Debt Instrument [Line Items]
Interest rate (as a percentage)	9.375%
Long-term debt, gross	$ 493	493
9.50% due June 2030 | AmeriGas Propane | Senior Notes
Debt Instrument [Line Items]
Interest rate (as a percentage)	9.50%
Long-term debt, gross	$ 550	0
Credit Facility Maturing August 2025 | UGI Corporation | Line of Credit
Debt Instrument [Line Items]
Long-term debt, gross	0	115
Credit Facility Maturing October 2028 | UGI Corporation | Line of Credit
Debt Instrument [Line Items]
Long-term debt, gross	263	0
3-year Term loan | UGI Corporation | Term Loan
Debt Instrument [Line Items]
Long-term debt, gross	0	300
5-year Term Loan | UGI Corporation | Term Loan
Debt Instrument [Line Items]
Long-term debt, gross	0	215
Due October | UGI Corporation | Term Loan
Debt Instrument [Line Items]
Long-term debt, gross	400	0
UGI Corporation Senior Notes | Senior Notes
Debt Instrument [Line Items]
Interest rate (as a percentage)			5.00%
UGI Corporation Senior Notes | UGI Corporation | Senior Notes
Debt Instrument [Line Items]
Long-term debt, gross	$ 700	$ 700