Segment Information - Schedule of Segment Reporting Information (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Sep. 30, 2024
Segment Reporting Information [Line Items]
Revenues	$ 2,030	$ 2,121
Cost of sales	923	1,202
Operating income (loss)	487	232
Income (loss) from equity investees	3	1
Other non-operating income (expense), net	29	(13)
Earnings (loss) before interest expense and income taxes	519	220
Interest expense	(102)	(100)
Income before income taxes	417	120
Depreciation and amortization	138	137
Capital expenditures (including the effects of accruals)	175	133
Total assets	15,412	15,716	$ 15,098
Eliminations
Segment Reporting Information [Line Items]
Revenues	(86)	(80)
Cost of sales	(86)	(80)
Operating income (loss)	1	(1)
Income (loss) from equity investees	0	0
Other non-operating income (expense), net	0	0
Earnings (loss) before interest expense and income taxes	1	(1)
Interest expense	0	0
Income before income taxes	1	(1)
Depreciation and amortization	0	0
Capital expenditures (including the effects of accruals)	0	0
Total assets	(220)	(190)
Eliminations | Utilities
Segment Reporting Information [Line Items]
Revenues	15	13
Eliminations | Midstream & Marketing
Segment Reporting Information [Line Items]
Revenues	71	67
Eliminations | UGI International
Segment Reporting Information [Line Items]
Revenues	0	0
Eliminations | AmeriGas Propane
Segment Reporting Information [Line Items]
Revenues	0	0
Operating Segments | Utilities
Segment Reporting Information [Line Items]
Revenues	485	493
Revenues from external customers	470	480
Cost of sales	204	221
Operating income (loss)	138	134
Income (loss) from equity investees	0	0
Other non-operating income (expense), net	3	1
Earnings (loss) before interest expense and income taxes	141	135
Interest expense	(26)	(23)
Income before income taxes	115	112
Depreciation and amortization	44	41
Capital expenditures (including the effects of accruals)	106	82
Total assets	6,183	5,855
Operating Segments | Midstream & Marketing
Segment Reporting Information [Line Items]
Revenues	367	394
Revenues from external customers	296	327
Cost of sales	229	239
Operating income (loss)	91	99
Income (loss) from equity investees	4	3
Other non-operating income (expense), net	0	0
Earnings (loss) before interest expense and income taxes	95	102
Interest expense	(12)	(11)
Income before income taxes	83	91
Depreciation and amortization	20	22
Capital expenditures (including the effects of accruals)	32	19
Total assets	3,321	3,236
Operating Segments | UGI International
Segment Reporting Information [Line Items]
Revenues	638	725
Cost of sales	374	446
Operating income (loss)	106	113
Income (loss) from equity investees	(1)	(2)
Other non-operating income (expense), net	5	6
Earnings (loss) before interest expense and income taxes	110	117
Interest expense	(10)	(11)
Income before income taxes	100	106
Depreciation and amortization	29	30
Capital expenditures (including the effects of accruals)	14	12
Total assets	2,835	3,150
Operating Segments | AmeriGas Propane
Segment Reporting Information [Line Items]
Revenues	627	629
Cost of sales	280	283
Operating income (loss)	74	71
Income (loss) from equity investees	0	0
Other non-operating income (expense), net	0	0
Earnings (loss) before interest expense and income taxes	74	71
Interest expense	(33)	(41)
Income before income taxes	41	30
Depreciation and amortization	45	44
Capital expenditures (including the effects of accruals)	23	20
Total assets	3,082	3,460
Corporate & Other
Segment Reporting Information [Line Items]
Revenues from external customers	(1)	(40)
Cost of sales	(78)	93
Operating income (loss)	77	(184)
Income (loss) from equity investees	0	0
Other non-operating income (expense), net	21	(20)
Earnings (loss) before interest expense and income taxes	98	(204)
Interest expense	(21)	(14)
Income before income taxes	77	(218)
Depreciation and amortization	0	0
Capital expenditures (including the effects of accruals)	0	0
Total assets	211	205
Intersegment revenues Corporate & Other
Segment Reporting Information [Line Items]
Revenues	$ 0	$ 0