Segment Information - Schedule of Segment Reporting Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Sep. 30, 2023
Segment Reporting Information [Line Items]
Revenues	$ 1,380	$ 1,659	$ 5,968	$ 7,524
Cost of sales	639	1,104	2,871	6,358
Operating income (loss)	67	(732)	1,016	(1,681)
(Loss) income from equity investees	(24)	1	(22)	2
Loss on extinguishments of debt	(7)	(9)	(7)	(9)
Other non-operating income (expense), net	5	1	3	(25)
Earnings (loss) before interest expense and income taxes	41	(739)	990	(1,713)
Interest expense	(96)	(96)	(296)	(281)
(Loss) income before income taxes	(55)	(835)	694	(1,994)
Depreciation and amortization	139	134	414	397
Capital expenditures (including the effects of accruals)	211	255	511	647
Total assets	15,066	15,243	15,066	15,243	$ 15,401
Eliminations
Segment Reporting Information [Line Items]
Revenues	(28)	(25)	(239)	(302)
Cost of sales	(28)	(26)	(239)	(301)
Operating income (loss)	0	0	0	0
(Loss) income from equity investees	0	0	0	0
Loss on extinguishments of debt	0	0	0	0
Other non-operating income (expense), net	0	0	0	0
Earnings (loss) before interest expense and income taxes	0	0	0	0
Interest expense	0	0	0	0
(Loss) income before income taxes	0	0	0	0
Depreciation and amortization	0	0	0	0
Capital expenditures (including the effects of accruals)	0	0	0	0
Total assets	(143)	(182)	(143)	(182)
Eliminations | Utilities
Segment Reporting Information [Line Items]
Revenues	7	8	43	69
Eliminations | Midstream & Marketing
Segment Reporting Information [Line Items]
Revenues	22	19	197	232
Eliminations | UGI International
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Eliminations | AmeriGas Propane
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Operating Segments | Utilities
Segment Reporting Information [Line Items]
Revenues	257	278	1,396	1,644
Revenues from external customers	250	270	1,353	1,575
Cost of sales	89	118	584	873
Operating income (loss)	37	32	396	361
(Loss) income from equity investees	0	0	0	0
Loss on extinguishments of debt	0	0	0	0
Other non-operating income (expense), net	2	2	4	6
Earnings (loss) before interest expense and income taxes	39	34	400	367
Interest expense	(22)	(20)	(69)	(62)
(Loss) income before income taxes	17	14	331	305
Depreciation and amortization	42	38	124	112
Capital expenditures (including the effects of accruals)	126	146	299	396
Total assets	5,792	5,560	5,792	5,560
Operating Segments | Midstream & Marketing
Segment Reporting Information [Line Items]
Revenues	253	279	1,130	1,586
Revenues from external customers	231	260	933	1,354
Cost of sales	167	192	689	1,185
Operating income (loss)	41	40	291	249
(Loss) income from equity investees	2	1	7	4
Loss on extinguishments of debt	0	0	0	0
Other non-operating income (expense), net	0	0	0	0
Earnings (loss) before interest expense and income taxes	43	41	298	253
Interest expense	(9)	(11)	(29)	(33)
(Loss) income before income taxes	34	30	269	220
Depreciation and amortization	22	22	66	65
Capital expenditures (including the effects of accruals)	40	40	92	74
Total assets	3,182	3,050	3,182	3,050
Operating Segments | UGI International
Segment Reporting Information [Line Items]
Revenues	455	611	1,853	2,436
Cost of sales	244	418	1,058	1,713
Operating income (loss)	57	21	294	197
(Loss) income from equity investees	(1)	0	(4)	(2)
Loss on extinguishments of debt	0	0	0	0
Other non-operating income (expense), net	1	1	15	21
Earnings (loss) before interest expense and income taxes	57	22	305	216
Interest expense	(11)	(10)	(33)	(26)
(Loss) income before income taxes	46	12	272	190
Depreciation and amortization	29	30	88	86
Capital expenditures (including the effects of accruals)	24	27	55	84
Total assets	2,807	3,179	2,807	3,179
Operating Segments | AmeriGas Propane
Segment Reporting Information [Line Items]
Revenues	445	514	1,869	2,147
Cost of sales	217	251	862	1,067
Operating income (loss)	(27)	(8)	182	240
(Loss) income from equity investees	0	0	0	0
Loss on extinguishments of debt	0	0	0	0
Other non-operating income (expense), net	0	0	0	0
Earnings (loss) before interest expense and income taxes	(27)	(8)	182	240
Interest expense	(41)	(40)	(122)	(122)
(Loss) income before income taxes	(68)	(48)	60	118
Depreciation and amortization	46	43	134	132
Capital expenditures (including the effects of accruals)	21	42	65	93
Total assets	3,228	3,443	3,228	3,443
Corporate & Other
Segment Reporting Information [Line Items]
Revenues from external customers	(1)	4	(40)	12
Cost of sales	(50)	151	(83)	1,821
Operating income (loss)	(41)	(817)	(147)	(2,728)
(Loss) income from equity investees	(25)	0	(25)	0
Loss on extinguishments of debt	(7)	(9)	(7)	(9)
Other non-operating income (expense), net	2	(2)	(16)	(52)
Earnings (loss) before interest expense and income taxes	(71)	(828)	(195)	(2,789)
Interest expense	(13)	(15)	(43)	(38)
(Loss) income before income taxes	(84)	(843)	(238)	(2,827)
Depreciation and amortization	0	1	2	2
Capital expenditures (including the effects of accruals)	0	0	0	0
Total assets	200	193	200	193
Corporate & Other | Midstream & Marketing
Segment Reporting Information [Line Items]
Loss on extinguishments of debt	(1)	0	(1)	0
Corporate & Other | UGI International
Segment Reporting Information [Line Items]
Loss on extinguishments of debt	0	0	0	0
Corporate & Other | AmeriGas Propane
Segment Reporting Information [Line Items]
Loss on extinguishments of debt	(6)	(9)	(6)	(9)
Intersegment revenues Corporate & Other
Segment Reporting Information [Line Items]
Revenues	$ (1)	$ (2)	$ (1)	$ 1