Segment Information - Schedule of Segment Reporting Information (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Sep. 30, 2023
Segment Reporting Information [Line Items]
Revenues	$ 2,121	$ 2,759
Cost of sales	1,202	3,106
Operating income (loss)	232	(1,204)
Income (loss) from equity investees	1	1
Other non-operating (loss) income, net	(13)	(28)
(Loss) earnings before interest expense and income taxes	220	(1,231)
Interest expense	(100)	(92)
Income (loss) before income taxes	120	(1,323)
Depreciation and amortization	137	131
Capital expenditures (including the effects of accruals)	133	178
Total assets	15,716	17,128	$ 15,401
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues	(80)	(149)
Cost of sales	(80)	(149)
Operating income (loss)	(1)	1
Income (loss) from equity investees	0	0
Other non-operating (loss) income, net	0	0
(Loss) earnings before interest expense and income taxes	(1)	1
Interest expense	0	0
Income (loss) before income taxes	(1)	1
Depreciation and amortization	0	0
Capital expenditures (including the effects of accruals)	0	0
Total assets	(190)	(252)
Intersegment Eliminations [Member] | Utilities
Segment Reporting Information [Line Items]
Revenues	13	33
Intersegment Eliminations [Member] | Midstream & Marketing
Segment Reporting Information [Line Items]
Revenues	67	115
Intersegment Eliminations [Member] | UGI International
Segment Reporting Information [Line Items]
Revenues	0	0
Intersegment Eliminations [Member] | AmeriGas Propane
Segment Reporting Information [Line Items]
Revenues	0	0
Operating Segments | Utilities
Segment Reporting Information [Line Items]
Revenues	493	592
Revenues from external customers	480	559
Cost of sales	221	329
Operating income (loss)	134	126
Income (loss) from equity investees	0	0
Other non-operating (loss) income, net	1	2
(Loss) earnings before interest expense and income taxes	135	128
Interest expense	(23)	(21)
Income (loss) before income taxes	112	107
Depreciation and amortization	41	37
Capital expenditures (including the effects of accruals)	82	117
Total assets	5,855	5,680
Operating Segments | Midstream & Marketing
Segment Reporting Information [Line Items]
Revenues	394	669
Revenues from external customers	327	554
Cost of sales	239	514
Operating income (loss)	99	106
Income (loss) from equity investees	3	1
Other non-operating (loss) income, net	0	0
(Loss) earnings before interest expense and income taxes	102	107
Interest expense	(11)	(11)
Income (loss) before income taxes	91	96
Depreciation and amortization	22	21
Capital expenditures (including the effects of accruals)	19	11
Total assets	3,236	3,298
Operating Segments | UGI International
Segment Reporting Information [Line Items]
Revenues	725	877
Cost of sales	446	662
Operating income (loss)	113	56
Income (loss) from equity investees	(2)	0
Other non-operating (loss) income, net	6	10
(Loss) earnings before interest expense and income taxes	117	66
Interest expense	(11)	(7)
Income (loss) before income taxes	106	59
Depreciation and amortization	30	28
Capital expenditures (including the effects of accruals)	12	27
Total assets	3,150	3,889
Operating Segments | AmeriGas Propane
Segment Reporting Information [Line Items]
Revenues	629	766
Cost of sales	283	386
Operating income (loss)	71	110
Income (loss) from equity investees	0	0
Other non-operating (loss) income, net	0	0
(Loss) earnings before interest expense and income taxes	71	110
Interest expense	(41)	(43)
Income (loss) before income taxes	30	67
Depreciation and amortization	44	44
Capital expenditures (including the effects of accruals)	20	23
Total assets	3,460	4,331
Corporate & Other
Segment Reporting Information [Line Items]
Revenues from external customers	(40)	3
Cost of sales	93	1,364
Operating income (loss)	(184)	(1,603)
Income (loss) from equity investees	0	0
Other non-operating (loss) income, net	(20)	(40)
(Loss) earnings before interest expense and income taxes	(204)	(1,643)
Interest expense	(14)	(10)
Income (loss) before income taxes	(218)	(1,653)
Depreciation and amortization	0	1
Capital expenditures (including the effects of accruals)	0	0
Total assets	205	182
Intersegment revenues Corporate & Other
Segment Reporting Information [Line Items]
Revenues	$ 0	$ 1