Segment Information - Schedule of Segment Reporting Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Sep. 30, 2020
Segment Reporting Information [Line Items]
Revenues	$ 1,496	$ 1,199	$ 6,009	$ 5,435
Cost of sales	516	417	2,623	2,673
Operating income (loss)	391	174	1,564	913
(Loss) income from equity investees	(86)	7	(69)	22
Other non-operating income (expense), net	1	(4)	0	(4)
Earnings (loss) before interest expense and income taxes	306	177	1,495	931
Interest expense	(77)	(80)	(233)	(247)
Income (loss) before income taxes	229	97	1,262	684
Depreciation and amortization	125	122	375	362
Capital expenditures (including the effects of accruals)	162	133	438	444
Total assets	15,006	13,843	15,006	13,843	$ 13,985
Eliminations
Segment Reporting Information [Line Items]
Revenues	(40)	(28)	(236)	(202)
Cost of sales	(39)	(28)	(233)	(201)
Operating income (loss)	0	0	0	0
(Loss) income from equity investees	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
Income (loss) 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	(267)	(365)	(267)	(365)
Eliminations | AmeriGas Propane
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Eliminations | UGI International
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Eliminations | Midstream & Marketing
Segment Reporting Information [Line Items]
Revenues	29	20	183	162
Eliminations | UGI Utilities
Segment Reporting Information [Line Items]
Revenues	10	7	50	38
Operating Segments | AmeriGas Propane
Segment Reporting Information [Line Items]
Revenues	526	451	2,132	1,983
Cost of sales	267	178	970	792
Operating income (loss)	11	19	391	390
(Loss) income from equity investees	0	0	0	0
Other non-operating income (expense), net	0	0	0	0
Earnings (loss) before interest expense and income taxes	11	19	391	390
Interest expense	(40)	(41)	(120)	(124)
Income (loss) before income taxes	(29)	(22)	271	266
Depreciation and amortization	43	45	130	134
Capital expenditures (including the effects of accruals)	26	30	83	104
Total assets	4,381	4,311	4,381	4,311
Operating Segments | UGI International
Segment Reporting Information [Line Items]
Revenues	572	371	2,106	1,726
Cost of sales	355	198	1,229	968
Operating income (loss)	40	17	322	230
(Loss) income from equity investees	0	0	0	0
Other non-operating income (expense), net	1	4	4	17
Earnings (loss) before interest expense and income taxes	41	21	326	247
Interest expense	(8)	(8)	(21)	(23)
Income (loss) before income taxes	33	13	305	224
Depreciation and amortization	33	30	100	92
Capital expenditures (including the effects of accruals)	21	20	68	62
Total assets	3,749	3,208	3,749	3,208
Operating Segments | Midstream & Marketing
Segment Reporting Information [Line Items]
Revenues	261	222	1,086	1,017
Revenues, before intersegment effect	232	202	903	855
Cost of sales	196	158	776	721
Operating income (loss)	14	13	156	139
(Loss) income from equity investees	7	7	24	22
Other non-operating income (expense), net	0	0	0	0
Earnings (loss) before interest expense and income taxes	21	20	180	161
Interest expense	(10)	(11)	(31)	(34)
Income (loss) before income taxes	11	9	149	127
Depreciation and amortization	19	20	56	57
Capital expenditures (including the effects of accruals)	3	15	32	61
Total assets	2,904	2,740	2,904	2,740
Operating Segments | UGI Utilities
Segment Reporting Information [Line Items]
Revenues	181	179	923	901
Revenues, before intersegment effect	171	172	873	863
Cost of sales	67	68	401	404
Operating income (loss)	24	21	243	229
(Loss) income from equity investees	0	0	0	0
Other non-operating income (expense), net	1	0	2	0
Earnings (loss) before interest expense and income taxes	25	21	245	229
Interest expense	(14)	(14)	(42)	(41)
Income (loss) before income taxes	11	7	203	188
Depreciation and amortization	29	26	87	78
Capital expenditures (including the effects of accruals)	112	68	255	217
Total assets	3,997	3,709	3,997	3,709
Corporate & Other
Segment Reporting Information [Line Items]
Revenues, before intersegment effect	(5)	3	(5)	8
Cost of sales	(330)	(157)	(520)	(11)
Operating income (loss)	302	104	452	(75)
(Loss) income from equity investees	(93)	0	(93)	0
Other non-operating income (expense), net	(1)	(8)	(6)	(21)
Earnings (loss) before interest expense and income taxes	208	96	353	(96)
Interest expense	(5)	(6)	(19)	(25)
Income (loss) before income taxes	203	90	334	(121)
Depreciation and amortization	1	1	2	1
Capital expenditures (including the effects of accruals)	0	0	0	0
Total assets	242	240	242	240
Intersegment revenues Corporate & Other
Segment Reporting Information [Line Items]
Revenues	$ 1	$ 1	$ 3	$ 2