Segment Information - Schedule of Segment Reporting Information (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Sep. 30, 2021
Segment Reporting Information [Line Items]
Revenues from external customers	$ 2,673	$ 1,932
Cost of sales	2,120	833
Operating (loss) income	(68)	502
Income from equity investees	8	7
Loss on extinguishment of debt	(11)	0
Other non-operating (expense) income, net	10	(19)
(Loss) earnings before interest expense and income taxes	(61)	490
Interest expense	(81)	(78)
(Loss) income before income taxes	(142)	412
Depreciation and amortization	129	124
Capital expenditures (including the effects of accruals)	175	152
Total assets	16,800	14,725	$ 16,723
AmeriGas Propane
Segment Reporting Information [Line Items]
Loss on extinguishment of debt	0
UGI International
Segment Reporting Information [Line Items]
Loss on extinguishment of debt	(11)
Midstream & Marketing
Segment Reporting Information [Line Items]
Loss on extinguishment of debt	0
Eliminations
Segment Reporting Information [Line Items]
Revenues from external customers	(118)	(78)
Cost of sales	(117)	(77)
Operating (loss) income	0	0
Income from equity investees	0	0
Loss on extinguishment of debt	0
Other non-operating (expense) income, net	0	0
(Loss) earnings before interest expense and income taxes	0	0
Interest expense	0	0
(Loss) income before income taxes	0	0
Depreciation and amortization	0	0
Capital expenditures (including the effects of accruals)	0	0
Total assets	(269)	(353)
Eliminations | AmeriGas Propane
Segment Reporting Information [Line Items]
Revenues from external customers	0	0
Eliminations | UGI International
Segment Reporting Information [Line Items]
Revenues from external customers	0	0
Eliminations | Midstream & Marketing
Segment Reporting Information [Line Items]
Revenues from external customers	94	62
Eliminations | Utilities
Segment Reporting Information [Line Items]
Revenues from external customers	23	15
Operating Segments | AmeriGas Propane
Segment Reporting Information [Line Items]
Revenues from external customers	778	666
Cost of sales	418	272
Operating (loss) income	86	141
Income from equity investees	0	0
Loss on extinguishment of debt	0
Other non-operating (expense) income, net	0	0
(Loss) earnings before interest expense and income taxes	86	141
Interest expense	(41)	(40)
(Loss) income before income taxes	45	101
Depreciation and amortization	44	43
Capital expenditures (including the effects of accruals)	35	27
Total assets	4,614	4,471
Operating Segments | UGI International
Segment Reporting Information [Line Items]
Revenues from external customers	1,049	700
Cost of sales	793	383
Operating (loss) income	78	135
Income from equity investees	0	0
Loss on extinguishment of debt	0
Other non-operating (expense) income, net	4	1
(Loss) earnings before interest expense and income taxes	82	136
Interest expense	(7)	(7)
(Loss) income before income taxes	75	129
Depreciation and amortization	31	33
Capital expenditures (including the effects of accruals)	23	29
Total assets	4,197	3,564
Operating Segments | Midstream & Marketing
Segment Reporting Information [Line Items]
Revenues from external customers	535	341
Revenues, before intersegment effect	441	279
Cost of sales	413	237
Operating (loss) income	74	52
Income from equity investees	8	7
Loss on extinguishment of debt	0
Other non-operating (expense) income, net	0	0
(Loss) earnings before interest expense and income taxes	82	59
Interest expense	(10)	(10)
(Loss) income before income taxes	72	49
Depreciation and amortization	19	18
Capital expenditures (including the effects of accruals)	6	17
Total assets	2,999	2,851
Operating Segments | Utilities
Segment Reporting Information [Line Items]
Revenues from external customers	419	300
Revenues, before intersegment effect	396	285
Cost of sales	200	132
Operating (loss) income	96	77
Income from equity investees	0	0
Loss on extinguishment of debt	0
Other non-operating (expense) income, net	2	1
(Loss) earnings before interest expense and income taxes	98	78
Interest expense	(16)	(14)
(Loss) income before income taxes	82	64
Depreciation and amortization	35	29
Capital expenditures (including the effects of accruals)	111	79
Total assets	5,071	3,959
Corporate & Other
Segment Reporting Information [Line Items]
Revenues, before intersegment effect	9	2
Cost of sales	413	(114)
Operating (loss) income	(402)	97
Income from equity investees	0	0
Loss on extinguishment of debt	(11)
Other non-operating (expense) income, net	4	(21)
(Loss) earnings before interest expense and income taxes	(409)	76
Interest expense	(7)	(7)
(Loss) income before income taxes	(416)	69
Depreciation and amortization	0	1
Capital expenditures (including the effects of accruals)	0	0
Total assets	188	233
Intersegment revenues Corporate & Other
Segment Reporting Information [Line Items]
Revenues from external customers	$ 1	$ 1