Segment Information - Schedule of Segment Reporting (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information [Line Items]
Revenues	$ 1,124	$ 1,199	$ 2,229	$ 2,007	$ 1,150	$ 1,364	$ 2,606	$ 2,200	$ 6,559	$ 7,320	$ 7,651
Cost of sales									3,149	4,323	4,075
Operating income (loss)	69	174	362	377	(99)	9	539	168	982	617	1,065
Income (loss) from equity investees									27	9	4
Loss on extinguishments of debt				(4)					0	(6)
Other non-operating (expense) income, net									(20)	39	16
Earnings (losses) before interest expense and income taxes									989	659	1,085
Interest expense									(322)	(258)	(230)
Income tax (expense) benefit									(135)	(93)	(33)
Noncontrolling interests’ net (income) loss									0	(52)	(103)
Net income attributable to UGI Corporation	9	$ 85	$ 226	$ 212	(52)	$ (2)	$ 246	$ 64	532	256	719
Depreciation and amortization									484	448	455
Total assets	13,985				13,347				13,985	13,347	11,981
Short-term borrowings	347				796				347	796	425
Capital expenditures (including the effects of accruals)									665	707	597
Investments in equity investees	200				190				200	190	88
Eliminations
Segment Reporting Information [Line Items]
Revenues									(232)	(306)	(371)
Cost of sales									(229)	(301)	(367)
Operating income (loss)									0	0	1
Income (loss) from equity investees									0	0	0
Loss on extinguishments of debt										0
Other non-operating (expense) income, net									0	(1)	(1)
Earnings (losses) before interest expense and income taxes									0	(1)	0
Interest expense									0	0	0
Income tax (expense) benefit										0	(1)
Noncontrolling interests’ net (income) loss										0	0
Net income attributable to UGI Corporation									0	(1)	(1)
Depreciation and amortization									0	0	0
Total assets	(282)				(353)				(282)	(353)	(125)
Short-term borrowings	0				0				0	0	0
Capital expenditures (including the effects of accruals)									0	0	0
Investments in equity investees	0				0				0	0	0
Eliminations | AmeriGas Propane
Segment Reporting Information [Line Items]
Revenues									0	0	0
Eliminations | UGI International
Segment Reporting Information [Line Items]
Revenues									0	0	0
Eliminations | Midstream & Marketing
Segment Reporting Information [Line Items]
Revenues									182	235	273
Eliminations | UGI Utilities
Segment Reporting Information [Line Items]
Revenues									47	68	94
Operating Segments | AmeriGas Propane
Segment Reporting Information [Line Items]
Revenues									2,381	2,682	2,823
Cost of sales									960	1,191	1,315
Operating income (loss)									373	404	422
Income (loss) from equity investees									0	0	0
Loss on extinguishments of debt										0
Other non-operating (expense) income, net									0	0	0
Earnings (losses) before interest expense and income taxes									373	404	422
Interest expense									(164)	(167)	(163)
Income tax (expense) benefit									(53)	(26)	(31)
Noncontrolling interests’ net (income) loss										(143)	(152)
Net income attributable to UGI Corporation									156	68	76
Depreciation and amortization									178	179	186
Total assets	4,327				4,095				4,327	4,095	3,934
Short-term borrowings	186				328				186	328	232
Capital expenditures (including the effects of accruals)									135	107	101
Investments in equity investees	0				0				0	0	0
Operating Segments | UGI International
Segment Reporting Information [Line Items]
Revenues									2,127	2,372	2,684
Cost of sales									1,191	1,416	1,620
Operating income (loss)									241	229	248
Income (loss) from equity investees									0	0	(1)
Loss on extinguishments of debt										0
Other non-operating (expense) income, net									18	5	(7)
Earnings (losses) before interest expense and income taxes									259	234	240
Interest expense									(31)	(25)	(21)
Income tax (expense) benefit									(55)	(64)	(69)
Noncontrolling interests’ net (income) loss										0	3
Net income attributable to UGI Corporation									173	145	153
Depreciation and amortization									125	124	141
Total assets	3,123				2,975				3,123	2,975	3,279
Short-term borrowings	1				211				1	211	1
Capital expenditures (including the effects of accruals)									89	106	111
Investments in equity investees	10				12				10	12	13
Operating Segments | Midstream & Marketing
Segment Reporting Information [Line Items]
Revenues									1,247	1,516
Revenues from external customers									1,065	1,281	1,149
Cost of sales									892	1,241	1,091
Operating income (loss)									140	105	175
Income (loss) from equity investees									27	9	5
Loss on extinguishments of debt										0
Other non-operating (expense) income, net									1	0	(1)
Earnings (losses) before interest expense and income taxes									168	114	179
Interest expense									(42)	(9)	(2)
Income tax (expense) benefit									(34)	(27)	(50)
Noncontrolling interests’ net (income) loss										0	0
Net income attributable to UGI Corporation									92	78	127
Depreciation and amortization									75	51	43
Total assets	2,775				2,745				2,775	2,745	1,329
Short-term borrowings	19				91				19	91	2
Capital expenditures (including the effects of accruals)									93	138	43
Investments in equity investees	190				178				190	178	75
Operating Segments | UGI Utilities
Segment Reporting Information [Line Items]
Revenues									1,030	1,049
Revenues from external customers									983	981	998
Cost of sales									448	481	523
Operating income (loss)									229	224	240
Income (loss) from equity investees									0	0	0
Loss on extinguishments of debt										0
Other non-operating (expense) income, net									0	2	(2)
Earnings (losses) before interest expense and income taxes									229	226	238
Interest expense									(54)	(50)	(43)
Income tax (expense) benefit									(39)	(43)	(54)
Noncontrolling interests’ net (income) loss										0	0
Net income attributable to UGI Corporation									136	133	141
Depreciation and amortization									105	93	85
Total assets	3,809				3,560				3,809	3,560	3,266
Short-term borrowings	141				166				141	166	190
Capital expenditures (including the effects of accruals)									348	355	339
Investments in equity investees	0				0				0	0	0
Corporate & Other
Segment Reporting Information [Line Items]
Revenues									6	7
Revenues from external customers									3	4	(3)
Cost of sales									(113)	295	(107)
Operating income (loss)									(1)	(345)	(21)
Income (loss) from equity investees									0	0	0
Loss on extinguishments of debt										(6)
Other non-operating (expense) income, net									(39)	33	27
Earnings (losses) before interest expense and income taxes									(40)	(318)	6
Interest expense									(31)	(7)	(1)
Income tax (expense) benefit									46	67	172
Noncontrolling interests’ net (income) loss										91	46
Net income attributable to UGI Corporation									(25)	(167)	223
Depreciation and amortization									1	1	0
Total assets	233				325				233	325	298
Short-term borrowings	0				0				0	0	0
Capital expenditures (including the effects of accruals)									0	1	3
Investments in equity investees	$ 0				$ 0				0	0	0
Corporate & Other | AmeriGas Propane
Segment Reporting Information [Line Items]
Loss on extinguishments of debt										0
Corporate & Other | UGI International
Segment Reporting Information [Line Items]
Loss on extinguishments of debt										(6)
Corporate & Other | Midstream & Marketing
Segment Reporting Information [Line Items]
Loss on extinguishments of debt										0
Corporate, Intersegment Eliminations & Other
Segment Reporting Information [Line Items]
Revenues									$ 3	$ 3	$ 4