Segment Information - Schedule of Segment Reporting Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2022	Mar. 31, 2021	Sep. 30, 2021
Segment Reporting Information [Line Items]
Revenues from external customers	$ 3,466	$ 2,581	$ 6,139	$ 4,513
Cost of sales	1,470	1,274	3,590	2,107
Operating income	1,332	671	1,264	1,173
Income from equity investees	5	10	13	17
Loss on extinguishment of debt	0	0	(11)	0
Other non-operating (expense) income, net	11	18	21	(1)
Earnings before interest expense and income taxes	1,348	699	1,287	1,189
Interest expense	(82)	(78)	(163)	(156)
Income before income taxes	1,266	621	1,124	1,033
Depreciation and amortization	128	126	257	250
Capital expenditures (including the effects of accruals)	170	124	345	276
Total assets	17,777	14,945	17,777	14,945	$ 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	(179)	(118)	(297)	(196)
Cost of sales	(178)	(117)	(295)	(194)
Operating income	0	0	0	0
Income from equity investees	0	0	0	0
Loss on extinguishment of debt			0
Other non-operating (expense) income, net	0	0	0	0
Earnings before interest expense and income taxes	0	0	0	0
Interest expense	0	0	0	0
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	(163)	(227)	(163)	(227)
Eliminations | AmeriGas Propane
Segment Reporting Information [Line Items]
Revenues from external customers	0	0	0	0
Eliminations | UGI International
Segment Reporting Information [Line Items]
Revenues from external customers	0	0	0	0
Eliminations | Midstream & Marketing
Segment Reporting Information [Line Items]
Revenues from external customers	138	92	232	154
Eliminations | Utilities
Segment Reporting Information [Line Items]
Revenues from external customers	40	25	63	40
Operating Segments | AmeriGas Propane
Segment Reporting Information [Line Items]
Revenues from external customers	1,048	940	1,826	1,606
Cost of sales	545	431	963	703
Operating income	227	239	313	380
Income from equity investees	0	0	0	0
Loss on extinguishment of debt			0
Other non-operating (expense) income, net	0	0	0	0
Earnings before interest expense and income taxes	227	239	313	380
Interest expense	(38)	(40)	(79)	(80)
Income before income taxes	189	199	234	300
Depreciation and amortization	44	44	88	87
Capital expenditures (including the effects of accruals)	36	30	71	57
Total assets	4,563	4,515	4,563	4,515
Operating Segments | UGI International
Segment Reporting Information [Line Items]
Revenues from external customers	1,224	834	2,273	1,534
Cost of sales	930	491	1,723	874
Operating income	111	147	189	282
Income from equity investees	0	0	0	0
Loss on extinguishment of debt			0
Other non-operating (expense) income, net	9	2	13	3
Earnings before interest expense and income taxes	120	149	202	285
Interest expense	(8)	(6)	(15)	(13)
Income before income taxes	112	143	187	272
Depreciation and amortization	29	34	60	67
Capital expenditures (including the effects of accruals)	23	18	46	47
Total assets	4,905	3,576	4,905	3,576
Operating Segments | Midstream & Marketing
Segment Reporting Information [Line Items]
Revenues from external customers	671	484	1,206	825
Revenues, before intersegment effect	533	392	974	671
Cost of sales	540	343	953	580
Operating income	85	90	159	142
Income from equity investees	5	10	13	17
Loss on extinguishment of debt			0
Other non-operating (expense) income, net	0	0	0	0
Earnings before interest expense and income taxes	90	100	172	159
Interest expense	(10)	(11)	(20)	(21)
Income before income taxes	80	89	152	138
Depreciation and amortization	18	19	37	37
Capital expenditures (including the effects of accruals)	10	12	16	29
Total assets	3,195	2,893	3,195	2,893
Operating Segments | Utilities
Segment Reporting Information [Line Items]
Revenues from external customers	707	442	1,126	742
Revenues, before intersegment effect	667	417	1,063	702
Cost of sales	380	202	580	334
Operating income	191	142	287	219
Income from equity investees	0	0	0	0
Loss on extinguishment of debt			0
Other non-operating (expense) income, net	3	0	5	1
Earnings before interest expense and income taxes	194	142	292	220
Interest expense	(16)	(14)	(32)	(28)
Income before income taxes	178	128	260	192
Depreciation and amortization	36	29	71	58
Capital expenditures (including the effects of accruals)	101	64	212	143
Total assets	5,106	3,982	5,106	3,982
Corporate & Other
Segment Reporting Information [Line Items]
Revenues, before intersegment effect	(6)	(2)	3	0
Cost of sales	(747)	(76)	(334)	(190)
Operating income	718	53	316	150
Income from equity investees	0	0	0	0
Loss on extinguishment of debt			(11)
Other non-operating (expense) income, net	(1)	16	3	(5)
Earnings before interest expense and income taxes	717	69	308	145
Interest expense	(10)	(7)	(17)	(14)
Income before income taxes	707	62	291	131
Depreciation and amortization	1	0	1	1
Capital expenditures (including the effects of accruals)	0	0	0	0
Total assets	171	206	171	206
Intersegment revenues Corporate & Other
Segment Reporting Information [Line Items]
Revenues from external customers	$ 1	$ 1	$ 2	$ 2