Segment Information - Schedule of Segment Reporting Information (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Sep. 30, 2020
Segment Reporting Information [Line Items]
Revenues	$ 1,932.0	$ 2,007.0
Cost of sales	833.0	1,008.0
Operating income	502.0	377.0
Income (loss) from equity investees	7.0	7.0
Other non-operating expense, net	(19.0)	(12.0)
Earnings before interest expense and income taxes	490.0	372.0
Interest expense	(78.0)	(84.0)
Income before income taxes	412.0	288.0
Depreciation and amortization	124.0	119.0
Capital expenditures (including the effects of accruals)	152.0	153.0
Total assets	14,725.0	14,286.0	$ 13,985.0
Eliminations
Segment Reporting Information [Line Items]
Revenues	(78.0)	(80.0)
Cost of sales	(77.0)	(79.0)
Operating income	0.0	0.0
Income (loss) from equity investees	0.0	0.0
Other non-operating expense, 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	(353.0)	(366.0)
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	(62.0)	(64.0)
Eliminations | UGI Utilities
Segment Reporting Information [Line Items]
Revenues	(15.0)	(15.0)
Operating Segments | AmeriGas Propane
Segment Reporting Information [Line Items]
Revenues	666.0	730.0
Cost of sales	272.0	289.0
Operating income	141.0	165.0
Income (loss) from equity investees	0.0	0.0
Other non-operating expense, net	0.0	0.0
Earnings before interest expense and income taxes	141.0	165.0
Interest expense	(40.0)	(42.0)
Income before income taxes	101.0	123.0
Depreciation and amortization	43.0	44.0
Capital expenditures (including the effects of accruals)	27.0	39.0
Total assets	4,471.0	4,609.0
Operating Segments | UGI International
Segment Reporting Information [Line Items]
Revenues	700.0	651.0
Cost of sales	383.0	368.0
Operating income	135.0	96.0
Income (loss) from equity investees	0.0	0.0
Other non-operating expense, net	1.0	4.0
Earnings before interest expense and income taxes	136.0	100.0
Interest expense	(7.0)	(7.0)
Income before income taxes	129.0	93.0
Depreciation and amortization	33.0	31.0
Capital expenditures (including the effects of accruals)	29.0	20.0
Total assets	3,564.0	3,243.0
Operating Segments | Midstream & Marketing
Segment Reporting Information [Line Items]
Revenues	341.0	373.0
Revenues, before intersegment effect	279.0	309.0
Cost of sales	237.0	264.0
Operating income	52.0	55.0
Income (loss) from equity investees	7.0	7.0
Other non-operating expense, net	0.0	0.0
Earnings before interest expense and income taxes	59.0	62.0
Interest expense	(10.0)	(12.0)
Income before income taxes	49.0	50.0
Depreciation and amortization	18.0	18.0
Capital expenditures (including the effects of accruals)	17.0	23.0
Total assets	2,851.0	2,860.0
Operating Segments | UGI Utilities
Segment Reporting Information [Line Items]
Revenues	300.0	329.0
Revenues, before intersegment effect	285.0	314.0
Cost of sales	132.0	151.0
Operating income	77.0	92.0
Income (loss) from equity investees	0.0	0.0
Other non-operating expense, net	1.0	0.0
Earnings before interest expense and income taxes	78.0	92.0
Interest expense	(14.0)	(14.0)
Income before income taxes	64.0	78.0
Depreciation and amortization	29.0	26.0
Capital expenditures (including the effects of accruals)	79.0	71.0
Total assets	3,959.0	3,711.0
Corporate & Other
Segment Reporting Information [Line Items]
Revenues, before intersegment effect	2.0	3.0
Cost of sales	(114.0)	15.0
Operating income	97.0	(31.0)
Income (loss) from equity investees	0.0	0.0
Other non-operating expense, net	(21.0)	(16.0)
Earnings before interest expense and income taxes	76.0	(47.0)
Interest expense	(7.0)	(9.0)
Income before income taxes	69.0	(56.0)
Depreciation and amortization	1.0	0.0
Capital expenditures (including the effects of accruals)	0.0	0.0
Total assets	233.0	229.0
Intersegment revenues Corporate & Other
Segment Reporting Information [Line Items]
Revenues	$ (1.0)	$ (1.0)