Segment Information - Schedule of Segment Reporting Information (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Sep. 30, 2019
Segment Reporting Information [Line Items]
Revenues	$ 2,006.6	$ 2,200.2
Cost of sales	1,008.0	1,425.0
Operating income (loss)	377.2	167.7
Income from equity investees	6.5	1.5
Loss on extinguishments of debt	0.0	(6.1)
Other non-operating (expense) income, net	(11.5)	9.0
Earnings (loss) before interest expense and income taxes	372.2	172.1
Interest expense	(84.1)	(60.2)
Income before income taxes	288.1	111.9
Noncontrolling interests’ net income (loss)	0.0	24.3
Depreciation and amortization	119.4	111.2
Capital expenditures (including the effects of accruals)	151.8	161.8
Total assets	14,285.7	12,368.3	$ 13,346.6
Short-term borrowings	869.7	676.3	796.3
Goodwill	3,482.9	3,154.8	$ 3,456.4
Eliminations
Segment Reporting Information [Line Items]
Revenues	(79.7)	(111.6)
Cost of sales	(79.1)	(110.8)
Operating income (loss)	0.3	0.4
Income from equity investees	0.0	0.0
Loss on extinguishments of debt		0.0
Other non-operating (expense) income, net	0.0	0.0
Earnings (loss) before interest expense and income taxes	0.3	0.4
Interest expense	0.0	0.0
Income before income taxes	0.3	0.4
Noncontrolling interests’ net income (loss)		0.0
Depreciation and amortization	0.0	0.0
Capital expenditures (including the effects of accruals)	0.0	0.0
Total assets	(365.5)	(144.3)
Short-term borrowings	0.0	0.0
Goodwill	0.0	0.0
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	64.2	86.9
Eliminations | UGI Utilities
Segment Reporting Information [Line Items]
Revenues	14.7	23.6
Corporate, Intersegment Eliminations & Other
Segment Reporting Information [Line Items]
Revenues	0.8	1.1
Operating Segments | AmeriGas Propane
Segment Reporting Information [Line Items]
Revenues	730.4	820.2
Cost of sales	289.2	378.5
Operating income (loss)	165.3	166.6
Income from equity investees	0.0	0.0
Loss on extinguishments of debt		0.0
Other non-operating (expense) income, net	0.0	0.0
Earnings (loss) before interest expense and income taxes	165.3	166.6
Interest expense	(42.5)	(42.4)
Income before income taxes	122.8	124.2
Noncontrolling interests’ net income (loss)		81.5
Depreciation and amortization	43.9	45.7
Capital expenditures (including the effects of accruals)	38.5	31.0
Total assets	4,609.4	4,020.6
Short-term borrowings	321.0	368.5
Goodwill	2,003.0	2,003.0
Operating Segments | UGI International
Segment Reporting Information [Line Items]
Revenues	651.4	710.7
Cost of sales	368.4	448.6
Operating income (loss)	95.8	58.3
Income from equity investees	0.0	0.0
Loss on extinguishments of debt		0.0
Other non-operating (expense) income, net	4.4	0.7
Earnings (loss) before interest expense and income taxes	100.2	59.0
Interest expense	(7.6)	(5.4)
Income before income taxes	92.6	53.6
Noncontrolling interests’ net income (loss)		0.1
Depreciation and amortization	31.2	31.4
Capital expenditures (including the effects of accruals)	20.3	27.8
Total assets	3,243.3	3,287.5
Short-term borrowings	181.3	1.8
Goodwill	956.8	951.9
Operating Segments | Midstream & Marketing
Segment Reporting Information [Line Items]
Revenues	372.5	459.4
Revenues	308.3	372.5
Cost of sales	264.2	377.5
Operating income (loss)	55.1	41.1
Income from equity investees	6.5	1.5
Loss on extinguishments of debt		0.0
Other non-operating (expense) income, net	0.0	0.0
Earnings (loss) before interest expense and income taxes	61.6	42.6
Interest expense	(11.5)	(0.5)
Income before income taxes	50.1	42.1
Noncontrolling interests’ net income (loss)		0.0
Depreciation and amortization	18.4	11.5
Capital expenditures (including the effects of accruals)	22.5	25.1
Total assets	2,859.6	1,504.9
Short-term borrowings	88.4	10.0
Goodwill	341.0	17.8
Operating Segments | UGI Utilities
Segment Reporting Information [Line Items]
Revenues	329.3	322.7
Revenues	314.6	299.1
Cost of sales	151.6	159.5
Operating income (loss)	91.8	77.0
Income from equity investees	0.0	0.0
Loss on extinguishments of debt		0.0
Other non-operating (expense) income, net	(0.2)	0.4
Earnings (loss) before interest expense and income taxes	91.6	77.4
Interest expense	(13.6)	(11.7)
Income before income taxes	78.0	65.7
Noncontrolling interests’ net income (loss)		0.0
Depreciation and amortization	25.7	22.5
Capital expenditures (including the effects of accruals)	70.5	77.3
Total assets	3,710.9	3,424.8
Short-term borrowings	279.0	296.0
Goodwill	182.1	182.1
Corporate & Other
Segment Reporting Information [Line Items]
Revenues	1.9	(2.3)
Cost of sales	13.7	171.7
Operating income (loss)	(31.1)	(175.7)
Income from equity investees	0.0	0.0
Loss on extinguishments of debt		(6.1)
Other non-operating (expense) income, net	(15.7)	7.9
Earnings (loss) before interest expense and income taxes	(46.8)	(173.9)
Interest expense	(8.9)	(0.2)
Income before income taxes	(55.7)	(174.1)
Noncontrolling interests’ net income (loss)		(57.3)
Depreciation and amortization	0.2	0.1
Capital expenditures (including the effects of accruals)	0.0	0.6
Total assets	228.0	274.8
Short-term borrowings	0.0	0.0
Goodwill	$ 0.0	0.0
Corporate & Other | AmeriGas Propane
Segment Reporting Information [Line Items]
Loss on extinguishments of debt		0.0
Corporate & Other | UGI International
Segment Reporting Information [Line Items]
Loss on extinguishments of debt		(6.1)
Corporate & Other | Midstream & Marketing
Segment Reporting Information [Line Items]
Loss on extinguishments of debt		$ 0.0