Segment Information - Schedule of Segment Reporting Information (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Sep. 30, 2018
Segment Reporting Information [Line Items]
Revenues	$ 2,200.2	$ 2,125.2
Cost of sales	1,425.0	1,137.4
Segment profit:
Operating income (loss)	167.7	395.0
Income from equity investees	1.5	1.0
Loss on extinguishments of debt	(6.1)	0.0
Other non-operating income (expense), net	9.0	(8.0)
Interest expense	(60.2)	(58.2)
(Loss) income before income taxes	111.9	329.8
Noncontrolling interests’ net loss	24.3	68.3
Depreciation and amortization	111.2	110.3
Capital expenditures (including the effects of accruals)	161.8	128.5
Total assets	12,368.3	12,343.9	$ 11,980.9
Short-term borrowings	676.3	586.1	424.9
Goodwill	3,154.8	3,185.5	$ 3,160.4
Eliminations
Segment Reporting Information [Line Items]
Revenues	(111.6)	(97.1)
Cost of sales	(110.8)	(96.0)
Segment profit:
Operating income (loss)	0.4	0.2
Income from equity investees	0.0	0.0
Loss on extinguishments of debt	0.0
Other non-operating income (expense), net	0.0	0.0
Interest expense	0.0	0.0
(Loss) income before income taxes	0.4	0.2
Noncontrolling interests’ net loss	0.0	0.0
Depreciation and amortization	0.0	0.0
Capital expenditures (including the effects of accruals)	0.0	0.0
Total assets	(144.3)	(62.6)
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	86.9	78.2
Eliminations | UGI Utilities
Segment Reporting Information [Line Items]
Revenues	23.6	17.7
Corporate, Intersegment Eliminations & Other
Segment Reporting Information [Line Items]
Revenues	1.1	1.2
Operating Segments | AmeriGas Propane
Segment Reporting Information [Line Items]
Revenues	820.2	787.3
Cost of sales	378.5	366.1
Segment profit:
Operating income (loss)	166.6	147.9
Income from equity investees	0.0	0.0
Loss on extinguishments of debt	0.0
Other non-operating income (expense), net	0.0	0.0
Interest expense	(42.4)	(40.6)
(Loss) income before income taxes	124.2	107.3
Partnership Adjusted EBITDA	210.7	194.1
Noncontrolling interests’ net loss	81.5	68.0
Depreciation and amortization	45.7	47.4
Capital expenditures (including the effects of accruals)	31.0	23.6
Total assets	4,020.6	4,206.2
Short-term borrowings	368.5	263.5
Goodwill	2,003.0	2,001.3
Operating Segments | UGI International
Segment Reporting Information [Line Items]
Revenues	710.7	784.2
Cost of sales	448.6	484.8
Segment profit:
Operating income (loss)	58.3	93.2
Income from equity investees	0.0	(0.2)
Loss on extinguishments of debt	(6.1)
Other non-operating income (expense), net	0.7	(4.8)
Interest expense	(5.4)	(5.6)
(Loss) income before income taxes	47.5	82.6
Noncontrolling interests’ net loss	0.1	(0.3)
Depreciation and amortization	31.4	32.2
Capital expenditures (including the effects of accruals)	27.8	21.7
Total assets	3,287.5	3,450.1
Short-term borrowings	1.8	41.1
Goodwill	951.9	990.6
Operating Segments | Midstream & Marketing
Segment Reporting Information [Line Items]
Revenues	459.4	249.8
Revenues, before intersegment effect	372.5
Cost of sales	377.5	239.0
Segment profit:
Operating income (loss)	41.1	53.4
Income from equity investees	1.5	1.2
Loss on extinguishments of debt	0.0
Other non-operating income (expense), net	0.0	(1.1)
Interest expense	(0.5)	(0.9)
(Loss) income before income taxes	42.1	52.6
Noncontrolling interests’ net loss	0.0	0.0
Depreciation and amortization	11.5	10.1
Capital expenditures (including the effects of accruals)	25.1	11.3
Total assets	1,504.9	1,325.1
Short-term borrowings	10.0	100.0
Goodwill	17.8	11.5
Operating Segments | UGI Utilities
Segment Reporting Information [Line Items]
Revenues	322.7	305.4
Revenues, before intersegment effect	299.1
Cost of sales	159.5	151.8
Segment profit:
Operating income (loss)	77.0	96.9
Income from equity investees	0.0	0.0
Loss on extinguishments of debt	0.0
Other non-operating income (expense), net	0.4	(0.6)
Interest expense	(11.7)	(10.9)
(Loss) income before income taxes	65.7	85.4
Noncontrolling interests’ net loss	0.0	0.0
Depreciation and amortization	22.5	20.4
Capital expenditures (including the effects of accruals)	77.3	71.7
Total assets	3,424.8	3,174.7
Short-term borrowings	296.0	181.5
Goodwill	182.1	182.1
Corporate & Other
Segment Reporting Information [Line Items]
Revenues	(1.2)	(1.5)
Revenues, before intersegment effect	(2.3)
Cost of sales	171.7	(8.3)
Segment profit:
Operating income (loss)	(175.7)	3.4
Income from equity investees	0.0	0.0
Loss on extinguishments of debt	0.0
Other non-operating income (expense), net	7.9	(1.5)
Interest expense	(0.2)	(0.2)
(Loss) income before income taxes	(168.0)	1.7
Noncontrolling interests’ net loss	(57.3)	0.6
Depreciation and amortization	0.1	0.2
Capital expenditures (including the effects of accruals)	0.6	0.2
Total assets	274.8	250.4
Short-term borrowings	0.0	0.0
Goodwill	$ 0.0	$ 0.0