Segment Information - Schedule of Segment Reporting Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Sep. 30, 2018
Segment Reporting Information [Line Items]
Revenues	$ 1,363.7	$ 1,440.9	$ 6,170.0	$ 6,378.1
Cost of sales	781.4	732.5	3,633.3	3,430.1
Segment profit:
Operating income (loss)	9.6	29.5	716.1	1,015.5
Income from equity investees	1.5	1.3	4.6	3.0
Loss on extinguishments of debt	0.0	0.0	(6.1)	0.0
Other non-operating income (expense), net	0.7	24.6	17.6	4.1
Interest expense	(60.5)	(56.5)	(181.7)	(172.8)
(Loss) income before income taxes	(48.7)	(1.1)	550.5	849.8
Noncontrolling interests’ net income (loss)	(44.6)	(64.1)	131.0	135.9
Depreciation and amortization	109.9	118.8	330.0	341.3
Capital expenditures (including the effects of accruals)	166.0	142.7	479.0	381.3
Total assets	12,018.9	11,876.7	12,018.9	11,876.7	$ 11,980.9
Short-term borrowings	380.2	299.1	380.2	299.1	424.9
Goodwill	3,159.1	3,169.0	3,159.1	3,169.0	$ 3,160.4
Eliminations
Segment Reporting Information [Line Items]
Revenues	(39.6)	(44.4)	(276.0)	(330.4)
Cost of sales	(38.5)	(43.5)	(272.9)	(327.4)
Segment profit:
Operating income (loss)	0.2	(0.3)	0.2	0.2
Income from equity investees	0.0	0.0	0.0	0.0
Loss on extinguishments of debt			0.0
Other non-operating income (expense), net	0.0	0.0	0.0	0.0
Interest expense	0.0	0.0	0.0	0.0
(Loss) income before income taxes	0.2	(0.3)	0.2	0.2
Noncontrolling interests’ net income (loss)	0.0	0.0	0.0	0.0
Depreciation and amortization	(0.2)	(0.1)	(0.3)	(0.2)
Capital expenditures (including the effects of accruals)	0.0	0.0	0.0	0.0
Total assets	(116.9)	(74.2)	(116.9)	(74.2)
Short-term borrowings	0.0	0.0	0.0	0.0
Goodwill	0.0	0.0	0.0	0.0
Eliminations | AmeriGas Propane
Segment Reporting Information [Line Items]
Revenues	0.0	0.0	0.0	0.0
Eliminations | UGI International
Segment Reporting Information [Line Items]
Revenues	0.0	0.0	0.0	0.0
Eliminations | Midstream & Marketing
Segment Reporting Information [Line Items]
Revenues	28.0	34.2	213.7	241.4
Eliminations | UGI Utilities
Segment Reporting Information [Line Items]
Revenues	10.9	9.6	59.8	86.0
Corporate, Intersegment Eliminations & Other
Segment Reporting Information [Line Items]
Revenues	0.7	0.6	2.5	3.0
Operating Segments | AmeriGas Propane
Segment Reporting Information [Line Items]
Revenues	478.7	528.4	2,270.5	2,356.0
Cost of sales	210.3	244.5	1,024.0	1,094.3
Segment profit:
Operating income (loss)	(3.0)	(54.7)	410.0	359.8
Income from equity investees	0.0	0.0	0.0	0.0
Loss on extinguishments of debt			0.0
Other non-operating income (expense), net	0.0	0.0	0.0	0.0
Interest expense	(41.6)	(40.4)	(126.2)	(122.0)
(Loss) income before income taxes	(44.6)	(95.1)	283.8	237.8
Partnership Adjusted EBITDA	42.5	67.2	543.5	570.8
Noncontrolling interests’ net income (loss)	(42.1)	(78.1)	178.1	145.6
Depreciation and amortization	44.0	46.4	134.0	139.0
Capital expenditures (including the effects of accruals)	21.0	25.7	77.8	72.9
Total assets	3,789.4	3,932.7	3,789.4	3,932.7
Short-term borrowings	248.5	177.0	248.5	177.0
Goodwill	2,003.0	2,005.5	2,003.0	2,005.5
Operating Segments | UGI International
Segment Reporting Information [Line Items]
Revenues	486.6	533.6	1,980.5	2,227.4
Cost of sales	278.5	314.3	1,171.8	1,340.2
Segment profit:
Operating income (loss)	27.5	9.2	212.7	234.4
Income from equity investees	0.0	0.0	0.1	(0.3)
Loss on extinguishments of debt			(6.1)
Other non-operating income (expense), net	1.2	(0.7)	5.0	(14.7)
Interest expense	(5.8)	(5.5)	(17.3)	(16.3)
(Loss) income before income taxes	22.9	3.0	194.4	203.1
Noncontrolling interests’ net income (loss)	(0.1)	(0.8)	0.2	(2.3)
Depreciation and amortization	30.8	39.8	92.8	106.9
Capital expenditures (including the effects of accruals)	24.1	27.3	74.0	75.1
Total assets	3,168.0	3,232.5	3,168.0	3,232.5
Short-term borrowings	0.7	3.6	0.7	3.6
Goodwill	956.2	969.9	956.2	969.9
Operating Segments | Midstream & Marketing
Segment Reporting Information [Line Items]
Revenues	267.3		1,269.1
Revenues	239.3	229.6	1,055.4	915.6
Cost of sales	225.4	215.0	1,052.2	872.6
Segment profit:
Operating income (loss)	2.7	7.4	95.1	168.4
Income from equity investees	1.5	1.3	4.5	3.3
Loss on extinguishments of debt			0.0
Other non-operating income (expense), net	0.1	0.0	0.1	(1.2)
Interest expense	(0.7)	(0.5)	(1.7)	(2.1)
(Loss) income before income taxes	3.6	8.2	98.0	168.4
Noncontrolling interests’ net income (loss)	0.0	0.0	0.0	0.0
Depreciation and amortization	11.8	11.1	34.8	32.0
Capital expenditures (including the effects of accruals)	36.4	9.9	93.8	25.5
Total assets	1,444.7	1,316.5	1,444.7	1,316.5
Short-term borrowings	55.0	0.0	55.0	0.0
Goodwill	17.8	11.5	17.8	11.5
Operating Segments | UGI Utilities
Segment Reporting Information [Line Items]
Revenues	163.9		916.2
Revenues	153.0	150.3	856.4	880.3
Cost of sales	61.0	72.5	438.5	481.6
Segment profit:
Operating income (loss)	20.4	4.4	217.3	237.0
Income from equity investees	0.0	0.0	0.0	0.0
Loss on extinguishments of debt			0.0
Other non-operating income (expense), net	0.4	(0.5)	1.2	(1.7)
Interest expense	(12.4)	(10.0)	(36.3)	(32.0)
(Loss) income before income taxes	8.4	(6.1)	182.2	203.3
Noncontrolling interests’ net income (loss)	0.0	0.0	0.0	0.0
Depreciation and amortization	23.2	21.4	68.0	62.9
Capital expenditures (including the effects of accruals)	84.5	79.7	232.6	206.5
Total assets	3,375.6	3,194.0	3,375.6	3,194.0
Short-term borrowings	76.0	118.5	76.0	118.5
Goodwill	182.1	182.1	182.1	182.1
Corporate & Other
Segment Reporting Information [Line Items]
Revenues	6.8		9.7
Revenues	6.1	(1.0)	7.2	(1.2)
Cost of sales	44.7	(70.3)	219.7	(31.2)
Segment profit:
Operating income (loss)	(38.2)	63.5	(219.2)	15.7
Income from equity investees	0.0	0.0	0.0	0.0
Loss on extinguishments of debt			0.0
Other non-operating income (expense), net	(1.0)	25.8	11.3	21.7
Interest expense	0.0	(0.1)	(0.2)	(0.4)
(Loss) income before income taxes	(39.2)	89.2	(208.1)	37.0
Noncontrolling interests’ net income (loss)	(2.4)	14.8	(47.3)	(7.4)
Depreciation and amortization	0.3	0.2	0.7	0.7
Capital expenditures (including the effects of accruals)	0.0	0.1	0.8	1.3
Total assets	358.1	275.2	358.1	275.2
Short-term borrowings	0.0	0.0	0.0	0.0
Goodwill	$ 0.0	$ 0.0	$ 0.0	$ 0.0