Segment Information - Schedule of Segment Reporting Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Sep. 30, 2017
Segment Reporting Information [Line Items]
Revenues	$ 1,440.9	$ 1,153.5	$ 6,378.1	$ 5,006.8
Cost of sales	732.5	618.5	3,430.1	2,337.1
Segment profit:
Operating income (loss)	28.5	(2.8)	1,009.8	976.6
Income (loss) from equity investees	1.3	0.9	3.0	3.0
Gain (loss) on foreign currency contracts, net	25.6	(16.2)	9.8	(16.1)
Loss on extinguishments of debt	0.0	(4.4)	0.0	(59.7)
Interest expense	(56.5)	(56.8)	(172.8)	(168.0)
(Loss) income before income taxes	(1.1)	(79.3)	849.8	735.8
Noncontrolling interests’ net loss	(64.1)	(43.2)	135.9	108.9
Depreciation and amortization	118.8	104.1	341.3	301.5
Capital expenditures (including the effects of accruals)	142.7	140.9	381.3	440.7
Total assets	11,876.7	11,246.4	11,876.7	11,246.4	$ 11,582.2
Short-term borrowings	299.1	163.9	299.1	163.9	366.9
Goodwill	3,169.0	3,032.3	3,169.0	3,032.3	$ 3,107.2
Eliminations
Segment Reporting Information [Line Items]
Revenues	(44.4)	(36.9)	(330.4)	(201.2)
Cost of sales	(43.5)	(36.2)	(327.4)	(198.8)
Segment profit:
Operating income (loss)	(0.3)	0.1	0.2	0.2
Income (loss) from equity investees	0.0	0.0	0.0	0.0
Gain (loss) on foreign currency contracts, net	0.0	0.0	0.0	0.0
Loss on extinguishments of debt		0.0		0.0
Interest expense	0.0	0.0	0.0	0.0
(Loss) income before income taxes	(0.3)	0.1	0.2	0.2
Noncontrolling interests’ net loss	0.0	0.0	0.0	0.0
Depreciation and amortization	(0.1)	(0.1)	(0.2)	(0.2)
Capital expenditures (including the effects of accruals)	0.0	0.0	0.0	0.0
Total assets	(74.2)	(53.0)	(74.2)	(53.0)
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	34.2	27.4	241.4	163.8
Eliminations | UGI Utilities
Segment Reporting Information [Line Items]
Revenues	9.6	8.6	86.0	34.9
Corporate, Intersegment Eliminations & Other
Segment Reporting Information [Line Items]
Revenues	0.6	0.9	3.0	2.5
Operating Segments | AmeriGas Propane
Segment Reporting Information [Line Items]
Revenues	528.4	467.5	2,356.0	2,008.3
Cost of sales	244.5	197.5	1,094.3	814.0
Segment profit:
Operating income (loss)	(54.7)	4.6	359.8	373.8
Income (loss) from equity investees	0.0	0.0	0.0	0.0
Gain (loss) on foreign currency contracts, net	0.0	0.0	0.0	0.0
Loss on extinguishments of debt	0.0	(4.4)	0.0	(59.7)
Interest expense	(40.4)	(40.6)	(122.0)	(120.6)
(Loss) income before income taxes	(95.1)	(40.4)	237.8	193.5
Partnership Adjusted EBITDA	67.2	58.4	570.8	514.7
Noncontrolling interests’ net loss	(78.1)	(38.5)	145.6	115.4
Depreciation and amortization	46.4	46.2	139.0	135.8
Capital expenditures (including the effects of accruals)	25.7	20.9	72.9	74.5
Total assets	3,932.7	4,045.7	3,932.7	4,045.7
Short-term borrowings	177.0	75.5	177.0	75.5
Goodwill	2,005.5	2,001.4	2,005.5	2,001.4
Operating Segments | UGI International
Segment Reporting Information [Line Items]
Revenues	533.6	351.3	2,227.4	1,511.1
Cost of sales	314.3	178.2	1,340.2	749.3
Segment profit:
Operating income (loss)	9.0	0.5	233.9	210.4
Income (loss) from equity investees	0.0	0.1	(0.3)	(0.2)
Gain (loss) on foreign currency contracts, net	(0.5)	(0.2)	(14.2)	0.0
Loss on extinguishments of debt		0.0		0.0
Interest expense	(5.5)	(5.6)	(16.3)	(15.2)
(Loss) income before income taxes	3.0	(5.2)	203.1	195.0
Noncontrolling interests’ net loss	(0.8)	(0.3)	(2.3)	0.0
Depreciation and amortization	39.8	31.1	106.9	86.6
Capital expenditures (including the effects of accruals)	27.3	19.1	75.1	62.1
Total assets	3,232.5	2,887.7	3,232.5	2,887.7
Short-term borrowings	3.6	8.4	3.6	8.4
Goodwill	969.9	837.3	969.9	837.3
Operating Segments | Midstream & Marketing
Segment Reporting Information [Line Items]
Revenues	229.6	195.4	915.6	752.5
Cost of sales	215.0	189.4	872.6	691.0
Segment profit:
Operating income (loss)	7.4	2.8	167.2	134.6
Income (loss) from equity investees	1.3	0.8	3.3	3.2
Gain (loss) on foreign currency contracts, net	0.0	0.0	0.0	0.0
Loss on extinguishments of debt		0.0		0.0
Interest expense	(0.5)	(0.3)	(2.1)	(1.6)
(Loss) income before income taxes	8.2	3.3	168.4	136.2
Noncontrolling interests’ net loss	0.0	0.0	0.0	0.0
Depreciation and amortization	11.1	8.8	32.0	25.6
Capital expenditures (including the effects of accruals)	9.9	21.7	25.5	104.0
Total assets	1,316.5	1,171.5	1,316.5	1,171.5
Short-term borrowings	0.0	30.0	0.0	30.0
Goodwill	11.5	11.5	11.5	11.5
Operating Segments | UGI Utilities
Segment Reporting Information [Line Items]
Revenues	150.3	138.0	880.3	733.1
Cost of sales	72.5	52.0	481.6	326.0
Segment profit:
Operating income (loss)	3.9	27.7	235.3	226.3
Income (loss) from equity investees	0.0	0.0	0.0	0.0
Gain (loss) on foreign currency contracts, net	0.0	0.0	0.0	0.0
Loss on extinguishments of debt		0.0		0.0
Interest expense	(10.0)	(10.2)	(32.0)	(30.5)
(Loss) income before income taxes	(6.1)	17.5	203.3	195.8
Noncontrolling interests’ net loss	0.0	0.0	0.0	0.0
Depreciation and amortization	21.4	17.9	62.9	53.0
Capital expenditures (including the effects of accruals)	79.7	79.1	206.5	199.7
Total assets	3,194.0	2,904.5	3,194.0	2,904.5
Short-term borrowings	118.5	50.0	118.5	50.0
Goodwill	182.1	182.1	182.1	182.1
Corporate & Other
Segment Reporting Information [Line Items]
Revenues	(1.0)	1.3	(1.2)	1.8
Cost of sales	(70.3)	37.6	(31.2)	(44.4)
Segment profit:
Operating income (loss)	63.2	(38.5)	13.4	31.3
Income (loss) from equity investees	0.0	0.0	0.0	0.0
Gain (loss) on foreign currency contracts, net	26.1	(16.0)	24.0	(16.1)
Loss on extinguishments of debt		0.0		0.0
Interest expense	(0.1)	(0.1)	(0.4)	(0.1)
(Loss) income before income taxes	89.2	(54.6)	37.0	15.1
Noncontrolling interests’ net loss	14.8	(4.4)	(7.4)	(6.5)
Depreciation and amortization	0.2	0.2	0.7	0.7
Capital expenditures (including the effects of accruals)	0.1	0.1	1.3	0.4
Total assets	275.2	290.0	275.2	290.0
Short-term borrowings	0.0	0.0	0.0	0.0
Goodwill	$ 0.0	$ 0.0	$ 0.0	$ 0.0