Segment Information - Schedule of Segment Reporting Information (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Jun. 30, 2017	Mar. 31, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Sep. 30, 2016
Segment Reporting Information
Revenues	$ 1,153.5		$ 1,130.8	$ 5,006.8	$ 4,709.5
Cost of sales	618.5		433.0	2,337.1	1,943.9
Segment profit:
Operating (loss) income	(2.8)		155.7	976.6	1,076.6
Income (loss) from equity investees	0.9		0.0	3.0	(0.1)
Losses on foreign currency contracts, net	(16.2)		0.0	(16.1)	0.0
Loss on extinguishments of debt	(4.4)		(37.1)	(59.7)	(37.1)
Interest expense	(56.8)		(56.4)	(168.0)	(171.6)
Income (loss) before income taxes	(79.3)		62.2	735.8	867.8
Noncontrolling interests’ net (loss) income	(43.2)		(32.1)	108.9	196.0
Depreciation and amortization	104.1		98.1	301.5	299.4
Capital expenditures (including the effects of accruals)	140.9		137.4	440.7	384.8
Total assets	11,246.4		11,103.9	11,246.4	11,103.9	$ 10,847.2
Short-term borrowings	163.9		144.0	163.9	144.0	291.7
Goodwill	3,032.3		2,981.3	3,032.3	2,981.3	$ 2,989.0
Eliminations
Segment Reporting Information
Revenues	(36.9)		(17.5)	(201.2)	(116.7)
Cost of sales	(36.2)		(16.7)	(198.8)	(114.3)
Segment profit:
Operating (loss) income	0.1		0.1	0.2	0.2
Income (loss) from equity investees	0.0		0.0	0.0	0.0
Losses on foreign currency contracts, net	0.0			0.0
Loss on extinguishments of debt	0.0		0.0	0.0	0.0
Interest expense	0.0		0.0	0.0	0.0
Income (loss) before income taxes	0.1		0.1	0.2	0.2
Noncontrolling interests’ net (loss) income	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	(53.0)		(82.6)	(53.0)	(82.6)
Short-term borrowings	0.0		0.0	0.0	0.0
Goodwill	0.0		0.0	0.0	0.0
Operating Segments | AmeriGas Propane
Segment Reporting Information
Revenues	467.5		446.7	2,008.3	1,918.3
Cost of sales	197.5		170.8	814.0	712.2
Segment profit:
Operating (loss) income	4.6		18.3	373.8	398.3
Income (loss) from equity investees	0.0		0.0	0.0	0.0
Losses on foreign currency contracts, net	0.0			0.0
Loss on extinguishments of debt	(4.4)		(37.1)	(59.7)	(37.1)
Interest expense	(40.6)		(40.9)	(120.6)	(122.7)
Income (loss) before income taxes	(40.4)		(59.7)	193.5	238.5
Partnership Adjusted EBITDA	58.4		64.6	514.7	537.7
Noncontrolling interests’ net (loss) income	(38.5)		(52.4)	115.4	150.9
Depreciation and amortization	46.2		46.4	135.8	143.0
Capital expenditures (including the effects of accruals)	20.9		18.7	74.5	74.5
Total assets	4,045.7		4,376.1	4,045.7	4,376.1
Short-term borrowings	75.5		11.4	75.5	11.4
Goodwill	2,001.4		1,978.2	2,001.4	1,978.2
Operating Segments | UGI International
Segment Reporting Information
Revenues	351.3		395.5	1,511.1	1,552.4
Cost of sales	178.2		179.7	749.3	753.5
Segment profit:
Operating (loss) income	0.5		33.5	210.4	230.1
Income (loss) from equity investees	0.1		0.0	(0.2)	(0.1)
Losses on foreign currency contracts, net	(0.2)			0.0
Loss on extinguishments of debt	0.0		0.0	0.0	0.0
Interest expense	(5.6)		(5.8)	(15.2)	(18.8)
Income (loss) before income taxes	(5.2)		27.7	195.0	211.2
Noncontrolling interests’ net (loss) income	(0.3)		(0.1)	0.0	0.1
Depreciation and amortization	31.1		27.4	86.6	82.9
Capital expenditures (including the effects of accruals)	19.1		25.9	62.1	69.2
Total assets	2,887.7		2,899.5	2,887.7	2,899.5
Short-term borrowings	8.4		2.6	8.4	2.6
Goodwill	837.3		809.5	837.3	809.5
Operating Segments | Midstream & Marketing
Segment Reporting Information
Revenues	222.8		166.0	916.3	691.7
Cost of sales	189.4		124.1	691.0	468.3
Segment profit:
Operating (loss) income	2.8		11.3	134.6	132.0
Income (loss) from equity investees	0.8		0.0	3.2	0.0
Losses on foreign currency contracts, net	0.0			0.0
Loss on extinguishments of debt	0.0		0.0	0.0	0.0
Interest expense	(0.3)		(0.4)	(1.6)	(1.7)
Income (loss) before income taxes	3.3		10.9	136.2	130.3
Noncontrolling interests’ net (loss) income	0.0		0.0	0.0	0.0
Depreciation and amortization	8.8		7.6	25.6	22.7
Capital expenditures (including the effects of accruals)	21.7		36.3	104.0	75.0
Total assets	1,171.5		998.0	1,171.5	998.0
Short-term borrowings	30.0		0.0	30.0	0.0
Goodwill	11.5		11.5	11.5	11.5
Operating Segments | UGI Utilities
Segment Reporting Information
Revenues	146.6		140.3	768.0	660.3
Cost of sales	52.0		44.4	326.0	257.3
Segment profit:
Operating (loss) income	27.7		29.8	226.3	192.6
Income (loss) from equity investees	0.0		0.0	0.0	0.0
Losses on foreign currency contracts, net	0.0			0.0
Loss on extinguishments of debt	0.0		0.0	0.0	0.0
Interest expense	(10.2)		(9.1)	(30.5)	(27.9)
Income (loss) before income taxes	17.5		20.7	195.8	164.7
Noncontrolling interests’ net (loss) income	0.0		0.0	0.0	0.0
Depreciation and amortization	17.9		16.6	53.0	50.3
Capital expenditures (including the effects of accruals)	79.1		56.5	199.7	166.1
Total assets	2,904.5		2,697.3	2,904.5	2,697.3
Short-term borrowings	50.0		130.0	50.0	130.0
Goodwill	182.1		182.1	182.1	182.1
Corporate & Other
Segment Reporting Information
Revenues	2.2		(0.2)	4.3	3.5
Cost of sales	37.6		(69.3)	(44.4)	(133.1)
Segment profit:
Operating (loss) income	(38.5)		62.7	31.3	123.4
Income (loss) from equity investees	0.0		0.0	0.0	0.0
Losses on foreign currency contracts, net	(16.0)			(16.1)
Loss on extinguishments of debt	0.0		0.0	0.0	0.0
Interest expense	(0.1)		(0.2)	(0.1)	(0.5)
Income (loss) before income taxes	(54.6)		62.5	15.1	122.9
Noncontrolling interests’ net (loss) income	(4.4)		20.4	(6.5)	45.0
Depreciation and amortization	0.2		0.2	0.7	0.7
Capital expenditures (including the effects of accruals)	0.1		0.0	0.4	0.0
Total assets	290.0		215.6	290.0	215.6
Short-term borrowings	0.0		0.0	0.0	0.0
Goodwill	0.0		0.0	0.0	0.0
Gains (losses) on unsettled commodity derivative instruments, net	$ (52.7)		$ 67.9	$ 28.9	$ 133.0
Corporate & Other | Private Equity Partnership That Invests in Renewable Energy Companies
Segment profit:
Other-than-temporary impairment of investment		$ 7.0