Segment Information - Schedule of Segment Reporting (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Segment Reporting Information
Revenues	$ 1,113.9	$ 1,153.5	$ 2,173.8	$ 1,679.5	$ 976.2	$ 1,130.8	$ 1,972.1	$ 1,606.6	$ 6,120.7	$ 5,685.7	$ 6,691.1
Cost of sales									2,837.3	2,437.5	3,736.5
Operating income	27.6	(2.8)	513.2	466.2	(88.6)	155.7	615.4	305.5	1,004.2	988.0	834.9
Income (loss) from equity investees	1.3	0.9	2.3	(0.2)	(0.1)	0.0	0.0	(0.1)	4.3	(0.2)	(1.2)
Losses on foreign currency contracts, net									(23.9)	0.0	0.0
Loss on extinguishments of debt	0.0	(4.4)	(22.1)	(33.2)	(11.8)	(37.1)	0.0	0.0	(59.7)	(48.9)	0.0
Interest expense									(223.5)	(228.9)	(241.9)
Income before income taxes									701.4	710.0	591.8
Net income (loss) attributable to UGI	5.0	$ (19.0)	$ 219.9	$ 230.7	(43.8)	$ 60.7	$ 233.2	$ 114.6	436.6	364.7	281.0
Depreciation and amortization									416.3	400.9	374.1
Noncontrolling interests’ net income (loss)									87.2	124.1	133.0
Total assets	11,582.2				10,847.2				11,582.2	10,847.2	10,514.2
Short-term borrowings	366.9				291.7				366.9	291.7	189.9
Capital expenditures (including the effects of accruals)									624.3	604.6	475.4
Investments in equity investees	59.1				25.9				59.1	25.9	16.2
Goodwill	3,107.2				2,989.0				3,107.2	2,989.0	2,953.4
AmeriGas Propane
Segment Reporting Information
Goodwill	2,001.3				1,978.3				2,001.3	1,978.3	1,956.0
UGI International
Segment Reporting Information
Goodwill	912.2				817.0				912.2	817.0	803.7
Midstream & Marketing
Segment Reporting Information
Goodwill	11.6				11.6				11.6	11.6	11.6
Eliminations
Segment Reporting Information
Revenues									(222.7)	(133.9)	(213.6)
Cost of sales									(218.3)	(131.5)	(209.8)
Operating income									0.3	0.2	(0.9)
Income (loss) from equity investees									0.0	0.0	0.0
Losses on foreign currency contracts, net									0.0
Loss on extinguishments of debt									0.0	0.0
Interest expense									0.0	0.0	0.0
Income before income taxes									0.3	0.2	(0.9)
Net income (loss) attributable to UGI									0.1	0.1	(0.6)
Depreciation and amortization									(0.2)	(0.2)	0.0
Noncontrolling interests’ net income (loss)									0.0	0.0	0.0
Total assets	(51.5)				(136.6)				(51.5)	(136.6)	(90.4)
Short-term borrowings	0.0				0.0				0.0	0.0	0.0
Capital expenditures (including the effects of accruals)									0.0	0.0	0.0
Investments in equity investees	0.0				0.0				0.0	0.0	0.0
Goodwill	0.0				0.0				0.0	0.0	0.0
Eliminations | AmeriGas Propane
Segment Reporting Information
Revenues									0.0	0.0	0.0
Eliminations | UGI International
Segment Reporting Information
Revenues									0.0	0.0	0.0
Eliminations | Midstream & Marketing
Segment Reporting Information
Revenues									178.2	114.3	151.3
Eliminations | UGI Utilities
Segment Reporting Information
Revenues									40.1	17.1	59.7
Operating Segments | AmeriGas Propane
Segment Reporting Information
Revenues									2,453.5	2,311.8	2,885.3
Cost of sales									1,002.9	864.8	1,340.0
Operating income									355.3	356.3	427.6
Income (loss) from equity investees									0.0	0.0	0.0
Losses on foreign currency contracts, net									0.0
Loss on extinguishments of debt									(59.7)	(48.9)	0.0
Interest expense									(160.2)	(164.1)	(162.8)
Income before income taxes									135.4	143.3	264.8
Net income (loss) attributable to UGI									44.6	43.2	61.0
Depreciation and amortization									190.5	190.0	194.9
Noncontrolling interests’ net income (loss)									64.4	75.9	167.9
Partnership Adjusted EBITDA									551.3	543.0	619.2
Total assets	4,069.4				4,071.8				4,069.4	4,071.8	4,128.4
Short-term borrowings	140.0				153.2				140.0	153.2	68.1
Capital expenditures (including the effects of accruals)									98.1	101.7	102.0
Investments in equity investees	0.0				0.0				0.0	0.0	0.0
Goodwill	2,001.3				1,978.3				2,001.3	1,978.3	1,956.0
Operating Segments | UGI International
Segment Reporting Information
Revenues									1,877.5	1,868.8	1,808.5
Cost of sales									935.3	903.8	1,120.0
Operating income									195.7	206.6	112.8
Income (loss) from equity investees									0.0	(0.2)	(1.2)
Losses on foreign currency contracts, net									(0.1)
Loss on extinguishments of debt									0.0	0.0
Interest expense									(20.6)	(24.4)	(35.2)
Income before income taxes									175.0	182.0	76.4
Net income (loss) attributable to UGI									158.6	111.6	52.7
Depreciation and amortization									117.4	112.4	86.9
Noncontrolling interests’ net income (loss)									0.2	0.0	(0.1)
Total assets	3,132.0				2,865.1				3,132.0	2,865.1	2,860.9
Short-term borrowings	17.9				0.5				17.9	0.5	0.6
Capital expenditures (including the effects of accruals)									90.3	99.9	87.5
Investments in equity investees	8.1				8.5				8.1	8.5	9.8
Goodwill	912.2				817.0				912.2	817.0	803.7
Operating Segments | Midstream & Marketing
Segment Reporting Information
Revenues									943.0	752.3	1,012.3
Cost of sales									856.7	602.2	854.6
Operating income									139.2	146.7	182.6
Income (loss) from equity investees									4.3	0.0	0.0
Losses on foreign currency contracts, net									0.0
Loss on extinguishments of debt									0.0	0.0
Interest expense									(2.1)	(2.1)	(2.1)
Income before income taxes									141.4	144.6	180.5
Net income (loss) attributable to UGI									86.9	87.1	107.5
Depreciation and amortization									35.4	30.6	28.0
Noncontrolling interests’ net income (loss)									0.0	0.0	0.0
Total assets	1,165.5				1,038.2				1,165.5	1,038.2	969.6
Short-term borrowings	39.0				25.5				39.0	25.5	49.5
Capital expenditures (including the effects of accruals)									117.5	140.4	88.0
Investments in equity investees	51.0				17.4				51.0	17.4	6.4
Goodwill	11.6				11.6				11.6	11.6	11.6
Operating Segments | UGI Utilities
Segment Reporting Information
Revenues									847.5	751.4	981.9
Cost of sales									367.3	289.8	510.8
Operating income									228.3	200.9	241.7
Income (loss) from equity investees									0.0	0.0	0.0
Losses on foreign currency contracts, net									0.0
Loss on extinguishments of debt									0.0	0.0
Interest expense									(40.2)	(37.6)	(41.1)
Income before income taxes									188.1	163.3	200.6
Net income (loss) attributable to UGI									116.0	97.4	121.1
Depreciation and amortization									72.3	67.3	63.5
Noncontrolling interests’ net income (loss)									0.0	0.0	0.0
Total assets	2,994.0				2,743.1				2,994.0	2,743.1	2,506.0
Short-term borrowings	170.0				112.5				170.0	112.5	71.7
Capital expenditures (including the effects of accruals)									317.7	262.5	197.7
Investments in equity investees	0.0				0.0				0.0	0.0	0.0
Goodwill	182.1				182.1				182.1	182.1	182.1
Corporate & Other
Segment Reporting Information
Revenues									(0.8)	1.4	3.1
Cost of sales									(106.6)	(91.6)	120.9
Operating income									85.4	77.3	(128.9)
Income (loss) from equity investees									0.0	0.0	0.0
Losses on foreign currency contracts, net									(23.8)
Loss on extinguishments of debt									0.0	0.0
Interest expense									(0.4)	(0.7)	(0.7)
Income before income taxes									61.2	76.6	(129.6)
Net income (loss) attributable to UGI									30.4	25.3	(60.7)
Depreciation and amortization									0.9	0.8	0.8
Noncontrolling interests’ net income (loss)									22.6	48.2	(34.8)
Total assets	272.8				265.6				272.8	265.6	139.7
Short-term borrowings	0.0				0.0				0.0	0.0	0.0
Capital expenditures (including the effects of accruals)									0.7	0.1	0.2
Investments in equity investees	0.0				0.0				0.0	0.0	0.0
Goodwill	$ 0.0				$ 0.0				0.0	0.0	0.0
Corporate, Intersegment Eliminations & Other
Segment Reporting Information
Revenues									$ 4.4	$ 2.5	$ 2.6