Segment Information - Schedule of Segment Reporting (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting Information
Revenues	$ 1,150.4	$ 1,363.7	$ 2,606.1	$ 2,200.2	$ 1,273.1	$ 1,440.9	$ 2,812.0	$ 2,125.2	$ 7,320.4	$ 7,651.2	$ 6,120.7
Cost of sales									4,323.1	4,074.9	2,837.3
Operating income (loss)	(99.0)	9.6	538.8	167.7	49.2	29.5	591.0	395.0	617.1	1,064.7	1,010.0
Income from equity investees									9.1	4.3	4.3
Loss on extinguishments of debt				(4.2)					(6.1)	0.0	(59.7)
Other non-operating income (expense), net									38.2	15.6	(29.7)
Earnings (losses) before interest expense and income taxes									658.3	1,084.6	924.9
Interest expense									(257.8)	(230.1)	(223.5)
Income tax (expense) benefit									(92.6)	(32.1)	(177.6)
Noncontrolling interests’ net (income) loss									(51.7)	(103.7)	(87.2)
Net income attributable to UGI	(51.5)	$ (1.9)	$ 245.4	$ 64.2	24.4	$ 52.4	$ 276.0	$ 365.9	256.2	718.7	436.6
Depreciation and amortization									448.1	455.1	416.3
Total assets	13,346.6				11,980.9				13,346.6	11,980.9	11,582.2
Short-term borrowings	796.3				424.9				796.3	424.9	366.9
Capital expenditures (including the effects of accruals)									707.6	597.0	624.3
Investments in equity investees	189.6				87.6				189.6	87.6	59.1
Goodwill	3,456.4				3,160.4				3,456.4	3,160.4	3,107.2
AmeriGas Propane
Segment Reporting Information
Goodwill	2,003.0				2,003.0				2,003.0	2,003.0	2,001.3
UGI International
Segment Reporting Information
Goodwill	929.8				963.7				929.8	963.7	912.2
Midstream & Marketing
Segment Reporting Information
Goodwill	341.5				11.6				341.5	11.6	11.6
Eliminations
Segment Reporting Information
Revenues									(305.4)	(370.8)	(222.7)
Cost of sales									(301.7)	(366.6)	(218.3)
Operating income (loss)									0.5	0.3	0.3
Income from equity investees									0.0	0.0	0.0
Loss on extinguishments of debt									0.0		0.0
Other non-operating income (expense), net									0.0	0.0	0.0
Earnings (losses) before interest expense and income taxes									0.5	0.3	0.3
Interest expense									0.0	0.0	0.0
Income tax (expense) benefit									(0.2)	(1.4)	(0.2)
Noncontrolling interests’ net (income) loss									0.0	0.0	0.0
Net income attributable to UGI									0.3	(1.1)	0.1
Depreciation and amortization									(0.2)	(0.3)	(0.2)
Total assets	(352.8)				(125.3)				(352.8)	(125.3)	(51.5)
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									234.6	272.6	178.2
Eliminations | UGI Utilities
Segment Reporting Information
Revenues									67.9	93.9	40.1
Operating Segments | AmeriGas Propane
Segment Reporting Information
Revenues									2,682.0	2,823.0	2,453.5
Cost of sales									1,191.3	1,314.7	1,002.9
Operating income (loss)									404.0	422.2	355.3
Income from equity investees									0.0	0.0	0.0
Loss on extinguishments of debt									0.0		0.0
Other non-operating income (expense), net									0.0	0.0	0.0
Earnings (losses) before interest expense and income taxes									404.0	422.2	355.3
Interest expense									(167.4)	(163.1)	(160.2)
Income tax (expense) benefit									(25.7)	(30.5)	(32.5)
Noncontrolling interests’ net (income) loss									(142.7)	(152.3)	(108.4)
Net income attributable to UGI									68.2	76.3	54.2
Depreciation and amortization									179.4	185.8	190.5
Total assets	4,095.3				3,933.9				4,095.3	3,933.9	4,069.4
Short-term borrowings	328.0				232.0				328.0	232.0	140.0
Capital expenditures (including the effects of accruals)									107.3	101.3	98.1
Investments in equity investees	0.0				0.0				0.0	0.0	0.0
Goodwill	2,003.0				2,003.0				2,003.0	2,003.0	2,001.3
Operating Segments | UGI International
Segment Reporting Information
Revenues									2,372.2	2,683.8	1,877.5
Cost of sales									1,416.4	1,620.1	935.3
Operating income (loss)									228.9	247.9	234.3
Income from equity investees									0.0	(0.5)	0.0
Loss on extinguishments of debt									0.0		0.0
Other non-operating income (expense), net									5.4	(7.0)	1.2
Earnings (losses) before interest expense and income taxes									234.3	240.4	235.5
Interest expense									(25.0)	(21.1)	(20.6)
Income tax (expense) benefit									(64.6)	(69.2)	(58.9)
Noncontrolling interests’ net (income) loss									0.1	3.0	(0.2)
Net income attributable to UGI									144.8	153.1	155.8
Depreciation and amortization									123.8	140.6	117.4
Total assets	2,975.2				3,279.0				2,975.2	3,279.0	3,132.0
Short-term borrowings	210.9				1.4				210.9	1.4	17.9
Capital expenditures (including the effects of accruals)									106.4	111.4	90.3
Investments in equity investees	11.6				12.8				11.6	12.8	8.1
Goodwill	929.8				963.7				929.8	963.7	912.2
Operating Segments | Midstream & Marketing
Segment Reporting Information
Revenues									1,515.7
Revenues from external customers									1,281.1	1,149.1	943.0
Cost of sales									1,241.2	1,090.8	856.7
Operating income (loss)									105.0	175.1	139.4
Income from equity investees									9.1	4.8	4.3
Loss on extinguishments of debt									0.0		0.0
Other non-operating income (expense), net									0.0	(1.2)	(0.2)
Earnings (losses) before interest expense and income taxes									114.1	178.7	143.5
Interest expense									(9.0)	(2.4)	(2.1)
Income tax (expense) benefit									(27.1)	(49.6)	(54.5)
Noncontrolling interests’ net (income) loss									0.0	0.0	0.0
Net income attributable to UGI									78.0	126.7	86.9
Depreciation and amortization									51.4	43.5	35.4
Total assets	2,744.5				1,328.9				2,744.5	1,328.9	1,165.5
Short-term borrowings	91.4				2.0				91.4	2.0	39.0
Capital expenditures (including the effects of accruals)									137.7	43.1	117.5
Investments in equity investees	178.0				74.8				178.0	74.8	51.0
Goodwill	341.5				11.6				341.5	11.6	11.6
Operating Segments | UGI Utilities
Segment Reporting Information
Revenues									1,048.6
Revenues from external customers									980.7	998.5	847.5
Cost of sales									481.3	522.9	367.3
Operating income (loss)									224.2	239.9	232.7
Income from equity investees									0.0	0.0	0.0
Loss on extinguishments of debt									0.0		0.0
Other non-operating income (expense), net									1.5	(2.4)	(4.4)
Earnings (losses) before interest expense and income taxes									225.7	237.5	228.3
Interest expense									(49.6)	(42.9)	(40.2)
Income tax (expense) benefit									(42.9)	(53.7)	(72.1)
Noncontrolling interests’ net (income) loss									0.0	0.0	0.0
Net income attributable to UGI									133.2	140.9	116.0
Depreciation and amortization									92.8	84.6	72.3
Total assets	3,559.5				3,266.6				3,559.5	3,266.6	2,994.0
Short-term borrowings	166.0				189.5				166.0	189.5	170.0
Capital expenditures (including the effects of accruals)									355.3	338.5	317.7
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									7.3
Revenues from external customers									4.4	(3.2)	(0.8)
Cost of sales									294.6	(107.0)	(106.6)
Operating income (loss)									(345.5)	(20.7)	48.0
Income from equity investees									0.0	0.0	0.0
Loss on extinguishments of debt									(6.1)		(59.7)
Other non-operating income (expense), net									31.3	26.2	(26.3)
Earnings (losses) before interest expense and income taxes									(320.3)	5.5	(38.0)
Interest expense									(6.8)	(0.6)	(0.4)
Income tax (expense) benefit									67.9	172.3	40.6
Noncontrolling interests’ net (income) loss									90.9	45.6	21.4
Net income attributable to UGI									(168.3)	222.8	23.6
Depreciation and amortization									0.9	0.9	0.9
Total assets	324.9				297.8				324.9	297.8	272.8
Short-term borrowings	0.0				0.0				0.0	0.0	0.0
Capital expenditures (including the effects of accruals)									0.9	2.7	0.7
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 & Other | AmeriGas Propane
Segment Reporting Information
Loss on extinguishments of debt									0.0		(59.7)
Corporate & Other | UGI International
Segment Reporting Information
Loss on extinguishments of debt									(6.1)		0.0
Corporate & Other | Midstream & Marketing
Segment Reporting Information
Loss on extinguishments of debt									0.0		0.0
Corporate, Intersegment Eliminations & Other
Segment Reporting Information
Revenues									2.9	$ 4.3	$ 4.4
Scenario, Adjustment | AmeriGas Propane
Segment Reporting Information
Operating income (loss)									(112.9)
Scenario, Adjustment | UGI International
Segment Reporting Information
Operating income (loss)									(4.0)			$ (29.0)
Scenario, Adjustment | Midstream & Marketing
Segment Reporting Information
Operating income (loss)									(70.1)
Scenario, Adjustment | UGI Utilities
Segment Reporting Information
Operating income (loss)									$ (8.0)