Quarterly Data (unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions			3 Months Ended								12 Months Ended
	Aug. 21, 2019	Aug. 01, 2019	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
Quarterly Financial Data [Abstract]
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
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
Net income (loss) including noncontrolling interests			(130.8)	(46.5)	396.7	88.5	(7.8)	(11.7)	407.7	434.2	307.9	822.4	523.8
Net income (loss) attributable to UGI Corporation			$ (51.5)	$ (1.9)	$ 245.4	$ 64.2	$ 24.4	$ 52.4	$ 276.0	$ 365.9	$ 256.2	$ 718.7	$ 436.6
Earnings (loss) per common share attributable to UGI Corporation stockholders:
Basic (in dollars per share)			$ (0.27)	$ (0.01)	$ 1.41	$ 0.37	$ 0.14	$ 0.30	$ 1.59	$ 2.11	$ 1.44	$ 4.13	$ 2.51
Diluted (in dollars per share)			$ (0.27)	$ (0.01)	$ 1.38	$ 0.36	$ 0.14	$ 0.30	$ 1.57	$ 2.07	$ 1.41	$ 4.06	$ 2.46
Weighted-average common shares outstanding (thousands):
Basic (in shares)			189,905,000	174,759,000	174,501,000	174,413,000	174,391,000	173,991,000	173,570,000	173,670,000	178,417,000	173,908,000	173,662,000
Diluted (in shares)			189,905,000	174,759,000	177,318,000	177,566,000	177,506,000	176,807,000	176,350,000	176,948,000	181,111,000	176,905,000	177,159,000
Effect of Fourth Quarter Events [Line Items]
Loss on extinguishments of debt						$ 4.2					$ 6.1	$ 0.0	$ 59.7
Tax Cuts And Jobs Act Of 2017, increase (decrease) in net income							$ (5.8)	$ 0.8	$ 5.3	$ 166.0
2017 French Finance Bills which increased (decreased) net income												52.1
Impairment of intangible assets, finite-lived											$ 0.0	$ 75.0	$ 0.0
Trademarks and tradenames
Effect of Fourth Quarter Events [Line Items]
Impairment of intangible assets, finite-lived								14.5
French Parliament
Effect of Fourth Quarter Events [Line Items]
2017 French Finance Bills which increased (decreased) net income							$ (1.4)	$ (0.1)	$ (3.7)	$ 17.3
Common Stock | Merger Sub
Effect of Fourth Quarter Events [Line Items]
Consideration paid (in shares)	34,612,847	34,612,847									34,613,000