Quarterly Data (unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions			3 Months Ended								12 Months Ended
	Aug. 21, 2019	Aug. 01, 2019	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Quarterly Financial Data [Abstract]
Revenues			$ 1,124	$ 1,199	$ 2,229	$ 2,007	$ 1,150	$ 1,364	$ 2,606	$ 2,200	$ 6,559	$ 7,320	$ 7,651
Operating income (loss)			69	174	362	377	(99)	9	539	168	982	617	1,065
Net income (loss) including noncontrolling interests			10	84	226	212	(131)	(46)	396	89	532	308	822
Net income (loss) attributable to UGI Corporation			$ 9	$ 85	$ 226	$ 212	$ (52)	$ (2)	$ 246	$ 64	$ 532	$ 256	$ 719
Earnings (loss) per common share attributable to UGI Corporation stockholders:
Basic (in dollars per share)			$ 0.05	$ 0.41	$ 1.08	$ 1.01	$ (0.27)	$ (0.01)	$ 1.41	$ 0.37	$ 2.55	$ 1.44	$ 4.13
Diluted (in dollars per share)			$ 0.05	$ 0.41	$ 1.07	$ 1.00	$ (0.27)	$ (0.01)	$ 1.38	$ 0.36	$ 2.54	$ 1.41	$ 4.06
Weighted-average common shares outstanding (thousands):
Basic (in shares)			208,655,000	208,598,000	208,941,000	209,439,000	189,905,000	174,759,000	174,501,000	174,413,000	208,928,000	178,417,000	173,908,000
Diluted (in shares)			209,357,000	208,975,000	209,808,000	211,258,000	189,905,000	174,759,000	177,318,000	177,566,000	209,869,000	181,111,000	176,905,000
Effect of Fourth Quarter Events [Line Items]
Loss on extinguishments of debt						$ 4					$ 0	$ 6
Impairment of intangible assets, finite-lived											$ 0	$ 0	$ 75
Trademarks and tradenames
Effect of Fourth Quarter Events [Line Items]
Impairment of intangible assets, finite-lived				$ 37
Common Stock | Merger Sub
Effect of Fourth Quarter Events [Line Items]
Consideration paid (in shares)	34,612,847	34,613,000										34,613,000