CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Millions	3 Months Ended								12 Months Ended
	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
Income Statement [Abstract]
Revenues	$ 1,124	$ 1,199	$ 2,229	$ 2,007	$ 1,150	$ 1,364	$ 2,606	$ 2,200	$ 6,559	$ 7,320	$ 7,651
Costs and expenses:
Cost of sales (excluding depreciation and amortization shown below)									3,149	4,323	4,075
Operating and administrative expenses									1,911	1,963	2,013
Impairment of Partnership tradenames and trademarks									0	0	75
Loss on disposals of Conemaugh and HVAC									54	0	0
Depreciation and amortization									484	448	455
Other operating income, net									(21)	(31)	(32)
Total costs and expenses									5,577	6,703	6,586
Operating income	69	174	362	377	(99)	9	539	168	982	617	1,065
Income (loss) from equity investees									27	9	4
Loss on extinguishments of debt				(4)					0	(6)
Other non-operating (expense) income, net									(20)	39	16
Interest expense									(322)	(258)	(230)
Income before income taxes									667	401	855
Income tax expense									(135)	(93)	(33)
Net income including noncontrolling interests	10	84	226	212	(131)	(46)	396	89	532	308	822
Deduct net income attributable to noncontrolling interests, principally in AmeriGas Partners prior to the AmeriGas Merger									0	(52)	(103)
Net income attributable to UGI Corporation	$ 9	$ 85	$ 226	$ 212	$ (52)	$ (2)	$ 246	$ 64	$ 532	$ 256	$ 719
Earnings 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:
Basic (in shares)	208,655	208,598	208,941	209,439	189,905	174,759	174,501	174,413	208,928	178,417	173,908
Diluted (in shares)	209,357	208,975	209,808	211,258	189,905	174,759	177,318	177,566	209,869	181,111	176,905