Goodwill and Intangible Assets - Changes in the Carrying Amount of Goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Goodwill
Balance at beginning of period	$ 3,456	$ 3,160
Acquisitions		356
Dispositions	(5)
Purchase accounting adjustments	(2)
Foreign currency translation	69	(60)
Balance at end of period	3,518	3,456
AmeriGas Propane
Goodwill
Balance at beginning of period	2,004	2,004
Acquisitions		0
Dispositions	0
Purchase accounting adjustments	0
Foreign currency translation	0	0
Balance at end of period	2,004	2,004
UGI International
Goodwill
Balance at beginning of period	930	964
Acquisitions		26
Dispositions	0
Purchase accounting adjustments	(2)
Foreign currency translation	69	(60)
Balance at end of period	997	930
Midstream & Marketing
Goodwill
Balance at beginning of period	340	10
Acquisitions		330
Dispositions	(5)
Purchase accounting adjustments	0
Foreign currency translation	0	0
Balance at end of period	335	340
UGI Utilities
Goodwill
Balance at beginning of period	182	182
Acquisitions		0
Dispositions	0
Purchase accounting adjustments	0
Foreign currency translation	0	0
Balance at end of period	$ 182	$ 182