Goodwill and Intangible Assets - Changes in the Carrying Amount of Goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Goodwill
Balance at beginning of period	$ 2,989.0	$ 2,953.4
Acquisitions	78.5	41.1
Dispositions		(1.6)
Purchase accounting adjustments	(1.7)	(4.5)
Foreign currency translation	41.4	0.6
Balance at end of period	3,107.2	2,989.0
AmeriGas Propane
Goodwill
Balance at beginning of period	1,978.3	1,956.0
Acquisitions	23.0	24.2
Dispositions		0.0
Purchase accounting adjustments	0.0	(1.9)
Foreign currency translation	0.0	0.0
Balance at end of period	2,001.3	1,978.3
UGI International
Goodwill
Balance at beginning of period	817.0	803.7
Acquisitions	55.5	16.9
Dispositions		(1.6)
Purchase accounting adjustments	(1.7)	(2.6)
Foreign currency translation	41.4	0.6
Balance at end of period	912.2	817.0
Midstream & Marketing
Goodwill
Balance at beginning of period	11.6	11.6
Acquisitions	0.0	0.0
Dispositions		0.0
Purchase accounting adjustments	0.0	0.0
Foreign currency translation	0.0	0.0
Balance at end of period	11.6	11.6
UGI Utilities
Goodwill
Balance at beginning of period	182.1	182.1
Acquisitions	0.0	0.0
Dispositions		0.0
Purchase accounting adjustments	0.0	0.0
Foreign currency translation	0.0	0.0
Balance at end of period	$ 182.1	$ 182.1