Common Stock and Equity-Based Compensation - Stock Option Awards (Details) - UGI Stock Option Awards - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Shares
Shares under option - beginning balance (in shares)	8,488,451	9,255,377	8,957,290
Granted (in shares)	1,343,800	1,510,625	1,336,985
Canceled (in shares)	(60,236)	(84,213)	(85,365)
Exercised (in shares)	(990,267)	(2,193,338)	(953,533)
Shares under option - ending balance (in shares)	8,781,748	8,488,451	9,255,377	8,957,290
Weighted Average Option Price
Shares under option - beginning balance (in dollars per share)	$ 26.68	$ 23.97	$ 21.44
Granted (in dollars per share)	46.51	34.67	37.70
Canceled (in dollars per share)	41.86	34.13	30.45
Exercised (in dollars per share)	21.40	20.38	19.10
Shares under option - ending balance (in dollars per share)	$ 30.20	$ 26.68	$ 23.97	$ 21.44
Total Intrinsic Value
Shares under option - beginning balance	$ 157.6	$ 104.5	$ 113.3
Exercised	26.7	40.1	15.4
Shares under option - beginning balance	$ 146.7	$ 157.6	$ 104.5	$ 113.3
Weighted Average Contract Term (Years)
Weighted average contract term (in years)	6 years 3 months 18 days	6 years 7 months	6 years 7 months 18 days	7 years
Options Exercisable
Options exercisable (in shares)	5,973,668	5,522,370	6,050,946
Option exercisable (in dollars per share)	$ 25.53	$ 22.94	$ 20.74
Option exercisable	$ 127.4
Option exercisable (in years)	5 years 3 months 18 days
Options Not Exercisable
Options not exercisable (in shares)	2,808,080
Options not exercisable (in dollars per share)	$ 40.13
Options not exercisable	$ 19.3
Options not exercisable (in years)	7 years 9 months 18 days