Acquisitions - Unaudited Pro Forma Revenues, Net Income, and Earnings Per Share Data (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Business Combinations [Abstract]
Revenues	$ 1,113.9	$ 1,153.5	$ 2,173.8	$ 1,679.5	$ 976.2	$ 1,130.8	$ 1,972.1	$ 1,606.6	$ 6,120.7	$ 5,685.7	$ 6,691.1
Net income (loss) attributable to UGI Corporation	$ 5.0	$ (19.0)	$ 219.9	$ 230.7	$ (43.8)	$ 60.7	$ 233.2	$ 114.6	$ 436.6	$ 364.7	$ 281.0
Earnings per common share attributable to UGI Corporation stockholders:
Basic (in dollars per share)	$ 0.03	$ (0.11)	$ 1.27	$ 1.33	$ (0.25)	$ 0.35	$ 1.35	$ 0.66	$ 2.51	$ 2.11	$ 1.62
Diluted (in dollars per share)	$ 0.03	$ (0.11)	$ 1.24	$ 1.30	$ (0.25)	$ 0.34	$ 1.33	$ 0.65	$ 2.46	$ 2.08	$ 1.60
Totalgaz SAS
Business Acquisition [Line Items]
Revenues											$ 7,065.8
Net income attributable to UGI Corporation											$ 341.2
Earnings per common share attributable to UGI Corporation stockholders:
Basic (in dollars per share)											$ 1.97
Diluted (in dollars per share)											$ 1.94