Condensed Financial Information of Registrant (Parent Company) - Statements of Cash Flows (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Condensed Financial Statements, Captions
NET CASH PROVIDED BY OPERATING ACTIVITIES	$ 964.4	$ 969.7	$ 1,163.8
CASH FLOWS FROM INVESTING ACTIVITIES
Expenditures for property, plant and equipment	(638.9)	(563.8)	(490.6)
Net cash used by investing activities	(763.4)	(558.6)	(976.3)
CASH FLOWS FROM FINANCING ACTIVITIES
Payment of dividends on Common Stock	(168.9)	(160.7)	(153.5)
Repurchases of UGI Common Stock	(43.3)	(47.6)	(34.1)
Issuances of Common Stock	11.0	13.7	11.9
Other	(0.8)	15.5	(3.5)
Net cash used by financing activities	(146.6)	(275.1)	(217.1)
Cash and cash equivalents increase (decrease)	55.6	133.1	(49.8)
Cash and cash equivalents:
End of year	558.4	502.8	369.7
Beginning of year	502.8	369.7	419.5
Increase (decrease)	55.6	133.1	(49.8)
Parent Company
Condensed Financial Statements, Captions
NET CASH PROVIDED BY OPERATING ACTIVITIES	253.2	195.6	277.2
CASH FLOWS FROM INVESTING ACTIVITIES
Expenditures for property, plant and equipment	(0.4)	0.0	0.0
Net investments in unconsolidated subsidiaries	(40.7)	(8.9)	(104.8)
Net cash used by investing activities	(41.1)	(8.9)	(104.8)
CASH FLOWS FROM FINANCING ACTIVITIES
Payment of dividends on Common Stock	(168.9)	(160.7)	(153.5)
Repurchases of UGI Common Stock	(43.3)	(47.6)	(34.1)
Issuances of Common Stock	11.0	24.5	16.8
Other	0.1	0.0	(0.5)
Net cash used by financing activities	(201.1)	(183.8)	(171.3)
Cash and cash equivalents increase (decrease)	11.0	2.9	1.1
Cash and cash equivalents:
End of year	15.8	4.8	1.9
Beginning of year	4.8	1.9	0.8
Increase (decrease)	11.0	2.9	1.1
Dividends from unconsolidated subsidiaries	$ 241.9	$ 193.1	$ 271.6