Condensed Financial Information of Registrant (Parent Company) - Statements of Income (Details) - USD ($) $ / shares in Units, shares in Thousands, $ 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
Condensed Financial Statements, Captions
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
Costs and Expenses
Operating and administrative expenses									1,857.8	1,865.9	1,773.9
Other operating income, net									(10.5)	(22.4)	(44.4)
Total costs and expenses									5,116.5	4,697.7	5,856.2
Operating income	27.6	(2.8)	513.2	466.2	(88.6)	155.7	615.4	305.5	1,004.2	988.0	834.9
Income tax (benefit) expense									177.6	221.2	177.8
Equity in income of unconsolidated subsidiaries	1.3	0.9	2.3	(0.2)	(0.1)	0.0	0.0	(0.1)	4.3	(0.2)	(1.2)
Net income 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
Comprehensive income attributable to UGI Corporation									$ 497.9	$ 324.6	$ 187.6
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
Weighted - average common shares outstanding (thousands):
Basic (in shares)									173,662	173,154	173,115
Diluted (in shares)									177,159	175,572	175,667
Parent Company
Condensed Financial Statements, Captions
Revenues									$ 0.0	$ 0.0	$ 0.0
Costs and Expenses
Operating and administrative expenses									46.3	45.7	48.7
Other operating income, net									(45.9)	(45.3)	(48.5)
Total costs and expenses									0.4	0.4	0.2
Operating income									(0.4)	(0.4)	(0.2)
Intercompany interest income									0.0	0.1	0.1
Loss before income taxes									(0.4)	(0.3)	(0.1)
Income tax (benefit) expense									(5.7)	(4.0)	1.9
Income (loss) before equity in income of unconsolidated subsidiaries									5.3	3.7	(2.0)
Equity in income of unconsolidated subsidiaries									431.3	361.0	283.0
Net income attributable to UGI Corporation									436.6	364.7	281.0
Other comprehensive income (loss)									1.3	(1.1)	0.1
Equity in other comprehensive income (loss) of unconsolidated subsidiaries									60.0	(39.0)	(93.5)
Comprehensive income attributable to UGI Corporation									$ 497.9	$ 324.6	$ 187.6
Earnings per common share attributable to UGI Corporation stockholders:
Basic (in dollars per share)									$ 2.51	$ 2.11	$ 1.62
Diluted (in dollars per share)									$ 2.46	$ 2.08	$ 1.60
Weighted - average common shares outstanding (thousands):
Basic (in shares)									173,662	173,154	173,115
Diluted (in shares)									177,159	175,572	175,667