SCHEDULE I — CONDENSED FINANCIAL INFORMATION OF REGISTRANT (PARENT COMPANY) - BALANCE SHEETS (Details) - USD ($) $ in Millions	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Current assets
Cash and cash equivalents	$ 447.1	$ 452.6	$ 558.4	$ 502.8
Prepaid expenses and other current assets	60.0	61.6
Total current assets	1,566.2	1,888.1
Property, plant and equipment, net	6,687.8	5,808.2
Other assets	497.9	273.6
Total assets	13,346.6	11,980.9	$ 11,582.2
Current liabilities
Total current liabilities	2,026.9	1,732.1
Long-term debt	5,779.9	4,146.5
Total liabilities	9,519.4	7,880.9
Commitments and contingencies (Note 1)
Common stockholders’ equity:
Common Stock, without par value (authorized – 450,000,000 shares; issued – 209,304,129 and 174,142,997 shares, respectively)	1,396.9	1,200.8
Retained earnings	2,653.1	2,610.7
Accumulated other comprehensive loss	(216.6)	(110.4)
Treasury stock, at cost	(15.9)	(19.7)
Total UGI Corporation stockholders’ equity	3,817.5	3,681.4
Total liabilities and equity	$ 13,346.6	$ 11,980.9
Condensed Financial Information of Registrant [Abstract]
Common stock, shares authorized (in shares)	450,000,000	450,000,000
Common stock, shares issued (in shares)	209,304,129	174,142,997
Parent Company
Current assets
Cash and cash equivalents	$ 53.7	$ 13.4
Accounts receivable – related parties	5.4	12.8
Prepaid expenses and other current assets	22.8	10.5
Total current assets	81.9	36.7
Property, plant and equipment, net	3.0	2.6
Investments in subsidiaries	4,585.1	3,652.0
Other assets	77.4	71.9
Total assets	4,747.4	3,763.2
Current liabilities
Accounts and notes payable	15.4	14.9
Accrued liabilities	9.1	6.7
Total current liabilities	24.5	21.6
Long-term debt	846.0	0.0
Other noncurrent liabilities	59.4	60.2
Total liabilities	929.9	81.8
Commitments and contingencies (Note 1)
Common stockholders’ equity:
Common Stock, without par value (authorized – 450,000,000 shares; issued – 209,304,129 and 174,142,997 shares, respectively)	1,396.9	1,200.8
Retained earnings	2,653.1	2,610.7
Accumulated other comprehensive loss	(216.6)	(110.4)
Treasury stock, at cost	(15.9)	(19.7)
Total UGI Corporation stockholders’ equity	3,817.5	3,681.4
Total liabilities and equity	$ 4,747.4	$ 3,763.2
Condensed Financial Information of Registrant [Abstract]
Common stock, shares authorized (in shares)	450,000,000	450,000,000
Common stock, shares issued (in shares)	209,304,129	174,142,997