SCHEDULE I — CONDENSED FINANCIAL INFORMATION OF REGISTRANT (PARENT COMPANY) - BALANCE SHEETS (Details) - USD ($) $ in Millions	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Current assets
Cash and cash equivalents	$ 336	$ 447	$ 452	$ 558
Prepaid expenses and other current assets	59	68
Total current assets	1,543	1,566
Other assets	854	498
Total assets	13,985	13,347	$ 11,981
Current liabilities
Current maturities of long-term debt	53	24
Total current liabilities	1,755	2,028
Long-term debt	5,981	5,780
Other noncurrent liabilities	1,413	1,123
Total liabilities	9,848	9,520
Commitments and contingencies (Note 1)
Common stockholders’ equity:
Common Stock, without par value (authorized – 450,000,000 shares; issued – 209,514,044 and 209,304,129 shares, respectively)	1,416	1,397
Retained earnings	2,908	2,653
Accumulated other comprehensive loss	(147)	(217)
Treasury stock, at cost	(49)	(16)
Total UGI Corporation stockholders’ equity	4,128	3,817
Total liabilities and equity	$ 13,985	$ 13,347
Condensed Financial Information of Registrant [Abstract]
Common stock, shares authorized (in shares)	450,000,000	450,000,000
Common stock, shares issued (in shares)	209,514,044	209,304,129
Parent Company
Current assets
Cash and cash equivalents	$ 67	$ 54
Accounts receivable – related parties	11	5
Prepaid expenses and other current assets	15	23
Total current assets	93	82
Property, plant and equipment, net	2	3
Investments in subsidiaries	4,898	4,585
Other assets	87	77
Total assets	5,080	4,747
Current liabilities
Current maturities of long-term debt	30	0
Accounts and notes payable	15	15
Accrued liabilities	29	9
Total current liabilities	74	24
Long-term debt	817	846
Other noncurrent liabilities	61	60
Total liabilities	952	930
Commitments and contingencies (Note 1)
Common stockholders’ equity:
Common Stock, without par value (authorized – 450,000,000 shares; issued – 209,514,044 and 209,304,129 shares, respectively)	1,416	1,397
Retained earnings	2,908	2,653
Accumulated other comprehensive loss	(147)	(217)
Treasury stock, at cost	(49)	(16)
Total UGI Corporation stockholders’ equity	4,128	3,817
Total liabilities and equity	$ 5,080	$ 4,747
Condensed Financial Information of Registrant [Abstract]
Common stock, shares issued (in shares)	209,514,044	209,304,129