SCHEDULE I — CONDENSED FINANCIAL INFORMATION OF REGISTRANT (PARENT COMPANY) - BALANCE SHEETS (Details) - USD ($) $ in Millions	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Current assets
Cash and cash equivalents	$ 855	$ 336	$ 447
Prepaid expenses and other current assets	101	59
Total current assets	3,270	1,543
Other assets	831	854
Total assets	16,723	13,985	$ 13,347
Current liabilities
Current maturities of long-term debt	110	53
Total current liabilities	2,297	1,755
Long-term debt	6,339	5,981
Other noncurrent liabilities	1,381	1,413
Total liabilities	11,192	9,848
Commitments and contingencies (Note 1)
Equity:
Preferred Stock, without par value (authorized 5,000,000 shares; issued 220,000 and 0 Series A shares, respectively)	213	0
Common Stock, without par value (authorized – 450,000,000 shares; issued – 209,843,296 and 209,514,044 shares, respectively)	1,394	1,416
Retained earnings	4,081	2,908
Accumulated other comprehensive loss	(140)	(147)
Treasury stock, at cost	(26)	(49)
Total UGI Corporation stockholders’ equity	5,522	4,128
Total liabilities and equity	$ 16,723	$ 13,985
Condensed Financial Information of Registrant [Abstract]
UGI Preferred Stock, without par value, shares authorized (in shares)	5,000,000	5,000,000
Preferred Stock, shares issued (in shares)	220,000	0
Common Stock, shares authorized (in shares)	450,000,000	450,000,000
Common Stock, shares issued (in shares)	209,843,296	209,514,044
Parent Company
Current assets
Cash and cash equivalents	$ 14	$ 67
Accounts receivable – related parties	18	11
Prepaid expenses and other current assets	11	15
Total current assets	43	93
Property, plant and equipment, net	2	2
Investments in subsidiaries	6,479	4,898
Other assets	107	87
Total assets	6,631	5,080
Current liabilities
Current maturities of long-term debt	70	30
Accounts and notes payable	24	15
Accrued liabilities	62	29
Total current liabilities	156	74
Long-term debt	875	817
Other noncurrent liabilities	78	61
Total liabilities	1,109	952
Commitments and contingencies (Note 1)
Equity:
Preferred Stock, without par value (authorized 5,000,000 shares; issued 220,000 and 0 Series A shares, respectively)	213	0
Common Stock, without par value (authorized – 450,000,000 shares; issued – 209,843,296 and 209,514,044 shares, respectively)	1,394	1,416
Retained earnings	4,081	2,908
Accumulated other comprehensive loss	(140)	(147)
Treasury stock, at cost	(26)	(49)
Total UGI Corporation stockholders’ equity	5,522	4,128
Total liabilities and equity	$ 6,631	$ 5,080
Condensed Financial Information of Registrant [Abstract]
Common Stock, shares authorized (in shares)	450,000,000	450,000,000
Common Stock, shares issued (in shares)	209,843,296	209,514,044