Income Taxes - Narrative (Details) - USD ($)	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Income Tax Examination [Line Items]
Foreign tax credits	$ 25,000,000	$ 5,000,000	$ 0
Foreign tax credit carryforwards	64,000,000	76,000,000
Net operating loss carryback			15,000,000
Income taxes receivable	36,000,000	128,000,000
GILTI taxes	13,000,000	3,000,000	8,000,000
Deferred tax assets relating to operating loss carryforwards	75,000,000	48,000,000
Increase (decrease) in valuation allowance		3,000,000
Unrecognized tax benefits if recognized would impact the reported effective tax rate	26,000,000	5,000,000	3,000,000
Notional interest deduction carryover
Income Tax Examination [Line Items]
Increase (decrease) in valuation allowance	(5,000,000)	17,000,000
State Tax Rate Changes
Income Tax Examination [Line Items]
Increase (decrease) in valuation allowance	(3,000,000)	4,000,000
Future FTC's realizable
Income Tax Examination [Line Items]
Increase (decrease) in valuation allowance	(16,000,000)	6,000,000
Foreign Net Operating Loss Carry Forwards
Income Tax Examination [Line Items]
Increase (decrease) in valuation allowance	11,000,000	4,000,000
Capital Losses
Income Tax Examination [Line Items]
Increase (decrease) in valuation allowance	(22,000,000)
Disallowed Interest
Income Tax Examination [Line Items]
Increase (decrease) in valuation allowance	19,000,000
AmeriGas Propane
Income Tax Examination [Line Items]
Operating loss carryforwards	9,000,000
Other Subsidiaries
Income Tax Examination [Line Items]
Deferred tax assets relating to operating loss carryforwards	75,000,000
Fiscal 2021
Income Tax Examination [Line Items]
Income taxes receivable	37,000,000	37,000,000
Effects of tax rate changes – State, net of federal benefit
Income Tax Examination [Line Items]
Benefit from legislation	4,000,000	20,000,000
Decrease in income tax expense due to state tax flow through of accelerated depreciation	11,000,000	$ 10,000,000	9,000,000
Operating loss carryforwards	1,071,000,000
Foreign | Flaga
Income Tax Examination [Line Items]
Operating loss carryforwards	6,000,000
Foreign | UGI France
Income Tax Examination [Line Items]
Operating loss carryforwards	23,000,000
Foreign | Italy
Income Tax Examination [Line Items]
Foreign tax credit carryforwards			$ 23,000,000
Foreign | Tax and Customs Administration, Netherlands
Income Tax Examination [Line Items]
Operating loss carryforwards	44,000,000
Foreign | Administration of the Treasury, Belgium
Income Tax Examination [Line Items]
Operating loss carryforwards	10,000,000
Foreign | Her Majesty's Revenue and Customs (HMRC)
Income Tax Examination [Line Items]
Operating loss carryforwards	$ 5,000,000