Segment Information - Reconciliation of Partnership Adjusted EBITDA (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Segment Reporting Information [Line Items]
Net gains (losses) on commodity derivative instruments not associated with current-period transactions	$ 100	$ (141)
Midstream & Marketing | Revenues
Segment Reporting Information [Line Items]
Net gains (losses) on commodity derivative instruments not associated with current-period transactions	(1)	1
Costs associated with exit of the UGI International energy marketing business		0
Midstream & Marketing | Cost of sales
Segment Reporting Information [Line Items]
Net gains (losses) on commodity derivative instruments not associated with current-period transactions	59	(47)
Midstream & Marketing | Other operating expense (income), net
Segment Reporting Information [Line Items]
Net gains (losses) on commodity derivative instruments not associated with current-period transactions	0	0
Midstream & Marketing | Operating and administrative expenses
Segment Reporting Information [Line Items]
AmeriGas operations enhancement for growth project		0
Midstream & Marketing | Other non-operating income (expense), net
Segment Reporting Information [Line Items]
Net gains (losses) on commodity derivative instruments not associated with current-period transactions	0	0
Midstream & Marketing | Operating and administrative expenses/Other operating income, net
Segment Reporting Information [Line Items]
Costs associated with exit of the UGI International energy marketing business		0
Midstream & Marketing | Loss on disposal of UGI International energy marketing business
Segment Reporting Information [Line Items]
Costs associated with exit of the UGI International energy marketing business		0
UGI International | Revenues
Segment Reporting Information [Line Items]
Net gains (losses) on commodity derivative instruments not associated with current-period transactions	0	1
Costs associated with exit of the UGI International energy marketing business		(42)
UGI International | Cost of sales
Segment Reporting Information [Line Items]
Net gains (losses) on commodity derivative instruments not associated with current-period transactions	12	(41)
UGI International | Other operating expense (income), net
Segment Reporting Information [Line Items]
Net gains (losses) on commodity derivative instruments not associated with current-period transactions	1	(3)
UGI International | Operating and administrative expenses
Segment Reporting Information [Line Items]
AmeriGas operations enhancement for growth project		0
UGI International | Other non-operating income (expense), net
Segment Reporting Information [Line Items]
Net gains (losses) on commodity derivative instruments not associated with current-period transactions	22	(20)
UGI International | Operating and administrative expenses/Other operating income, net
Segment Reporting Information [Line Items]
Costs associated with exit of the UGI International energy marketing business		(8)
UGI International | Loss on disposal of UGI International energy marketing business
Segment Reporting Information [Line Items]
Costs associated with exit of the UGI International energy marketing business		(28)
AmeriGas Propane | Revenues
Segment Reporting Information [Line Items]
Net gains (losses) on commodity derivative instruments not associated with current-period transactions	0	0
Costs associated with exit of the UGI International energy marketing business		0
AmeriGas Propane | Cost of sales
Segment Reporting Information [Line Items]
Net gains (losses) on commodity derivative instruments not associated with current-period transactions	7	(6)
AmeriGas Propane | Other operating expense (income), net
Segment Reporting Information [Line Items]
Net gains (losses) on commodity derivative instruments not associated with current-period transactions	0	0
AmeriGas Propane | Operating and administrative expenses
Segment Reporting Information [Line Items]
AmeriGas operations enhancement for growth project		(7)
AmeriGas Propane | Other non-operating income (expense), net
Segment Reporting Information [Line Items]
Net gains (losses) on commodity derivative instruments not associated with current-period transactions	$ 0	0
AmeriGas Propane | Operating and administrative expenses/Other operating income, net
Segment Reporting Information [Line Items]
Costs associated with exit of the UGI International energy marketing business		0
AmeriGas Propane | Loss on disposal of UGI International energy marketing business
Segment Reporting Information [Line Items]
Costs associated with exit of the UGI International energy marketing business		$ 0