Segment Information - Reconciliation of Partnership Adjusted EBITDA (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023
Segment Reporting Information [Line Items]
Net (losses) gains on commodity derivative instruments not associated with current-period transactions			$ (54)	$ (1,713)
Midstream & Marketing | Revenues
Segment Reporting Information [Line Items]
Net (losses) gains on commodity derivative instruments not associated with current-period transactions		$ 4	1	6
Costs associated with exit of the UGI International energy marketing business			0
Midstream & Marketing | Cost of sales
Segment Reporting Information [Line Items]
Net (losses) gains on commodity derivative instruments not associated with current-period transactions	$ 41	(78)	(6)	(261)
Midstream & Marketing | Other operating income, net
Segment Reporting Information [Line Items]
Net (losses) gains on commodity derivative instruments not associated with current-period transactions	0	0	0	0
Impairment of assets	0		0
Midstream & Marketing | Operating and administrative expenses
Segment Reporting Information [Line Items]
Restructuring costs	0		0
AmeriGas operations enhancement for growth project	0	0	0	0
Costs associated with exit of the UGI International energy marketing business				0
Midstream & Marketing | Other non-operating income (expense), net
Segment Reporting Information [Line Items]
Net (losses) gains on commodity derivative instruments not associated with current-period transactions	0	0	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		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	0
UGI International | Revenues
Segment Reporting Information [Line Items]
Net (losses) gains on commodity derivative instruments not associated with current-period transactions		1	1	3
Costs associated with exit of the UGI International energy marketing business			(42)
UGI International | Cost of sales
Segment Reporting Information [Line Items]
Net (losses) gains on commodity derivative instruments not associated with current-period transactions	53	(235)	12	(1,404)
UGI International | Other operating income, net
Segment Reporting Information [Line Items]
Net (losses) gains on commodity derivative instruments not associated with current-period transactions	1	(1)	(2)	(3)
Impairment of assets	(7)		(7)
UGI International | Operating and administrative expenses
Segment Reporting Information [Line Items]
Restructuring costs	(34)		(34)
AmeriGas operations enhancement for growth project	0	0	0	0
Costs associated with exit of the UGI International energy marketing business				19
UGI International | Other non-operating income (expense), net
Segment Reporting Information [Line Items]
Net (losses) gains on commodity derivative instruments not associated with current-period transactions	1	(10)	(19)	(50)
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	(2)		(10)
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)	215
AmeriGas Propane | Revenues
Segment Reporting Information [Line Items]
Net (losses) gains on commodity derivative instruments not associated with current-period transactions		0	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 (losses) gains on commodity derivative instruments not associated with current-period transactions	34	8	28	(4)
AmeriGas Propane | Other operating income, net
Segment Reporting Information [Line Items]
Net (losses) gains on commodity derivative instruments not associated with current-period transactions	0	0	0	0
Impairment of assets	0		0
AmeriGas Propane | Operating and administrative expenses
Segment Reporting Information [Line Items]
Restructuring costs	0		0
AmeriGas operations enhancement for growth project	(6)	(6)	(13)	(13)
Costs associated with exit of the UGI International energy marketing business				0
AmeriGas Propane | Other non-operating income (expense), net
Segment Reporting Information [Line Items]
Net (losses) gains on commodity derivative instruments not associated with current-period transactions	0	$ 0	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		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	$ 0