Segment Information - Reconciliation of Partnership Adjusted EBITDA (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Segment Reporting Information [Line Items]
Net gains (losses) on commodity derivative instruments not associated with current-period transactions	$ (10)	$ (1,682)	$ 648
Loss on extinguishments of debt	(9)	(9)	(11)
Loss associated with impairment of AmeriGas Propane goodwill	(195)	(656)	0
Loss on disposal of UGID	(95)	(221)	0
Midstream & Marketing
Segment Reporting Information [Line Items]
AmeriGas operations enhancement for growth project	0	0	0
Restructuring costs	(1)		(1)
Loss on extinguishments of debt	(1)	0	0
Impairments of equity method investments and assets	0		(35)
Loss associated with impairment of AmeriGas Propane goodwill	0	0
Loss on disposal of UGID	(66)
Midstream & Marketing | Revenues
Segment Reporting Information [Line Items]
Net gains (losses) on commodity derivative instruments not associated with current-period transactions	0	6	(4)
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	63	(236)	(21)
Midstream & Marketing | Other operating income, net
Segment Reporting Information [Line Items]
Net gains (losses) on commodity derivative instruments not associated with current-period transactions	0		0
Midstream & Marketing | Other non-operating (expense) income, net
Segment Reporting Information [Line Items]
Net gains (losses) on commodity derivative instruments not associated with current-period transactions	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
Midstream & Marketing | Revenues; Operating and administrative expenses
Segment Reporting Information [Line Items]
Costs associated with exit of the UGI International energy marketing business		0
Midstream & Marketing | Loss on disposals of businesses
Segment Reporting Information [Line Items]
Costs associated with exit of the UGI International energy marketing business	0	0
UGI International
Segment Reporting Information [Line Items]
AmeriGas operations enhancement for growth project	0	0	0
Restructuring costs	(57)		(9)
Loss on extinguishments of debt	0	0	(11)
Impairments of equity method investments and assets	(33)		(5)
Loss associated with impairment of AmeriGas Propane goodwill	0	0
Loss on disposal of UGID	0
UGI International | Revenues
Segment Reporting Information [Line Items]
Net gains (losses) on commodity derivative instruments not associated with current-period transactions	1	4	9
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	(5)	(1,402)	797
UGI International | Other operating income, net
Segment Reporting Information [Line Items]
Net gains (losses) on commodity derivative instruments not associated with current-period transactions	(3)		2
UGI International | Other non-operating (expense) income, net
Segment Reporting Information [Line Items]
Net gains (losses) on commodity derivative instruments not associated with current-period transactions	(31)	(38)	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	(13)
UGI International | Revenues; Operating and administrative expenses
Segment Reporting Information [Line Items]
Costs associated with exit of the UGI International energy marketing business		(27)
UGI International | Loss on disposals of businesses
Segment Reporting Information [Line Items]
Costs associated with exit of the UGI International energy marketing business	(29)	(221)
AmeriGas Propane
Segment Reporting Information [Line Items]
AmeriGas operations enhancement for growth project	(25)	(24)	(5)
Restructuring costs	(1)		(16)
Loss on extinguishments of debt	(8)	(9)	0
Impairments of equity method investments and assets	0		0
Loss associated with impairment of AmeriGas Propane goodwill	(195)	(656)
Loss on disposal of UGID	0
AmeriGas Propane | Revenues
Segment Reporting Information [Line Items]
Net gains (losses) 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 gains (losses) on commodity derivative instruments not associated with current-period transactions	21	(16)	(185)
AmeriGas Propane | Other operating income, net
Segment Reporting Information [Line Items]
Net gains (losses) on commodity derivative instruments not associated with current-period transactions	0		0
AmeriGas Propane | Other non-operating (expense) income, net
Segment Reporting Information [Line Items]
Net gains (losses) on commodity derivative instruments not associated with current-period transactions	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
AmeriGas Propane | Revenues; Operating and administrative expenses
Segment Reporting Information [Line Items]
Costs associated with exit of the UGI International energy marketing business		0
AmeriGas Propane | Loss on disposals of businesses
Segment Reporting Information [Line Items]
Costs associated with exit of the UGI International energy marketing business	$ 0	$ 0