Segment Information - Corporate and Other segment information (Details) - USD ($)	3 Months Ended		12 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Segment Reporting Information [Line Items]
Net gains (losses) on commodity derivative instruments not associated with current-period transactions			$ (1,682,000,000)	$ 648,000,000	$ 1,398,000,000
Loss on extinguishment of debt			(9,000,000)	(11,000,000)	0
Loss associated with impairment of AmeriGas Propane goodwill			(656,000,000)	0	0
Impairment of customer relationship intangible					(20,000,000)
Costs associated with exit of the UGI International energy marketing business			(221,000,000)	0	$ 0
Restructuring, Incurred Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]
AmeriGas Propane
Segment Reporting Information [Line Items]
Loss associated with impairment of AmeriGas Propane goodwill	$ (656,000,000)	$ (656,000,000)	(656,000,000)
UGI International
Segment Reporting Information [Line Items]
Loss associated with impairment of AmeriGas Propane goodwill			0
Midstream & Marketing
Segment Reporting Information [Line Items]
Loss associated with impairment of AmeriGas Propane goodwill			0
Corporate & Other
Segment Reporting Information [Line Items]
Loss on extinguishment of debt			(9,000,000)	(11,000,000)
Corporate & Other | AmeriGas Propane
Segment Reporting Information [Line Items]
Loss on extinguishment of debt			(9,000,000)	0
Loss associated with impairment of AmeriGas Propane goodwill			(656,000,000)
Corporate & Other | AmeriGas Propane | Revenues
Segment Reporting Information [Line Items]
Net gains (losses) on commodity derivative instruments not associated with current-period transactions			0	0	$ 0
Corporate & Other | AmeriGas Propane | Cost of sales
Segment Reporting Information [Line Items]
Net gains (losses) on commodity derivative instruments not associated with current-period transactions			(16,000,000)	(185,000,000)	167,000,000
Corporate & Other | 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
Corporate & Other | AmeriGas Propane | Operating and administrative expenses
Segment Reporting Information [Line Items]
AmeriGas performance enhancement			(24,000,000)	(5,000,000)
Restructuring costs				(16,000,000)	(54,000,000)
Impairment of customer relationship intangible					0
Costs associated with exit of the UGI International energy marketing business				0
Corporate & Other | 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
Corporate & Other | AmeriGas Propane | Income (loss) from equity investees
Segment Reporting Information [Line Items]
Impairments associated with certain equity method investments				0	0
Corporate & Other | AmeriGas Propane | Revenues/Operating and administrative expenses
Segment Reporting Information [Line Items]
Costs associated with exit of the UGI International energy marketing business			0
Corporate & Other | 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
Corporate & Other | UGI International
Segment Reporting Information [Line Items]
Loss on extinguishment of debt			0	(11,000,000)
Loss associated with impairment of AmeriGas Propane goodwill			0
Corporate & Other | UGI International | Revenues
Segment Reporting Information [Line Items]
Net gains (losses) on commodity derivative instruments not associated with current-period transactions			4,000,000	9,000,000	0
Corporate & Other | UGI International | Cost of sales
Segment Reporting Information [Line Items]
Net gains (losses) on commodity derivative instruments not associated with current-period transactions			(1,402,000,000)	797,000,000	1,065,000,000
Corporate & Other | UGI International | Other operating income, net
Segment Reporting Information [Line Items]
Net gains (losses) on commodity derivative instruments not associated with current-period transactions				2,000,000
Corporate & Other | UGI International | Operating and administrative expenses
Segment Reporting Information [Line Items]
AmeriGas performance enhancement			0	0
Restructuring costs				(9,000,000)	(33,000,000)
Impairment of customer relationship intangible					(20,000,000)
Costs associated with exit of the UGI International energy marketing business				(5,000,000)
Corporate & Other | 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			(38,000,000)	50,000,000	8,000,000
Corporate & Other | UGI International | Income (loss) from equity investees
Segment Reporting Information [Line Items]
Impairments associated with certain equity method investments				0	0
Corporate & Other | UGI International | Revenues/Operating and administrative expenses
Segment Reporting Information [Line Items]
Costs associated with exit of the UGI International energy marketing business			(27,000,000)
Corporate & Other | 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			(221,000,000)
Corporate & Other | Midstream & Marketing
Segment Reporting Information [Line Items]
Loss on extinguishment of debt			0	0
Loss associated with impairment of AmeriGas Propane goodwill			0
Corporate & Other | Midstream & Marketing | Revenues
Segment Reporting Information [Line Items]
Net gains (losses) on commodity derivative instruments not associated with current-period transactions			6,000,000	(4,000,000)	(15,000,000)
Corporate & Other | Midstream & Marketing | Cost of sales
Segment Reporting Information [Line Items]
Net gains (losses) on commodity derivative instruments not associated with current-period transactions			(236,000,000)	(21,000,000)	173,000,000
Corporate & Other | 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
Corporate & Other | Midstream & Marketing | Operating and administrative expenses
Segment Reporting Information [Line Items]
AmeriGas performance enhancement			0	0
Restructuring costs				(1,000,000)	0
Impairment of customer relationship intangible					0
Costs associated with exit of the UGI International energy marketing business				0
Corporate & Other | 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
Corporate & Other | Midstream & Marketing | Income (loss) from equity investees
Segment Reporting Information [Line Items]
Impairments associated with certain equity method investments				$ (35,000,000)	$ (93,000,000)
Corporate & Other | Midstream & Marketing | Revenues/Operating and administrative expenses
Segment Reporting Information [Line Items]
Costs associated with exit of the UGI International energy marketing business			0
Corporate & Other | 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