Segment Information - Reconciliation of Partnership Adjusted EBITDA (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Segment Reporting Information [Line Items]
Net gains on commodity derivative instruments not associated with current-period transactions			$ 185	$ (155)
Operating Segments | AmeriGas Propane | Revenues
Segment Reporting Information [Line Items]
Net gains on commodity derivative instruments not associated with current-period transactions	$ 0	$ 0		0
Operating Segments | AmeriGas Propane | Cost of sales
Segment Reporting Information [Line Items]
Net gains on commodity derivative instruments not associated with current-period transactions	27	(21)	64	(12)
Operating Segments | AmeriGas Propane | Other non-operating income (expense), net
Segment Reporting Information [Line Items]
Net gains on commodity derivative instruments not associated with current-period transactions	0	0	0	0
Operating Segments | AmeriGas Propane | Operating and administrative expenses
Segment Reporting Information [Line Items]
Business transformation expenses	(14)	(13)	(26)	(24)
Operating Segments | AmeriGas Propane | Operating and administrative expenses | CMG Acquisition
Segment Reporting Information [Line Items]
Acquisition and integration expenses associated with the CMG Acquisition		0		0
Operating Segments | UGI International | Revenues
Segment Reporting Information [Line Items]
Net gains on commodity derivative instruments not associated with current-period transactions	0	0		0
Operating Segments | UGI International | Cost of sales
Segment Reporting Information [Line Items]
Net gains on commodity derivative instruments not associated with current-period transactions	48	(118)	154	(132)
Operating Segments | UGI International | Other non-operating income (expense), net
Segment Reporting Information [Line Items]
Net gains on commodity derivative instruments not associated with current-period transactions	15	2	(5)	(13)
Operating Segments | UGI International | Operating and administrative expenses
Segment Reporting Information [Line Items]
Business transformation expenses	(3)	(6)	(6)	(12)
Operating Segments | UGI International | Operating and administrative expenses | CMG Acquisition
Segment Reporting Information [Line Items]
Acquisition and integration expenses associated with the CMG Acquisition		0		0
Operating Segments | Midstream & Marketing | Revenues
Segment Reporting Information [Line Items]
Net gains on commodity derivative instruments not associated with current-period transactions	(2)	3		5
Operating Segments | Midstream & Marketing | Cost of sales
Segment Reporting Information [Line Items]
Net gains on commodity derivative instruments not associated with current-period transactions	1	6	(28)	(3)
Operating Segments | Midstream & Marketing | Other non-operating income (expense), net
Segment Reporting Information [Line Items]
Net gains on commodity derivative instruments not associated with current-period transactions	0	0	0	0
Operating Segments | Midstream & Marketing | Operating and administrative expenses
Segment Reporting Information [Line Items]
Business transformation expenses	$ 0	0	$ 0	0
Operating Segments | Midstream & Marketing | Operating and administrative expenses | CMG Acquisition
Segment Reporting Information [Line Items]
Acquisition and integration expenses associated with the CMG Acquisition		$ (1)		$ (2)