Segment Information - Corporate and Other segment information (Details) - USD ($) $ in Millions	3 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Loss on extinguishments of debt	$ 0.0	$ (6.1)
Corporate & Other
Segment Reporting Information [Line Items]
Loss on extinguishments of debt		(6.1)
Corporate & Other \| AmeriGas Propane
Segment Reporting Information [Line Items]
LPG business transformation expenses	(11.2)
Loss on extinguishments of debt		0.0
Corporate & Other \| UGI International
Segment Reporting Information [Line Items]
LPG business transformation expenses	(5.5)
Loss on extinguishments of debt		(6.1)
Corporate & Other \| Midstream & Marketing
Segment Reporting Information [Line Items]
LPG business transformation expenses	0.0
Loss on extinguishments of debt		0.0
Commodity contracts \| Corporate & Other \| AmeriGas Propane
Segment Reporting Information [Line Items]
Net gains (losses) on commodity derivative instruments not associated with current-period transactions	9.4	(78.5)
Commodity contracts \| Corporate & Other \| UGI International
Segment Reporting Information [Line Items]
Net gains (losses) on commodity derivative instruments not associated with current-period transactions	(13.5)	(97.3)
Commodity contracts \| Corporate & Other \| Midstream & Marketing
Segment Reporting Information [Line Items]
Net gains (losses) on commodity derivative instruments not associated with current-period transactions	(7.5)	1.8
Forward foreign currency exchange contracts \| Corporate & Other \| AmeriGas Propane
Segment Reporting Information [Line Items]
Net gains (losses) on commodity derivative instruments not associated with current-period transactions	0.0	0.0
Forward foreign currency exchange contracts \| Corporate & Other \| UGI International
Segment Reporting Information [Line Items]
Net gains (losses) on commodity derivative instruments not associated with current-period transactions	(15.7)	8.1
Forward foreign currency exchange contracts \| Corporate & Other \| Midstream & Marketing
Segment Reporting Information [Line Items]
Net gains (losses) on commodity derivative instruments not associated with current-period transactions	0.0	$ 0.0
Affiliated Entity \| CMG \| Pennant \| Corporate & Other \| AmeriGas Propane
Segment Reporting Information [Line Items]
Acquisition and integration expenses associated with the CMG Acquisition	0.0
Affiliated Entity \| CMG \| Pennant \| Corporate & Other \| UGI International
Segment Reporting Information [Line Items]
Acquisition and integration expenses associated with the CMG Acquisition	0.0
Affiliated Entity \| CMG \| Pennant \| Corporate & Other \| Midstream & Marketing
Segment Reporting Information [Line Items]
Acquisition and integration expenses associated with the CMG Acquisition	$ (0.7)

This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

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