Commitments and Contingencies (Details) $ in Millions	9 Months Ended	12 Months Ended
	Jun. 30, 2020 USD ($) agreement subsidiary	Dec. 31, 2017 record_of_decision	Dec. 31, 2008 lb	Dec. 31, 2007 lb	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Sep. 30, 2017 USD ($)
Loss Contingencies
Environmental expenditures cap during calendar year	$ 5.4
Number of COAs | agreement	3
Amount of propane in cylinders before reduction (in pounds) | lb				17
Amount of propane in cylinders after reduction (in pounds) | lb			15
CPG, PNG and UGI Gas COAs
Loss Contingencies
Accrual for environmental loss contingencies	$ 55.3				$ 50.4	$ 47.6
UGI Utilities | PNG and CPG
Loss Contingencies
Number of subsidiaries acquired with similar histories | subsidiary	2
AmeriGas OLP | Saranac Lake, New York | New York State Department of Environment Conservation Remediation Plan
Loss Contingencies
Accrual for environmental loss contingencies	$ 7.5
Loss contingency, number of remediation plans | record_of_decision		3
Estimated remediation plan cost							$ 27.7