Commitments and Contingencies (Details) $ in Millions	9 Months Ended	12 Months Ended			20 Months Ended
	Jun. 30, 2019 USD ($) subsidiary	Dec. 31, 2017 record_of_decision	Dec. 31, 2008 lb	Dec. 31, 2007 lb	Jul. 01, 2019 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)
Loss Contingencies
Amount of propane in cylinders before reduction (in pounds) | lb				17
Amount of propane in cylinders after reduction (in pounds) | lb			15
UGI Gas | Environmental Matters
Loss Contingencies
Environmental expenditures cap during calendar year	$ 5.4
CPG, PNG and UGI Gas COAs
Loss Contingencies
Accrual for environmental loss contingencies	$ 47.6					$ 51.0	$ 52.2
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
Forecast
Loss Contingencies
Capital contributions					$ 225.0