Commitments and Contingencies - Contingencies (Details) $ in Millions	1 Months Ended	6 Months Ended	12 Months Ended
	Mar. 31, 2017 USD ($) record_of_decision	Oct. 31, 2014 lawsuit	Sep. 30, 2017 USD ($) subsidiary lb	Sep. 30, 2016 USD ($)
Loss Contingencies [Line Items]
Class action lawsuits (more than) | lawsuit		35
Amount of propane in cylinders being sold | lb			17
Reduced amount of propane in cylinders being sold | lb			15
UGI Utilities | Environmental Issue
Loss Contingencies [Line Items]
Environmental expenditures cap during calendar year			$ 2.5
CPG MPG | Environmental Issue
Loss Contingencies [Line Items]
Environmental expenditures cap during calendar year			1.8
PNG MPG | Environmental Issue
Loss Contingencies [Line Items]
Environmental expenditures cap during calendar year			1.1
CPG, PNG and UGI Gas COAs
Loss Contingencies [Line Items]
Accrued liabilities for environmental investigation and remediation costs related to CPG-COA and PNG-COA			$ 54.3	$ 55.1
UGI Utilities | CPG and PNG
Loss Contingencies [Line Items]
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 [Line Items]
Accrued liabilities for environmental investigation and remediation costs related to CPG-COA and PNG-COA			$ 7.5
Number of records of decisions drafted | record_of_decision	3
Estimated remediation plan cost	$ 27.7