Utility Regulatory Assets and Liabilities and Regulatory Matters - Regulatory Assets and Liabilities Associated with Gas Utility and Electric Utility (Details) - UGI Utilities - USD ($) $ in Millions	Jun. 30, 2018	Sep. 30, 2017	Jun. 30, 2017
Regulatory Assets
Regulatory assets	$ 360.1	$ 368.9	$ 398.8
Regulatory Liabilities
Regulatory liabilities	412.5	49.2	48.7
Postretirement benefits
Regulatory Liabilities
Regulatory liabilities	16.9	17.5	16.7
Deferred fuel and power refunds
Regulatory Liabilities
Regulatory liabilities	44.5	10.6	12.6
State tax benefits — distribution system repairs
Regulatory Liabilities
Regulatory liabilities	20.7	18.4	16.7
PUC Temporary Rates Order
Regulatory Liabilities
Regulatory liabilities	24.1	0.0	0.0
Excess federal deferred income taxes
Regulatory Liabilities
Regulatory liabilities	301.2	0.0	0.0
Other
Regulatory Liabilities
Regulatory liabilities	5.1	2.7	2.7
Income taxes recoverable
Regulatory Assets
Regulatory assets	130.0	121.4	122.7
Underfunded pension and postretirement plans
Regulatory Assets
Regulatory assets	132.2	141.3	171.8
Environmental costs
Regulatory Assets
Regulatory assets	59.8	61.6	61.6
Deferred fuel and power costs
Regulatory Assets
Regulatory assets	0.2	7.7	7.0
Removal costs, net
Regulatory Assets
Regulatory assets	31.0	31.0	29.4
Other
Regulatory Assets
Regulatory assets	$ 6.9	$ 5.9	$ 6.3