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	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
Regulatory Assets
Regulatory assets	$ 298.8	$ 301.0	$ 362.8
Regulatory Liabilities
Regulatory liabilities	373.5	390.2	357.5
Postretirement benefits
Regulatory Liabilities
Regulatory liabilities	17.3	17.8	17.3
Deferred fuel and power refunds
Regulatory Liabilities
Regulatory liabilities	22.2	36.7	12.7
State tax benefits — distribution system repairs
Regulatory Liabilities
Regulatory liabilities	23.5	22.6	19.1
PAPUC temporary rates order
Regulatory Liabilities
Regulatory liabilities	24.8	24.4	0.0
Excess federal deferred income taxes
Regulatory Liabilities
Regulatory liabilities	280.9	285.2	303.9
Other
Regulatory Liabilities
Regulatory liabilities	4.8	3.5	4.5
Income taxes recoverable
Regulatory Assets
Regulatory assets	115.2	110.1	126.5
Underfunded pension and postretirement plans
Regulatory Assets
Regulatory assets	85.3	87.1	138.3
Environmental costs
Regulatory Assets
Regulatory assets	58.5	58.8	60.8
Removal costs, net
Regulatory Assets
Regulatory assets	31.3	32.0	31.4
Other
Regulatory Assets
Regulatory assets	$ 8.5	$ 13.0	$ 5.8