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, 2017	Sep. 30, 2017	Dec. 31, 2016
Regulatory Assets
Regulatory assets	$ 362.8	$ 368.9	$ 392.9
Regulatory Liabilities
Regulatory liabilities	357.5	49.2	58.7
Postretirement benefits
Regulatory Liabilities
Regulatory liabilities	17.3	17.5	17.3
Deferred fuel and power refunds
Regulatory Liabilities
Regulatory liabilities	12.7	10.6	23.8
State tax benefits — distribution system repairs
Regulatory Liabilities
Regulatory liabilities	19.1	18.4	15.6
Excess federal deferred income taxes
Regulatory Liabilities
Regulatory liabilities	303.9	0.0	0.0
Other
Regulatory Liabilities
Regulatory liabilities	4.5	2.7	2.0
Income taxes recoverable
Regulatory Assets
Regulatory assets	126.5	121.4	117.8
Underfunded pension and postretirement plans
Regulatory Assets
Regulatory assets	138.3	141.3	179.4
Environmental costs
Regulatory Assets
Regulatory assets	60.8	61.6	61.4
Deferred fuel and power costs
Regulatory Assets
Regulatory assets	0.1	7.7	0.0
Removal costs, net
Regulatory Assets
Regulatory assets	31.4	31.0	27.1
Other
Regulatory Assets
Regulatory assets	$ 5.7	$ 5.9	$ 7.2