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	Mar. 31, 2018	Sep. 30, 2017	Mar. 31, 2017
Regulatory Assets
Regulatory assets	$ 361.6	$ 368.9	$ 394.7
Regulatory Liabilities
Regulatory liabilities	380.7	49.2	50.5
Postretirement benefits
Regulatory Liabilities
Regulatory liabilities	17.1	17.5	17.0
Deferred fuel and power refunds
Regulatory Liabilities
Regulatory liabilities	35.3	10.6	13.8
State tax benefits — distribution system repairs
Regulatory Liabilities
Regulatory liabilities	19.9	18.4	16.1
Excess federal deferred income taxes
Regulatory Liabilities
Regulatory liabilities	301.2	0.0	0.0
Other
Regulatory Liabilities
Regulatory liabilities	7.2	2.7	3.6
Income taxes recoverable
Regulatory Assets
Regulatory assets	128.3	121.4	120.3
Underfunded pension and postretirement plans
Regulatory Assets
Regulatory assets	135.3	141.3	175.6
Environmental costs
Regulatory Assets
Regulatory assets	59.8	61.6	62.2
Deferred fuel and power costs
Regulatory Assets
Regulatory assets	0.7	7.7	1.3
Removal costs, net
Regulatory Assets
Regulatory assets	30.5	31.0	28.8
Other
Regulatory Assets
Regulatory assets	$ 7.0	$ 5.9	$ 6.5