Utility Regulatory Assets and Liabilities and Regulatory Matters - Regulatory Assets and Liabilities Associated with Gas Utility and Electric Utility (Details) - USD ($) $ in Millions		Mar. 31, 2016	Sep. 30, 2015	Mar. 31, 2015
Regulatory Assets And Liabilities
Regulatory assets		$ 348.2	$ 304.2	$ 252.6
Regulatory liabilities	[1]	66.8	71.0	72.6
Postretirement benefits
Regulatory Assets And Liabilities
Regulatory liabilities	[1]	19.3	20.0	19.3
Deferred fuel and power refunds
Regulatory Assets And Liabilities
Regulatory liabilities	[1]	30.8	36.6	40.6
State tax benefits—distribution system repairs
Regulatory Assets And Liabilities
Regulatory liabilities	[1]	14.2	13.3	10.6
Other
Regulatory Assets And Liabilities
Regulatory liabilities	[1]	2.5	1.1	2.1
Income taxes recoverable
Regulatory Assets And Liabilities
Regulatory assets		118.2	115.9	111.5
Underfunded pension and postretirement plans
Regulatory Assets And Liabilities
Regulatory assets		135.8	140.8	105.5
Environmental costs
Regulatory Assets And Liabilities
Regulatory assets	[2]	60.5	20.0	14.1
Removal costs, net
Regulatory Assets And Liabilities
Regulatory assets		25.0	21.2	18.4
Other
Regulatory Assets And Liabilities
Regulatory assets		$ 8.7	$ 6.3	$ 3.1

[1] Regulatory liabilities are recorded in other current and other noncurrent liabilities on the Condensed Consolidated Balance Sheets.

[2] Environmental costs at March 31, 2016, include amounts probable of recovery recorded in conjunction with UGI Gas’ Consent Order and Agreement with the Pennsylvania Department of Environmental Protection (see Note 9).