RISK MANAGEMENT ACTIVITIES - RISK MANAGEMENT ASSETS AND LIABILITIES (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Derivative assets and liabilities from risk management activities
Risk Management Asset	$ 8.2	$ 2.4
Risk Management Liability	2.7	3.1
Designated as hedging instrument
Derivative assets and liabilities from risk management activities
Number of derivative instruments held	0
Non-hedge derivatives
Derivative assets and liabilities from risk management activities
Other current assets from risk management activities	5.5	2.2
Other long-term assets from risk management activities	2.7	0.2
Risk Management Asset	8.2	2.4
Other current liabilities from risk management activities	2.5	2.3
Other long-term liabilities from risk management activities	0.2	0.8
Risk Management Liability	2.7	3.1
Non-hedge derivatives | Natural gas contracts
Derivative assets and liabilities from risk management activities
Other current assets from risk management activities	0.6	0.6
Other current liabilities from risk management activities	0.2	0.1
Non-hedge derivatives | FTRs
Derivative assets and liabilities from risk management activities
Other current assets from risk management activities	4.7	1.5
Other current liabilities from risk management activities	0.7	0.3
Non-hedge derivatives | Petroleum product contracts
Derivative assets and liabilities from risk management activities
Other current assets from risk management activities	0.2	0.1
Other current liabilities from risk management activities	0	0
Non-hedge derivatives | Coal contracts
Derivative assets and liabilities from risk management activities
Other current assets from risk management activities	0	0
Other long-term assets from risk management activities	2.7	0.2
Other current liabilities from risk management activities	1.6	1.9
Other long-term liabilities from risk management activities	$ 0.2	$ 0.8