RISK MANAGEMENT ACTIVITIES (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Derivative assets and liabilities from risk management activities
Risk Management Asset	$ 2.9	$ 3.9
Risk Management Liability	3.3	9.7
Non-hedge derivatives
Derivative assets and liabilities from risk management activities
Other current assets from risk management activities	2.9	1.7
Other long-term assets from risk management activities	0	2.2
Other current liabilities from risk management activities	3.0	5.4
Other long-term liabilities from risk management activities	0.3	4.3
Risk Management Asset	2.9	3.9
Risk Management Liability	3.3	9.7
Non-hedge derivatives | Natural gas 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	0.3	0.6
Non-hedge derivatives | FTRs
Derivative assets and liabilities from risk management activities
Other current assets from risk management activities	2.7	1.2
Other current liabilities from risk management activities	0.6	0.1
Non-hedge derivatives | Petroleum product contracts
Derivative assets and liabilities from risk management activities
Other current assets from risk management activities	0	0.1
Other current liabilities from risk management activities	0.1	0
Non-hedge derivatives | Coal contract
Derivative assets and liabilities from risk management activities
Other current assets from risk management activities	0	0.3
Other long-term assets from risk management activities	0	2.2
Other current liabilities from risk management activities	2.0	4.7
Other long-term liabilities from risk management activities	$ 0.3	$ 4.3
Designated as Hedging Instrument [Member] | Commodity Contract [Member]
Derivative assets and liabilities from risk management activities
Derivative, Number of Instruments Held	0