RISK MANAGEMENT ACTIVITIES (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Derivative assets and liabilities from risk management activities
Risk Management Assets	$ 1.8	$ 3.9
Risk Management Liabilities	4.9	9.7
Non-hedge derivatives
Derivative assets and liabilities from risk management activities
Other current assets from risk management activities	1.8	1.7
Other long-term assets from risk management activities		2.2
Other current liabilities from risk management activities	2.9	5.4
Other long-term liabilities from risk management activities	2.0	4.3
Risk Management Assets	1.8	3.9
Risk Management Liabilities	4.9	9.7
Non-hedge derivatives | Commodity Contract
Derivative assets and liabilities from risk management activities
Derivatives designated as hedges for accounting purposes	0
Non-hedge derivatives | Natural gas contracts
Derivative assets and liabilities from risk management activities
Other current assets from risk management activities	0.9	0.1
Other current liabilities from risk management activities		0.6
Non-hedge derivatives | FTRs
Derivative assets and liabilities from risk management activities
Other current assets from risk management activities	0.7	1.2
Other current liabilities from risk management activities	0.1	0.1
Non-hedge derivatives | Petroleum product contracts
Derivative assets and liabilities from risk management activities
Other current assets from risk management activities	0.1	0.1
Non-hedge derivatives | Coal contract
Derivative assets and liabilities from risk management activities
Other current assets from risk management activities	0.1	0.3
Other long-term assets from risk management activities		2.2
Other current liabilities from risk management activities	2.8	4.7
Other long-term liabilities from risk management activities	$ 2.0	$ 4.3