RISK MANAGEMENT ACTIVITIES (Details 3) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Natural gas contracts | Balance Sheet - Regulatory assets (current)
Risk management activities
Unrealized gain (loss) related to non-hedge derivative contracts	$ 0.7	$ 2.2	$ (0.1)
Natural gas contracts | Balance Sheet - Regulatory liabilities (current)
Risk management activities
Unrealized gain (loss) related to non-hedge derivative contracts	0.3	0.1	(0.2)
Natural gas contracts | Income Statement - Cost of fuel, natural gas and purchased power
Risk management activities
Unrealized gain (loss) related to non-hedge derivative contracts	0	0.2	0
FTRs | Balance Sheet - Regulatory assets (current)
Risk management activities
Unrealized gain (loss) related to non-hedge derivative contracts	0.2	(0.1)	(0.1)
FTRs | Balance Sheet - Regulatory liabilities (current)
Risk management activities
Unrealized gain (loss) related to non-hedge derivative contracts	(0.3)	0	(1.1)
Petroleum product contracts | Balance Sheet - Regulatory assets (current)
Risk management activities
Unrealized gain (loss) related to non-hedge derivative contracts	0	0.1	(0.1)
Petroleum product contracts | Balance Sheet - Regulatory liabilities (current)
Risk management activities
Unrealized gain (loss) related to non-hedge derivative contracts	0.1	0	0
Petroleum product contracts | Income Statement - Operating and maintenance expense
Risk management activities
Unrealized gain (loss) related to non-hedge derivative contracts	0	0	(0.1)
Coal contract | Balance Sheet - Regulatory assets (current)
Risk management activities
Unrealized gain (loss) related to non-hedge derivative contracts	(0.9)	(2.2)	(1.3)
Coal contract | Balance Sheet - Regulatory assets (long Term)
Risk management activities
Unrealized gain (loss) related to non-hedge derivative contracts	3.5	0.1	(4.4)
Coal contract | Balance Sheet - Regulatory liabilities (current)
Risk management activities
Unrealized gain (loss) related to non-hedge derivative contracts	(0.2)	0.3	0
Coal contract | Balance Sheet - Regulatory liabilities (long-term)
Risk management activities
Unrealized gain (loss) related to non-hedge derivative contracts	$ (2.0)	$ 2.2	$ (3.7)