RISK MANAGEMENT ACTIVITIES (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Derivative assets and liabilities from risk management activities
Current assets from risk management activities	$ 240.1	$ 145.4
Long-term assets from risk management activities	75.4	45.3
Risk Management Assets	315.5	190.7
Current liabilities from risk management activities	163.8	181.9
Long-term liabilities from risk management activities	62.8	58.4
Risk Management Liabilities	226.6	240.3
Non-hedge derivatives | Utility segments | Natural gas contracts
Derivative assets and liabilities from risk management activities
Current assets from risk management activities	8.3	2.5
Long-term assets from risk management activities	1.8	0.9
Current liabilities from risk management activities	1.0	14.0
Long-term liabilities from risk management activities	0.1	0.8
Non-hedge derivatives | Utility segments | FTRs
Derivative assets and liabilities from risk management activities
Current assets from risk management activities	2.1	2.1
Current liabilities from risk management activities	0.3	0.1
Non-hedge derivatives | Utility segments | Petroleum product contracts
Derivative assets and liabilities from risk management activities
Current assets from risk management activities	0.1	0.2
Current liabilities from risk management activities	0	0
Non-hedge derivatives | Utility segments | Coal contracts
Derivative assets and liabilities from risk management activities
Current assets from risk management activities	0	0.3
Long-term assets from risk management activities	0.2	2.2
Current liabilities from risk management activities	1.9	4.7
Long-term liabilities from risk management activities	0.8	4.3
Non-hedge derivatives | Nonregulated segments | Natural gas contracts
Derivative assets and liabilities from risk management activities
Current assets from risk management activities	57.6	51.7
Long-term assets from risk management activities	29.5	11.5
Current liabilities from risk management activities	42.9	48.5
Long-term liabilities from risk management activities	18.6	7.6
Non-hedge derivatives | Nonregulated segments | Electric contracts
Derivative assets and liabilities from risk management activities
Current assets from risk management activities	172.0	88.6
Long-term assets from risk management activities	43.9	30.7
Current liabilities from risk management activities	117.7	114.2
Long-term liabilities from risk management activities	43.3	45.7
Cash flow hedges | Utility segments | Natural gas contracts
Derivative assets and liabilities from risk management activities
Current assets from risk management activities		0
Current liabilities from risk management activities		$ 0.4