FAIR VALUE (Details 3) (USD $) In Millions, unless otherwise specified							12 Months Ended			12 Months Ended						12 Months Ended					12 Months Ended				12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013 Fair value measurements on a recurring basis Level 3	Dec. 31, 2012 Fair value measurements on a recurring basis Level 3	Dec. 31, 2013 Fair value measurements on a recurring basis Utility segments Level 3 FTRs	Dec. 31, 2012 Fair value measurements on a recurring basis Utility segments Level 3 FTRs	Dec. 31, 2013 Fair value measurements on a recurring basis Utility segments Level 3 FTRs Valuation Technique: Market-based Weighted Average	Dec. 31, 2013 Fair value measurements on a recurring basis Utility segments Level 3 Coal contracts	Dec. 31, 2012 Fair value measurements on a recurring basis Utility segments Level 3 Coal contracts	Dec. 31, 2013 Fair value measurements on a recurring basis Utility segments Level 3 Coal contracts Valuation Technique: Market-based Minimum	Dec. 31, 2013 Fair value measurements on a recurring basis Utility segments Level 3 Coal contracts Valuation Technique: Market-based Maximum	Dec. 31, 2013 Fair value measurements on a recurring basis Utility segments Level 3 Natural gas contracts	Dec. 31, 2012 Fair value measurements on a recurring basis Utility segments Level 3 Natural gas contracts	Dec. 31, 2013 Fair value measurements on a recurring basis Nonregulated segments Level 3	Dec. 31, 2013 Fair value measurements on a recurring basis Nonregulated segments Level 3 Maximum	Dec. 31, 2013 Fair value measurements on a recurring basis Nonregulated segments Level 3 Valuation Technique: Market-based	Dec. 31, 2013 Fair value measurements on a recurring basis Nonregulated segments Level 3 Contingent consideration Valuation Technique: Income-based Minimum	Dec. 31, 2013 Fair value measurements on a recurring basis Nonregulated segments Level 3 Contingent consideration Valuation Technique: Income-based Maximum	Dec. 31, 2013 Fair value measurements on a recurring basis Nonregulated segments Level 3 Natural gas contracts	Dec. 31, 2012 Fair value measurements on a recurring basis Nonregulated segments Level 3 Natural gas contracts	Dec. 31, 2013 Fair value measurements on a recurring basis Nonregulated segments Level 3 Natural gas contracts Valuation Technique: Market-based Minimum	Dec. 31, 2013 Fair value measurements on a recurring basis Nonregulated segments Level 3 Natural gas contracts Valuation Technique: Market-based Maximum	Dec. 31, 2013 Fair value measurements on a recurring basis Nonregulated segments Level 3 Electric contracts	Dec. 31, 2012 Fair value measurements on a recurring basis Nonregulated segments Level 3 Electric contracts	Dec. 31, 2013 Fair value measurements on a recurring basis Nonregulated segments Level 3 Electric contracts Valuation Technique: Market-based	Dec. 31, 2013 Fair value measurements on a recurring basis Nonregulated segments Level 3 Electric contracts Valuation Technique: Market-based Minimum	Dec. 31, 2013 Fair value measurements on a recurring basis Nonregulated segments Level 3 Electric contracts Valuation Technique: Market-based Maximum
Fair Value Inputs, Assets and Liabilities, Quantitative Information
Risk Management Assets	$ 315.5	$ 190.7	$ 53.8	$ 19.6	$ 2.1	$ 2.1		$ 0.2	$ 2.5			$ 0	$ 0						$ 35.6	$ 5.4			$ 15.9	$ 9.6
Risk Management Liabilities	226.6	240.3	31.7	24.5	0.3	0.1		2.7	9.0			0	0						25.2	1.5			3.5	13.9
Contingent Consideration														$ 7.8	$ 8.0
Fair Value Inputs
Forward market prices (in dollars per megawatt-month, ton, dekatherm, or megawatt-hours)							174.52			11.73	14.30										(1.53)	17.30				(3.30)	9.25
Probability of default (as a percent)																					11.60%	51.00%			26.00%
Counterparty default time period (in years)																1 year
Option volatilities (as a percent)																										14.80%	199.90%
Monthly curve shaping (as a percent)																									(33.30%)
Growth rate (as a percent)																	(13.20%)	49.30%