DERIVATIVE FINANCIAL INSTRUMENTS AND HEDGING ACTIVITIES (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
DERIVATIVE FINANCIAL INSTRUMENTS AND HEDGING ACTIVITIES [Abstract]
Unrecognized gains (losses) of derivative financial instruments that were classified as cash flow hedges			$ (23.9)		$ (28.4)
De-designated unrealized commodity hedge gains (losses)			1.5	$ (0.2)
Cash flow hedge gain (loss) to be reclassified within twelve months			(316.5)
Net asset (liability) position	$ (374.0)		(374.0)		(160.9)
Expected value of cash collateral or letters of credit if credit rating is downgraded	83.5		83.5
Letters of credit outstanding, derivatives	417.7		417.7		$ 329.6
Short Term Debt Hedging Instruments [Member]
Derivative [Line Items]
Realized gain (loss) on termination of interest rate hedge				$ (0.8)
Forward Starting Interest Rate Swaps Entered Into [Member]
Derivative [Line Items]
Term of derivatives				10 years
Notional amount		$ 2,350.0		$ 2,350.0
Amended Interest Rate Hedges [Member]
Derivative [Line Items]
Unrealized gains (losses) on interest rate hedge ineffectiveness	$ 7.9	$ 62.2	$ 22.0	$ 62.2