DERIVATIVE FINANCIAL INSTRUMENTS (Details Textuals) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014	Jun. 30, 2012	Oct. 31, 2011	Dec. 22, 1997
Cash flow hedges [Abstract]
Commodity forward contracts with Wells Fargo	$ 49.8		$ 49.8
Commodity forward contracts with Citibank	21.0		21.0
Cash Flow Hedges Derivative Instruments at Fair Value, Net	11.4		11.4
Cash Flow Hedge Gain (Loss) to be Reclassified wihtin Twelve Months			5.1
Fair value hedges [Abstract]
Amount of terminated interest rate swaps						$ 73.1
Gain on terminated interest rate swaps	0.5		0.5			$ 2.2
Series O Face Amount								$ 97.5
Series G Face Amount								$ 97.5
Interest Rate on SunBelt Notes								7.23%
Gain (Loss) on Cash Flow Hedge Ineffectiveness, Net	0.0	$ 0.0	0.0	$ 0.0
CashCollateralProvidedByUsToCounterparties	3.8		3.8
Variable Interest Rate Swaps $125M
Derivative [Line Items]
Notional amount	125.0		125.0
Amount of gain included in long-term debt	1.9		1.9				$ 11.0
Fixed Interest Rate Swaps $125M
Derivative [Line Items]
Notional amount	125.0		125.0
Interest Rate Swaps Designated As Fair Value Hedges
Derivative [Line Items]
Notional amount	$ 0.0	$ 0.0	$ 0.0	$ 0.0	$ 0.0