DERIVATIVE FINANCIAL INSTRUMENTS (Details Textuals) - USD ($)
$ in Millions |
3 Months Ended |
9 Months Ended |
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Sep. 30, 2016 |
Sep. 30, 2015 |
Sep. 30, 2016 |
Sep. 30, 2015 |
Jun. 30, 2016 |
Dec. 31, 2015 |
Jun. 30, 2012 |
Oct. 31, 2011 |
Dec. 22, 1997 |
| Derivative [Line Items] |
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| Gain (Loss) on Cash Flow Hedge Ineffectiveness, Net |
$ 0.0
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$ 0.0
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$ 0.0
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$ 0.0
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| Cash Collateral Provided By Us To Counterparties |
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$ 5.6
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| Cash flow hedges [Abstract] |
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| Commodity forward contracts with Wells Fargo |
43.8
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43.8
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| Commodity forward contracts with Citibank |
22.2
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22.2
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| Commodity Forward Contracts with Counterparty Merrill Lynch |
18.7
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18.7
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| Commodity Forward Contracts with Counterparty JPMorgan Chase |
16.6
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16.6
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| Fair value hedges [Abstract] |
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| Amount of terminated interest rate swaps |
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$ 73.1
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| Gain on terminated interest rate swaps |
0.2
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0.2
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$ 2.2
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| Series O Face Amount |
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$ 97.5
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| Series G Face Amount |
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$ 97.5
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| Interest Rate on SunBelt Notes |
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7.23%
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| Forward Contracts |
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| Derivative [Line Items] |
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| Notional amount |
89.5
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0.0
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89.5
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0.0
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21.7
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| Forward Contracts Sell |
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| Derivative [Line Items] |
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| Notional amount |
110.7
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0.0
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110.7
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0.0
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10.1
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| Variable Interest Rate Swaps $125M |
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| Derivative [Line Items] |
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| Notional amount |
125.0
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125.0
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| Deferred gain recognized |
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$ 11.0
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| Fixed Interest Rate Swaps $125M |
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| Derivative [Line Items] |
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| Notional amount |
125.0
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125.0
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| Fixed Interest Rate Swaps $1,100M (Tranche 1) [Member] |
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| Derivative [Line Items] |
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| Notional amount |
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$ 1,100.0
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| Fixed Interest Rate Swaps $900M (Tranche 2) [Member] |
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| Derivative [Line Items] |
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| Notional amount |
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900.0
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| Fixed Interest Rate Swaps $400M (Tranche 3) [Member] |
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| Derivative [Line Items] |
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| Notional amount |
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400.0
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| Interest Rate Swaps Designated As Fair Value Hedges |
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| Derivative [Line Items] |
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| Notional amount |
250.0
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$ 0.0
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250.0
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$ 0.0
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$ 250.0
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$ 0.0
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| Commodity Contract |
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| Derivative [Line Items] |
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| Cash Flow Hedge Gain (Loss) to be Reclassified wihtin Twelve Months |
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1.7
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| Cash Flow Hedges Derivative Instruments at Fair Value, Net |
2.9
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2.9
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| Interest Rate Contract |
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| Derivative [Line Items] |
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| Cash Flow Hedge Gain (Loss) to be Reclassified wihtin Twelve Months |
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0.3
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| Cash Flow Hedges Derivative Instruments at Fair Value, Net |
$ 2.3
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$ 2.3
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