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DEBT AND CREDIT FACILITIES DEBT AND CREDIT FACILITIES (Debt Restructuring) (Details) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2016 | Sep. 30, 2016 | Mar. 31, 2016 | Mar. 31, 2015 | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014
Extinguishment of Debt [Line Items] |  |  |  |  |  |  |
Debt Instrument, Face Amount Exchanged |  |  | $ 512.2 | $ 674.6 |  |  |
Gain on extinguishment/restructuring of debt |  |  |  |  | $ 166.3 | $ 392.9 | $ 16.2
$544.2 Million 7.75% 2020 Second Lien Notes [Member] |  |  |  |  |  |  |
Extinguishment of Debt [Line Items] |  |  |  |  |  |  |
Debt Instrument, Face Amount Exchanged |  |  | 114.1 |  |  |  |
Debt Instrument, Face Amount Received in Debt Exchange of $400M 5.90% Notes |  |  |  | 57.5 |  |  |
Debt Instrument, Face Amount Received in Debt Exchange of $500M 4.80% Notes |  |  |  | 112.9 |  |  |
Debt instrument, Face Amount Received in Debt Exchange of $700M 4.875% Notes |  |  |  | 170.3 |  |  |
Debt Instrument, Face Amount Received in Debt Exchange of $800M 6.25% Notes |  |  |  | 203.5 |  |  |
Debt Instrument, Carrying Amount Received in Debt Exchange of $400M 5.90% Notes |  |  |  | 42.0 |  |  |
Debt Instrument, Carrying Value Received in Debt Exchange of $500M 4.80% Notes |  |  |  | 82.4 |  |  |
Debt instrument, Carrying Value Received in Debt Exchange of $700M 4.875% Notes |  |  |  | 124.3 |  |  |
Debt Instrument, Carrying Value Received in Debt Exchange of $800M 6.25% Notes |  |  |  | 148.5 |  |  |
Debt Instrument, Par Value | $ 430.1 |  |  | 544.2 | 430.1 | 544.2 |
Debt, carrying value |  |  |  | 397.2 |  |  |
$544.2 Million 7.75% 2020 Second Lien Notes [Member] | Exchange of Debt [Member] |  |  |  |  |  |  |
Extinguishment of Debt [Line Items] |  |  |  |  |  |  |
Gain on extinguishment/restructuring of debt |  |  | 6.9 |  |  | 269.5 |
Five Hundred Million Three Point Nine Five Two Thousand Eighteen Senior Note [Member] |  |  |  |  |  |  |
Extinguishment of Debt [Line Items] |  |  |  |  |  |  |
Debt Instrument, Face Amount Exchanged |  |  | 17.6 |  |  |  |
Gain on extinguishment/restructuring of debt |  | $ (19.9) |  |  |  |  |
Debt Instrument, Par Value |  |  |  |  |  | 311.2 |
Five Hundred Million Three Point Nine Five Two Thousand Eighteen Senior Note [Member] | Exchange of Debt [Member] |  |  |  |  |  |  |
Extinguishment of Debt [Line Items] |  |  |  |  |  |  |
Gain on extinguishment/restructuring of debt |  |  | 1.8 |  |  |  |
Four Hundred Million Five Point Nine Zero Two Thousand And Twenty Senior Note [Member] |  |  |  |  |  |  |
Extinguishment of Debt [Line Items] |  |  |  |  |  |  |
Debt Instrument, Face Amount Exchanged |  |  | 65.1 | 67.0 |  |  |
Debt Instrument, Par Value | 225.6 |  |  |  | 225.6 | 290.8 |
Four Hundred Million Five Point Nine Zero Two Thousand And Twenty Senior Note [Member] | Exchange of Debt [Member] |  |  |  |  |  |  |
Extinguishment of Debt [Line Items] |  |  |  |  |  |  |
Gain on extinguishment/restructuring of debt |  |  | 28.3 | 24.5 |  |  |
$500 Million 4.80% 2020 Senior Notes[Member] |  |  |  |  |  |  |
Extinguishment of Debt [Line Items] |  |  |  |  |  |  |
Debt Instrument, Face Amount Exchanged |  |  | 44.7 | 137.8 |  |  |
Gain on extinguishment/restructuring of debt | 0.6 |  |  |  |  |  |
Debt Instrument, Par Value | 236.8 |  |  |  | 236.8 | 306.7 |
$500 Million 4.80% 2020 Senior Notes[Member] | Exchange of Debt [Member] |  |  |  |  |  |  |
Extinguishment of Debt [Line Items] |  |  |  |  |  |  |
Gain on extinguishment/restructuring of debt |  |  | 19.5 | 54.6 |  |  |
$700 Million 4.875% 2021 Senior Notes[Member] |  |  |  |  |  |  |
Extinguishment of Debt [Line Items] |  |  |  |  |  |  |
Debt Instrument, Face Amount Exchanged |  |  | 76.3 | 208.5 |  |  |
Debt Instrument, Par Value | 309.4 |  |  |  | 309.4 | 412.5 |
$700 Million 4.875% 2021 Senior Notes[Member] | Exchange of Debt [Member] |  |  |  |  |  |  |
Extinguishment of Debt [Line Items] |  |  |  |  |  |  |
Gain on extinguishment/restructuring of debt |  |  | 33.3 | 83.1 |  |  |
$800 Million 6.25% 2040 Senior Notes [Member] |  |  |  |  |  |  |
Extinguishment of Debt [Line Items] |  |  |  |  |  |  |
Debt Instrument, Face Amount Exchanged |  |  | 194.4 | 261.3 |  |  |
Debt Instrument, Par Value | 298.4 |  |  |  | 298.4 | $ 492.8 |
$800 Million 6.25% 2040 Senior Notes [Member] | Exchange of Debt [Member] |  |  |  |  |  |  |
Extinguishment of Debt [Line Items] |  |  |  |  |  |  |
Gain on extinguishment/restructuring of debt |  |  | 84.5 | $ 107.3 |  |  |
$218.5 Million 8.00% 2020 1.5 Lien Notes [Member] |  |  |  |  |  |  |
Extinguishment of Debt [Line Items] |  |  |  |  |  |  |
Debt Instrument, Face Amount Received in Debt Exchange of $544M 7.75% Notes |  |  | 57.0 |  |  |  |
Debt Instrument, Face Amount Received in Debt Exchange of $500M 3.95% Notes |  |  | 11.4 |  |  |  |
Debt Instrument, Face Amount Received in Debt Exchange of $400M 5.90% Notes |  |  | 26.0 |  |  |  |
Debt Instrument, Face Amount Received in Debt Exchange of $500M 4.80% Notes |  |  | 17.9 |  |  |  |
Debt instrument, Face Amount Received in Debt Exchange of $700M 4.875% Notes |  |  | 30.5 |  |  |  |
Debt Instrument, Face Amount Received in Debt Exchange of $800M 6.25% Notes |  |  | 75.7 |  |  |  |
Debt Instrument, Carrying Amount Received in Debt Exchange of $544.2M 7.75% Notes |  |  | 77.5 |  |  |  |
Debt Instrument, Carrying Amount Received in Debt Exchange of $500M 3.95% Notes |  |  | 15.5 |  |  |  |
Debt Instrument, Carrying Amount Received in Debt Exchange of $400M 5.90% Notes |  |  | 35.4 |  |  |  |
Debt Instrument, Carrying Value Received in Debt Exchange of $500M 4.80% Notes |  |  | 24.4 |  |  |  |
Debt instrument, Carrying Value Received in Debt Exchange of $700M 4.875% Notes |  |  | 41.5 |  |  |  |
Debt Instrument, Carrying Value Received in Debt Exchange of $800M 6.25% Notes |  |  | 103.0 |  |  |  |
Debt Instrument, Par Value | $ 218.5 |  | 218.5 |  | 218.5 |  |
Debt, carrying value |  |  | $ 297.3 |  |  |  |
$218.5 Million 8.00% 2020 1.5 Lien Notes [Member] | Exchange of Debt [Member] |  |  |  |  |  |  |
Extinguishment of Debt [Line Items] |  |  |  |  |  |  |
Gain on extinguishment/restructuring of debt |  |  |  |  | $ 174.3 |  |

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