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DEBT AND CREDIT FACILITIES (Debt Extinguishment) (Details) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2018 | Sep. 30, 2016 | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Extinguishment of Debt [Line Items] |  |  |  |  |
Debt Extinguished |  |  | $ 227.4 | $ 1,610.7 |
Gain (loss) on extinguishment of debt |  |  | (6.8) | (165.4) | $ 166.3
Debt redemption premiums paid |  | $ 17.4 | 7.1 | 110.0 |
$540 Million 8.25% 2020 First Lien Notes |  |  |  |  |
Extinguishment of Debt [Line Items] |  |  |  |  |
Debt Extinguished | $ 35.6 |  |  | 540.0 |
Gain (loss) on extinguishment of debt |  |  |  | (93.5) |
$218.5 Million 8.00% 2020 1.5 Lien Notes |  |  |  |  |
Extinguishment of Debt [Line Items] |  |  |  |  |
Debt Extinguished |  |  |  | 218.5 |
Gain (loss) on extinguishment of debt |  |  |  | 45.1 | 174.3
$544.2 Million 7.75% 2020 Second Lien Notes |  |  |  |  |
Extinguishment of Debt [Line Items] |  |  |  |  |
Debt Extinguished |  |  |  | 430.1 |
Gain (loss) on extinguishment of debt |  |  |  | (104.5) | 6.9
$1.075 Billion 5.75% 2025 Senior Notes |  |  |  |  |
Extinguishment of Debt [Line Items] |  |  |  |  |
Debt Extinguished |  |  | 1.7 |  |
Gain (loss) on extinguishment of debt |  |  | 0.1 |  |
$400 Million 5.90% 2020 Senior Notes |  |  |  |  |
Extinguishment of Debt [Line Items] |  |  |  |  |
Debt Extinguished |  |  | 88.9 | 136.7 |
Gain (loss) on extinguishment of debt |  |  | (3.3) | (7.8) | 28.3
$500 Million 4.80% 2020 Senior Notes |  |  |  |  |
Extinguishment of Debt [Line Items] |  |  |  |  |
Debt Extinguished |  |  | 122.4 | 114.4 |
Gain (loss) on extinguishment of debt |  |  | (3.7) | (1.9) | 19.5
$700 Million 4.875% 2021 Senior Notes |  |  |  |  |
Extinguishment of Debt [Line Items] |  |  |  |  |
Debt Extinguished |  |  | 14.4 | 171.0 |
Gain (loss) on extinguishment of debt |  |  | $ 0.1 | $ (2.8) | $ 33.3

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