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LONG-TERM DEBT - Schedule Of Cash Flow Hedges Related to Derivative Instruments On the Balance Sheet (Details) - USD ($) $ in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2019 | Mar. 31, 2018 | Dec. 31, 2018
Derivatives, Fair Value [Line Items] |  |  |
Cash flow hedge derivatives, assets | $ 412 |  | $ 820
Cash flow hedge derivatives, liabilities | 3,012 |  | 1,942
Unrealized (loss) gain resulting from changes in fair value of derivative instruments | (1,554) | $ 785 |
Other current assets | Designated as Hedging Instrument | Interest rate swaps |  |  |
Derivatives, Fair Value [Line Items] |  |  |
Cash flow hedge derivatives, assets | 260 |  | 338
Other non-current assets | Designated as Hedging Instrument | Interest rate swaps |  |  |
Derivatives, Fair Value [Line Items] |  |  |
Cash flow hedge derivatives, assets | 152 |  | 482
Other accrued liabilities | Designated as Hedging Instrument | Interest rate swaps |  |  |
Derivatives, Fair Value [Line Items] |  |  |
Cash flow hedge derivatives, liabilities | 579 |  | 387
Other long-term liabilities | Designated as Hedging Instrument | Interest rate swaps |  |  |
Derivatives, Fair Value [Line Items] |  |  |
Cash flow hedge derivatives, liabilities | 2,433 |  | 1,555
Accumulated other comprehensive loss | Designated as Hedging Instrument | Interest rate swaps |  |  |
Derivatives, Fair Value [Line Items] |  |  |
Unrealized (loss) gain resulting from changes in fair value of derivative instruments | (2,753) |  | (1,196)
Accumulated other comprehensive loss, interest rate swaps - tax provision | (112) |  | (112)
Accumulated other comprehensive loss | $ (2,865) |  | $ (1,308)

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