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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2017 USD ($) Vessel Agreement Segment Subsidiary Customer Charter | Dec. 31, 2016 USD ($) Customer Charter | Dec. 31, 2015 USD ($) Customer
Cash and Cash Equivalents [Abstract] |  |  |
Original maturities of deposits classified as cash and cash equivalents | 3 months |  |
Accounts Receivable [Abstract] |  |  |
Allowance for doubtful balances | $ 0 | $ 150,000 |
Vessels, Net [Abstract] |  |  |
Estimate useful life of vessel | 25 years |  |
Market rates for the initial period | 2 years |  |
Historical and average spot market rate | 15 years |  |
Salvage value of the vessel | $ 8,000 |  |
Drydock [Abstract] |  |  |
Period when vessels are required to be drydocked, minimum | 30 months |  |
Period when vessels are required to be drydocked, maximum | 60 months |  |
Deferred Compensation Liability [Abstract] |  |  |
Number of individual deferred compensation agreements | Agreement | 1 |  |
Segment Information [Abstract] |  |  |
Number of operating segment | Segment | 1 |  |
Number of types of vessel | Vessel | 1 |  |
Income Taxes [Abstract] |  |  |
Statutory rate of corporate earnings | 0.00% |  |
Number of wholly owned subsidiaries | Subsidiary | 2 |  |
Income tax rate for wholly-owned subsidiaries in Norway | 24.00% | 25.00% | 27.00%
Income tax expense | $ 83 | $ 102 | $ 96
Concentration Risk [Line Items] |  |  |
Accounts receivable, net | 21,700 | 17,500 |
Recent Accounting Pronouncements [Abstract] |  |  |
Accrued voyage expenses | $ 10,873 | $ 9,583 |
Ballast Tank [Member] |  |  |
Drydock [Abstract] |  |  |
Improvements amortized over a period | 8 years |  |
Accounts Receivable [Member] |  |  |
Concentration Risk [Line Items] |  |  |
Concentration of credit risk percentage | 25.00% | 44.00% |
Number of charterers accounted for outstanding amount | Charter | 2 | 3 |
Accounts Receivable [Member] | Customer One [Member] |  |  |
Concentration Risk [Line Items] |  |  |
Concentration of credit risk percentage | 11.00% | 16.00% |
Accounts Receivable [Member] | Customer Two [Member] |  |  |
Concentration Risk [Line Items] |  |  |
Concentration of credit risk percentage | 14.00% | 16.00% |
Accounts Receivable [Member] | Customer Three [Member] |  |  |
Concentration Risk [Line Items] |  |  |
Concentration of credit risk percentage |  | 12.00% |
Revenues [Member] |  |  |
Concentration Risk [Line Items] |  |  |
Number of customers accounted for total revenues | Customer | 1 | 1 | 2
Concentration of credit risk percentage | 12.00% | 32.00% | 42.00%
Revenues [Member] | Customer One [Member] |  |  |
Concentration Risk [Line Items] |  |  |
Concentration of credit risk percentage |  |  | 30.00%
Revenues [Member] | Customer Two [Member] |  |  |
Concentration Risk [Line Items] |  |  |
Concentration of credit risk percentage |  |  | 12.00%
ASU 2014-09 [Member] |  |  |
Recent Accounting Pronouncements [Abstract] |  |  |
Reduction of accrued revenue | $ 5,300 |  |
Accrued voyage expenses | 600 |  |
Recognition of capitalized fulfillment cost | 600 |  |
ASU 2016-18 [Member] |  |  |
Recent Accounting Pronouncements [Abstract] |  |  |
Amount reclassified from investing activities | $ 5,000 |  |

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