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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) | 12 Months Ended
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Dec. 31, 2020 USD ($) Segment Customer Vessel Subsidiary Agreement Charter | Dec. 31, 2019 USD ($) Customer Charter | Dec. 31, 2018 USD ($) Customer
Cash, Cash Equivalents and Restricted Cash [Abstract] |  |  |
Original maturities of deposits classified as cash and cash equivalents | 3 months |  |
Vessels [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 | $ 8,000,000.0 |  |
Drydocking [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 | 2 |  |
Post Retirement Benefits [Abstract] |  |  |
Expense (gain) recognized | $ (71,000) | $ (10,970,000) | $ (860,000)
Segment Information [Abstract] |  |  |
Number of segments | Segment | 1 |  |
Number of types of vessel | Vessel | 1 |  |
Income Tax [Abstract] |  |  |
Income tax rate | 0.00% |  |
Income tax expense | $ 64,000 | 71,000 | 79,000
Concentration of Risk [Abstract] |  |  |
Accounts receivable, net | 6,300,000 | 24,600,000 |
Provision for credit losses | 25,000,000 | 0 |
Recent Accounting Pronouncements [Abstract] |  |  |
Right of Use Assets | $ 1,219,000 | 1,412,000 |
Chief Executive Officer and Chief Financial Officer [Member] |  |  |
Post Retirement Benefits [Abstract] |  |  |
Expense (gain) recognized |  | $ (200,000) | $ (700,000)
Ballast Tank [Member] |  |  |
Drydocking [Abstract] |  |  |
Improvements amortized over a period | 8 years |  |
Norwegian Tax Administration [Member] |  |  |
Income Tax [Abstract] |  |  |
Number of wholly owned subsidiaries | Subsidiary | 2 |  |
Income tax rate | 22.00% | 22.00% | 23.00%
Income tax expense | $ 64,000 | $ 71,000 | $ 79,000
Accounts Receivable [Member] | Two Charterers [Member] |  |  |
Concentration of Risk [Abstract] |  |  |
Number of charterers accounted for outstanding amount | Charter | 2 |  |
Accounts Receivable [Member] | Three Charterers [Member] |  |  |
Concentration of Risk [Abstract] |  |  |
Number of charterers accounted for outstanding amount | Charter |  | 3 |
Accounts Receivable [Member] | Customer Concentration Risk [Member] | Two Charterers [Member] |  |  |
Concentration of Risk [Abstract] |  |  |
Concentration of credit risk percentage | 39.00% |  |
Accounts Receivable [Member] | Customer Concentration Risk [Member] | Three Charterers [Member] |  |  |
Concentration of Risk [Abstract] |  |  |
Concentration of credit risk percentage |  | 48.00% |
Accounts Receivable [Member] | Customer Concentration Risk [Member] | Charterer One [Member] |  |  |
Concentration of Risk [Abstract] |  |  |
Concentration of credit risk percentage | 22.00% | 19.00% |
Accounts Receivable [Member] | Customer Concentration Risk [Member] | Charterer Two [Member] |  |  |
Concentration of Risk [Abstract] |  |  |
Concentration of credit risk percentage | 17.00% | 15.00% |
Accounts Receivable [Member] | Customer Concentration Risk [Member] | Charterer Three [Member] |  |  |
Concentration of Risk [Abstract] |  |  |
Concentration of credit risk percentage |  | 14.00% |
Revenues [Member] | Customer Concentration Risk [Member] |  |  |
Concentration of Risk [Abstract] |  |  |
Number of customers | Customer |  |  | 0
Revenues [Member] | Customer Concentration Risk [Member] | One Customer [Member] |  |  |
Concentration of Risk [Abstract] |  |  |
Number of customers | Customer | 1 | 1 |
Concentration of credit risk percentage | 11.40% | 13.70% |
ASC 842 [Member] |  |  |
Recent Accounting Pronouncements [Abstract] |  |  |
Right of Use Assets |  | $ 500,000 | $ 1,900,000
Lease liability |  | $ 500,000 | $ 1,900,000

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