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REVENUE (Details) (USD $) | 12 Months Ended |
--- | --- | ---
Dec. 31, 2012 | Dec. 31, 2011 | Dec. 31, 2010 | Dec. 31, 2004
REVENUE [Abstract] |  |  |  |
Number of vessels were employed on spot market during the period |  |  | 15 |
Total number of vessels | 20 | 17 | 17 | 3
Number of vessels temporarily operated directly in the spot market | 6 | 6 | 0 |
Number of vessels were employed on bareboat charters |  |  | 2 |
Net pool spot market earnings, cooperative arrangements | $ 77,287,000 | $ 76,618,000 | $ 119,598,000 |
Gross pool spot market earnings, Orion Tankers pool | 36,339,000 | 0 | 0 |
Gross spot market earnings, through spot charters | 17,056,000 | 18,169,000 | 0 |
Bareboat revenues | 0 | 0 | 6,818,000 |
Total Voyage Revenues | 130,682,000 | 94,787,000 | 126,416,000 |
Number of tankers withdrawn from pool | 9 |  |  |
Concentration Risk [Line Items] |  |  |  |
Accounts receivable | 10,000 | 17,600,000 |  |
Orion Tankers Pool [Member] |  |  |  |
Concentration Risk [Line Items] |  |  |  |
Accounts receivable, net related party | $ 12,900,000 | $ 1,600,000 |  |
Voyage Revenues [Member] | Gemini Tankers LLC [Member] |  |  |  |
Concentration Risk [Line Items] |  |  |  |
Concentration risk, percentage (in hundredths) | 2.00% | 97.00% | 78.00% |
Voyage Revenues [Member] | Orion Tankers Pool [Member] |  |  |  |
Concentration Risk [Line Items] |  |  |  |
Concentration risk, percentage (in hundredths) | 98.00% | 3.00% |  |
Voyage Revenues [Member] | Stena Pool [Member] |  |  |  |
Concentration Risk [Line Items] |  |  |  |
Concentration risk, percentage (in hundredths) |  |  | 17.00% |
Accounts Receivable [Member] | Gemini Tankers LLC [Member] |  |  |  |
Concentration Risk [Line Items] |  |  |  |
Concentration risk, percentage (in hundredths) |  | 99.00% | 100.00% |
Accounts Receivable, Net Related Party [Member] | Orion Tankers Pool [Member] |  |  |  |
Concentration Risk [Line Items] |  |  |  |
Concentration risk, percentage (in hundredths) | 100.00% | 100.00% |  |

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