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REVENUE (Details) (USD $) | 12 Months Ended
--- | ---
Dec. 31, 2011 | Dec. 31, 2010 | Dec. 31, 2009
REVENUE [Abstract] |  |  |
Total number of vessels | 20 | 17 | 15
Number of vessels temporarily operated directly in the spot market | 6 | 0 | 4
Number of vessels were employed on bareboat charters |  | 2 | 2
Voyage revenues, net pool earnings | $ 76,618,000 | $ 119,598,000 | $ 102,229,000
Voyage revenues, gross freight through spot charters | 18,169,000 | 0 | 15,817,000
Bareboat revenues | 0 | 6,818,000 | 6,324,000
Total Voyage Revenues | 94,787,000 | 126,416,000 | 124,370,000
Concentration Risk [Line Items] |  |  |
Accounts receivable | 17,586,000 | 11,046,000 |
Accounts receivable, net related party | $ 1,600,000 |  |
Voyage Revenues [Member] | Gemini Tankers LLC [Member] |  |  |
Concentration Risk [Line Items] |  |  |
Concentration risk, percentage (in hundredths) | 97.00% | 78.00% |
Voyage Revenues [Member] | Orion Pool [Member] |  |  |
Concentration Risk [Line Items] |  |  |
Concentration risk, percentage (in hundredths) | 3.00% |  |
Voyage Revenues [Member] | Stena Pool [Member] |  |  |
Concentration Risk [Line Items] |  |  |
Concentration risk, percentage (in hundredths) |  | 17.00% | 41.00%
Voyage Revenues [Member] | Gemini Pool [Member] |  |  |
Concentration Risk [Line Items] |  |  |
Concentration risk, percentage (in hundredths) |  |  | 40.00%
Accounts Receivable [Member] | Gemini Tankers LLC [Member] |  |  |
Concentration Risk [Line Items] |  |  |
Concentration risk, percentage (in hundredths) | 99.00% | 100.00% |
Accounts Receivable [Member] | Stena Pool [Member] |  |  |
Concentration Risk [Line Items] |  |  |
Concentration risk, percentage (in hundredths) |  |  | 61.00%
Accounts Receivable [Member] | Gemini Pool [Member] |  |  |
Concentration Risk [Line Items] |  |  |
Concentration risk, percentage (in hundredths) |  |  | 33.00%
Accounts Receivable, Net Related Party [Member] | Orion Pool [Member] |  |  |
Concentration Risk [Line Items] |  |  |
Concentration risk, percentage (in hundredths) | 100.00% |  |

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