Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

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-Name Regulation S-X (SX)

-Number 210

-Article 12

-Section 13

-Sentence Column B

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Initial term of contract.

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Storage capacity of each vessels.

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Fixed interest rate related to the interest rate derivative.

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The effective portion of net gain (loss) reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4C

-Subparagraph (c)

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The portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments representing (a) the amount of the hedge ineffectiveness and (b) the amount, if any, excluded from the assessment of hedge effectiveness.

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Date the derivative contract matures, in CCYY-MM-DD format.

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A description of the principal activities of an investee accounted for under the equity method.

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 323

-SubTopic 10

-Section 50

-Paragraph 3

-Subparagraph (a)(1)

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The amount of net gain (loss) reclassified into earnings when interest rate cash flow hedge is discontinued because it is probable that the original forecasted transactions will not occur by the end of the original period or an additional two month time period.

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- Definition

Indicates, if estimable, (as a percentage) the approximate extent to which the proceeds from liquidation of any assets held either as collateral or by third parties would be expected to cover the maximum potential amount of future payments under the guarantee or each group of similar guarantees.

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-Topic 460

-SubTopic 10

-Section 50

-Paragraph 4

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The carrying amount of the contractual right to receive fees, as compensation in exchange for providing a guarantee to a third party, over life of the guarantee.

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Fair value as of the balance sheet date of all interest rate derivative liabilities designated as cash flow hedging instruments.

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The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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-Topic 942

-SubTopic 210

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-Subparagraph (SX 210.9-03.16)

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Equity Method Investments (Details Textual) (USD $) In Thousands, unless otherwise specified	3 Months Ended	1 Months Ended	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Nov. 30, 2004	Mar. 31, 2014	Dec. 31, 2014
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Description Of Principal Activities	Maersk Oil Qatar AS awarded two service contracts to a joint venture between OSG and Euronav NV
Guaranty Assets	$ 0us-gaap_GuarantyAssets			$ 0us-gaap_GuarantyAssets
Liquid Natural Gas Carrier Vessel [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage		49.90%
Initial Term Of Contract		25 years
Ti Africa Vessel [Member]
Schedule of Equity Method Investments [Line Items]
Gain (Loss) on Discontinuation of Interest Rate Cash Flow Hedge Due to Forecasted Transaction Probable of Not Occurring, Net	301		106
Ti Asia Vessel [Member]
Schedule of Equity Method Investments [Line Items]
Effective Portion of Gain/(Loss) Reclassified from Accumulated Other Comprehensive Loss	2,706			2,944
Qatar Gas Transport Company Limited Nakilat Joint Venture [Member]
Schedule of Equity Method Investments [Line Items]
Storage Volume	four 216,200 cbm
Qatar Gas Transport Company Limited Nakilat Joint Venture [Member] \| Liquid Natural Gas Carrier Vessel [Member] \| Minimum [Member]
Schedule of Equity Method Investments [Line Items]
Derivative, Maturity Date	Jul. 01, 2022
Qatar Gas Transport Company Limited Nakilat Joint Venture [Member] \| Liquid Natural Gas Carrier Vessel [Member] \| Maximum [Member]
Schedule of Equity Method Investments [Line Items]
Derivative, Maturity Date	Nov. 30, 2022
Qatar Gas Transport Company Limited Nakilat Joint Venture and Euronav Nv Joint Venture [Member]
Schedule of Equity Method Investments [Line Items]
Derivative, Fixed Interest Rate	4.90%
Qatar Gas Transport Company Limited Nakilat Joint Venture and Euronav Nv Joint Venture [Member] \| Liquid Natural Gas Carrier Vessel [Member]
Schedule of Equity Method Investments [Line Items]
Line of Credit Facility, Amount Outstanding	706,348			715,378
Euronav Nv Joint Venture [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	50.00%
Equity Method Investment, Description Of Principal Activities	operates four LNG Carriers
Line of Credit Facility, Amount Outstanding	125,596			145,396
Notional Amount of Interest Rate Cash Flow Hedge Derivatives	228,186			254,308
Derivative, Fixed Interest Rate	3.90%
Interest Rate Cash Flow Hedge Liability at Fair Value	12,654			13,665
Guarantor Obligations, Liquidation Proceeds, Percentage	50.00%
Euronav Nv Joint Venture [Member] \| Minimum [Member]
Schedule of Equity Method Investments [Line Items]
Derivative, Maturity Date	Jul. 01, 2017
Euronav Nv Joint Venture [Member] \| Maximum [Member]
Schedule of Equity Method Investments [Line Items]
Derivative, Maturity Date	Sep. 30, 2017
Alaska Tanker Company LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage	37.50%
Qatar Liquefied Gas Company Limited [Member] \| Liquid Natural Gas Carrier Vessel [Member]
Schedule of Equity Method Investments [Line Items]
Effective Portion of Gain/(Loss) Reclassified from Accumulated Other Comprehensive Loss	61,183			58,240
Gain (Loss) on Discontinuation of Interest Rate Cash Flow Hedge Due to Forecasted Transaction Probable of Not Occurring, Net	122,713			116,819
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	$ 683,870			$ 693,072