Dedesignation of interest rate swap agreements during the period.

No definition available.

Name:	osgiq_DedesignationOfInterestRateSwapAgreements
Namespace Prefix:	osgiq_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

This item represents percentage of concentrations of credit risk on voyage revenue accounted on pool.

+ References

No definition available.

+ Details

Name:	osgiq_FairValueConcentrationOFriskConsolidatedVoyageReceivablePercentage
Namespace Prefix:	osgiq_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

This item represents percentage of concentrations of credit risk on revenue from an individual counterparty or groups of counterparties.

+ References

No definition available.

+ Details

Name:	osgiq_FairValueConcentrationOfRiskRevenueAccountedForIndividualCustomersPercentage
Namespace Prefix:	osgiq_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The outstanding interest rate swap including accrued interest during the period.

+ References

No definition available.

+ Details

Name:	osgiq_OutstandingInterestRateSwap
Namespace Prefix:	osgiq_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 14

-URI http://asc.fasb.org/extlink&oid=20435746&loc=d3e681-108580

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 11

-URI http://asc.fasb.org/extlink&oid=20435746&loc=d3e637-108580

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 14A

-URI http://asc.fasb.org/extlink&oid=20435746&loc=SL7669686-108580

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 12

-Paragraph 10

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 31

-Article 5

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS115-1/124-1

-Paragraph 15D

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 130

-Paragraph 14, 17, 26

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

+ Details

Name:	us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

High end of the range of fixed interest rates when a range is presented for a group of interest rate derivatives.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeHigherFixedInterestRateRange
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Low end of the range of fixed interest rates when a range is presented for a group of interest rate derivatives.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeLowerFixedInterestRateRange
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeMaturityDates
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Aggregate notional amount of all foreign currency derivatives not designated as hedging instruments. Notional amount refers to the number of currency units specified in the foreign currency derivative contract.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1A

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5579245-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Notional Amount

-URI http://asc.fasb.org/extlink&oid=6519104

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1B

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5580258-113959

+ Details

Name:	us-gaap_NotionalAmountOfForeignCurrencyDerivativeInstrumentsNotDesignatedAsHedgingInstruments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Aggregate notional amount of all interest rate derivatives designated as hedging instruments in cash flow hedges. Notional amount refers to the monetary amount specified in the interest rate derivative contract.

+ References

+ Details

Name:	us-gaap_NotionalAmountOfInterestRateCashFlowHedgeDerivatives
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Fair Value of Financial Instruments, Derivatives and Fair Value Disclosures (Details Textual) In Thousands, unless otherwise specified	3 Months Ended			12 Months Ended				3 Months Ended
	Mar. 31, 2013 USD ($)	Mar. 31, 2012 USD ($)	Mar. 31, 2012 EUR (€)	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Mar. 31, 2013 Interest Rate Swap [Member] USD ($)	Sep. 30, 2012 Interest Rate Swap [Member] USD ($)	Mar. 31, 2013 Interest Rate Swap [Member] Maximum [Member]	Mar. 31, 2013 Interest Rate Swap [Member] Minimum [Member]	Mar. 31, 2013 Floating To Fixed Interest Rate Swap Agreements [Member] USD ($)
Derivative, Maturity Date								Aug. 31, 2014	Dec. 31, 2012
Notional Amount of Interest Rate Cash Flow Hedge Derivatives						$ 219,940				$ 30,000
Derivative, Lower Fixed Interest Rate Range						3.30%
Derivative, Higher Fixed Interest Rate Range						4.70%
Accumulated other comprehensive loss	(105,581)	(109,737)		(113,781)	(119,307)		331
Outstanding Interest Rate Swap	3,566
Dedesignation of interest rate swap agreements	1,866
Fair Value Concentration of Risk Revenue Accounted for Individual Customers Percentage	10.00%	10.00%	10.00%
Fair Value Concentration of Risk Consolidated Voyage Receivable Percentage	65.00%			59.00%
Notional Amount of Foreign Currency Derivative Instruments Not Designated as Hedging Instruments			€ 4,000