Leases (Details 1) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015
Operating Leases, Future Minimum Payments Receivable [Abstract]
Revenue Days	19844 days
One Year From Balance Sheet [Member]
Operating Leases, Future Minimum Payments Receivable [Abstract]
Revenue Days	7132 days
More Than One and Within Two Years From Balance Sheet [Member]
Operating Leases, Future Minimum Payments Receivable [Abstract]
Revenue Days	5194 days
More Than Two and Within Three Years From Balance Sheet [Member]
Operating Leases, Future Minimum Payments Receivable [Abstract]
Revenue Days	2808 days
More Than Three and Within Four Years From Balance Sheet [Member]
Operating Leases, Future Minimum Payments Receivable [Abstract]
Revenue Days	1699 days
More Than Four and Within Five Years From Balance Sheet [Member]
Operating Leases, Future Minimum Payments Receivable [Abstract]
Revenue Days	933 days
More Than Five Years From Balance Sheet and Thereafter [Member]
Operating Leases, Future Minimum Payments Receivable [Abstract]
Revenue Days	2078 days
Charter Out [Member]
Operating Leases, Future Minimum Payments Receivable [Abstract]
2015	324,838
2016	283,393
2017	178,914
2018	123,156
2019	78,067
Thereafter	176,082
Net minimum lease payments	1,164,450

Number of revenue days.

No definition available.

Name:	osgiq_NumberOfRevenueDays
Namespace Prefix:	osgiq_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Future minimum rental payments in aggregate as of the balance sheet date under operating leases.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 20

-Section 50

-Paragraph 4

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6454179&loc=d3e41551-112718

+ Details

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

- Details

Name:	us-gaap_OperatingLeasesFutureMinimumPaymentsReceivableAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Future rental payments receivable within one year of the balance sheet date under an operating lease.

+ References

+ Details

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

- Definition

Future rental payments receivable within the fifth year from the balance sheet date under an operating lease.

+ References

+ Details

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

- Definition

Future rental payments receivable within the fourth year from the balance sheet date under an operating lease.

+ References

+ Details

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

- Definition

Future rental payments receivable within the third year from the balance sheet date under an operating lease.

+ References

+ Details

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

- Definition

Future rental payments receivable within the second year from the balance sheet date under an operating lease.

+ References

+ Details

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

- Definition

Future minimum lease payments receivable under operating leases for periods greater than five years following the balance sheet date.

+ References

+ Details

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

- Details

Name:	us-gaap_PropertySubjectToOrAvailableForOperatingLeaseAxis=osgiq_CharterOutMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=osgiq_MoreThanFiveYearsFromBalanceSheetAndThereafterMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=osgiq_MoreThanFourAndWithinFiveYearsFromBalanceSheetMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=osgiq_MoreThanOneAndWithinTwoYearsFromBalanceSheetMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=osgiq_MoreThanThreeAndWithinFourYearsFromBalanceSheetMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=osgiq_MoreThanTwoAndWithinThreeYearsFromBalanceSheetMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=osgiq_OneYearFromBalanceSheetMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: