XML 169 R45.htm IDEA: XBRL DOCUMENT
v3.19.1

Summary of Significant Accounting Policies (Details) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2018 USD ($) Vessel Unit Subsidiary | Dec. 31, 2017 USD ($) Vessel Unit Subsidiary | Dec. 31, 2016 USD ($) Vessel Subsidiary
Significant Accounting Policies [Line Items] |  |  |
Allowances for doubtful accounts | $ 0 | $ 0 |
Capitalized interest | $ 0 | $ 0 |
Depreciation method | straight-line |  |
Vessel estimated useful life | 30 years |  |
Period between scheduled regulatory drydockings | 5 years |  |
Forecast Rate Period following charter expiry | 4 years |  |
Future charter rate assumptions | charter rates on expiry of existing charters, which are based on forecast charter rates, where relevant, in the four years from the date of the impairment test and a reversion to the historical mean for each vessel thereafter |  |
Number of vessels tested for impairment | Vessel | 19 |  |
Number of vessels on which impairment charge is recognized | Vessel | 3 | 5 | 6
Vessel impairment charges | $ 71,834 | $ 87,624 | $ 92,422
Deferred tax liability recognized | $ 9 | $ 17 |
Number of banks holding deposits | Unit | 8 | 3 |
Number of Reportable Segments | Unit | 1 |  |
Property, Plant and Equipment, Net | $ 1,112,766 | $ 586,520 |
Restatement Adjustment [Member] | Accounting Standards Update 2016-15 [Member] |  |  |
Significant Accounting Policies [Line Items] |  |  |
Effect in net cash provided by operating activities |  | 9,047 | 533
Effect in net cash used in financing activities |  | $ 9,047 | $ 533
UNITED KINGDOM |  |  |
Significant Accounting Policies [Line Items] |  |  |
Number of subsidiaries owned by the Company | Subsidiary | 1 | 1 | 1
Principal rate of corporate income tax | 19.00% | 19.00% | 20.00%
Three Vessel Groups [Member] |  |  |
Significant Accounting Policies [Line Items] |  |  |
Vessel impairment charges | $ 71,834 |  |
Property, Plant and Equipment, Net | 165,334 |  |
Property, Plant, and Equipment, Fair Value Disclosure | $ 93,500 |  |
Impaired Long-Lived Assets Held and Used, Asset Description | Three vessel groups that are held and used |  |
Impaired Long-Lived Assets Held and Used, Method for Determining Fair Value | The estimated fair value, measured on a non - recurring basis, of the Company’s relevant three vessel groups that are held and used is calculated with the assistance of valuation obtained by third party independent ship brokers. Therefore, the Company has categorized the fair value of these vessels as Level II in the fair value hierarchy. |  |
Series B Preferred Shares [Member] |  |  |
Significant Accounting Policies [Line Items] |  |  |
Preferred shares dividend rate percentage | 8.75% |  |

X
- Definition Charter rates on expiry of existing charters, which are based on forecast charter rates, where relevant, for the four years from the date of the impairment test and a reversion to the historical mean for each vessel thereafter. + References No definition available. + Details
Name: | gsl_FutureCharterRateAssumptions
Namespace Prefix: | gsl_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of the effect of a change in accounting principle on net cash provided by financing activities. + References No definition available. + Details
Name: | gsl_NewAccountingPronouncementOrChangeInAccountingPrincipleEffectOfChangeOnNetCashProvidedByFinancingActivities
Namespace Prefix: | gsl_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of the effect of a change in accounting principle on net cash provided by operating activities. + References No definition available. + Details
Name: | gsl_NewAccountingPronouncementOrChangeInAccountingPrincipleEffectOfChangeOnNetCashProvidedByOperatingActivities
Namespace Prefix: | gsl_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The number of banks in which all of the company’s amounts are deposited, giving rise to a concentration of credit risk. + References No definition available. + Details
Name: | gsl_NumberOfBanksHoldingDeposits
Namespace Prefix: | gsl_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number Of Subsidiaries. + References No definition available. + Details
Name: | gsl_NumberOfSubsidiaries
Namespace Prefix: | gsl_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition The number of vessels on which impairment charge was recognized. + References No definition available. + Details
Name: | gsl_NumberOfVesselsImpairmentChargeRecognized
Namespace Prefix: | gsl_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition The number of vessels tested for impairment. + References No definition available. + Details
Name: | gsl_NumberOfVesselsTestedForImpairment
Namespace Prefix: | gsl_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Period between scheduled drydockings. + References No definition available. + Details
Name: | gsl_PeriodBetweenScheduledDrydockings
Namespace Prefix: | gsl_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition The period from the impairment test date in which, after the current charter expires, forecast rates are adopted and a reversion to the historical mean thereafter. + References No definition available. + Details
Name: | gsl_PeriodFromImpairmentTestDateInWhichAfterCurrentCharterExpiresForecastRatesAdopted
Namespace Prefix: | gsl_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Significant Accounting Policies [Line Items] + References No definition available. + Details
Name: | gsl_SignificantAccountingPoliciesLineItems
Namespace Prefix: | gsl_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition A valuation allowance for trade and other receivables due to an Entity within one year (or the normal operating cycle, whichever is longer) that are expected to be uncollectible. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5074-111524 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.4) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount, after deferred tax asset, of deferred tax liability attributable to taxable differences, with jurisdictional netting and classified as noncurrent. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 45 -Paragraph 9 -URI http://asc.fasb.org/extlink&oid=84176650&loc=d3e31958-109318 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 45 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=84176650&loc=d3e31931-109318 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=84176650&loc=d3e31917-109318 + Details
Name: | us-gaap_DeferredTaxLiabilitiesNoncurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(h)(2)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32687-109319 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 13 -URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32698-109319 + Details
Name: | us-gaap_EffectiveIncomeTaxRateContinuingOperations
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition A description of the impaired assets to be held and used by the entity. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=109226691&loc=d3e2921-110230 + Details
Name: | us-gaap_ImpairedLongLivedAssetsHeldAndUsedAssetDescription
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition A description of how an entity determined the fair value of the long-lived asset they are holding and using, for example, whether based on a quoted market price, prices for similar assets, or another valuation technique. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=109226691&loc=d3e2921-110230 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SAB Topic 5.CC) -URI http://asc.fasb.org/extlink&oid=27011434&loc=d3e125687-122742 + Details
Name: | us-gaap_ImpairedLongLivedAssetsHeldAndUsedMethodForDeterminingFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of interest capitalized during the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6450988&loc=d3e26243-108391 + Details
Name: | us-gaap_InterestCostsCapitalized
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements. + References No definition available. + Details
Name: | us-gaap_NumberOfReportableSegments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition The percentage rate used to calculate dividend payments on preferred stock. + References No definition available. + Details
Name: | us-gaap_PreferredStockDividendRatePercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Description of the methodology for computing depreciation for classes of depreciable assets. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229 + Details
Name: | us-gaap_PropertyPlantAndEquipmentDepreciationMethods
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Fair value portion of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19190-110258 + Details
Name: | us-gaap_PropertyPlantAndEquipmentFairValueDisclosure
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(14)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(8)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(13)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_PropertyPlantAndEquipmentNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment. + References No definition available. + Details
Name: | us-gaap_PropertyPlantAndEquipmentUsefulLife
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition The charge against earnings resulting from the aggregate write down of tangible assets from their carrying value to their fair value. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109226691&loc=d3e2921-110230 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109222650&loc=d3e1361-107760 + Details
Name: | us-gaap_TangibleAssetImpairmentCharges
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | srt_RestatementAxis=srt_RestatementAdjustmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AdjustmentsForNewAccountingPronouncementsAxis=us-gaap_AccountingStandardsUpdate201615Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementGeographicalAxis=country_GB
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ImpairedLongLivedAssetsHeldAndUsedByTypeAxis=gsl_ThreeVesselGroupsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementClassOfStockAxis=us-gaap_SeriesBPreferredStockMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |