XML 55 R37.htm IDEA: XBRL DOCUMENT
v3.7.0.1

NATURE OF BUSINESS (Details) | 12 Months Ended |
--- | --- | ---
Dec. 31, 2016 Vessel t | Dec. 31, 2004 Vessel
NATURE OF BUSINESS [Abstract] |  |  |
Total number of vessels | Vessel |  | 33 | 3
Number of new buildings expected to be delivered in 2018 | Vessel |  | 3 |
Number of new buildings expected to be delivered in 2017 | Vessel |  | 1 |
Number of operating vessels | Vessel |  | 29 |
Number of vessels in construction | Vessel |  | 4 |
Average approximate deadweight tons per vessel |  | 156,000 |
Number of vessels build in Korea | Vessel |  | 31 |
Number of vessels under contract for construction | Vessel |  | 3 |
Nordic Harrier [Member] |  |  |
Schedule of Vessels [Line Items] |  |  |
Deadweight tons |  | 151,459 |
Nordic Hawk [Member] |  |  |
Schedule of Vessels [Line Items] |  |  |
Deadweight tons |  | 151,475 |
Nordic Hunter [Member] |  |  |
Schedule of Vessels [Line Items] |  |  |
Deadweight tons |  | 151,401 |
Nordic Voyager [Member] |  |  |
Schedule of Vessels [Line Items] |  |  |
Deadweight tons |  | 149,591 |
Nordic Fighter [Member] |  |  |
Schedule of Vessels [Line Items] |  |  |
Deadweight tons |  | 153,328 |
Nordic Freedom [Member] |  |  |
Schedule of Vessels [Line Items] |  |  |
Deadweight tons |  | 159,331 |
Nordic Discovery [Member] |  |  |
Schedule of Vessels [Line Items] |  |  |
Deadweight tons |  | 153,328 |
Nordic Saturn [Member] |  |  |
Schedule of Vessels [Line Items] |  |  |
Deadweight tons |  | 157,331 |
Nordic Jupiter [Member] |  |  |
Schedule of Vessels [Line Items] |  |  |
Deadweight tons |  | 157,411 |
Nordic Moon [Member] |  |  |
Schedule of Vessels [Line Items] |  |  |
Deadweight tons |  | 160,305 |
Nordic Apollo [Member] |  |  |
Schedule of Vessels [Line Items] |  |  |
Deadweight tons |  | 159,998 |
Nordic Cosmos [Member] |  |  |
Schedule of Vessels [Line Items] |  |  |
Deadweight tons |  | 159,999 |
Nordic Sprite [Member] |  |  |
Schedule of Vessels [Line Items] |  |  |
Deadweight tons |  | 147,188 |
Nordic Grace [Member] |  |  |
Schedule of Vessels [Line Items] |  |  |
Deadweight tons |  | 149,921 |
Nordic Mistral [Member] |  |  |
Schedule of Vessels [Line Items] |  |  |
Deadweight tons |  | 164,236 |
Nordic Passat [Member] |  |  |
Schedule of Vessels [Line Items] |  |  |
Deadweight tons |  | 164,274 |
Nordic Vega [Member] |  |  |
Schedule of Vessels [Line Items] |  |  |
Deadweight tons |  | 163,940 |
Nordic Breeze [Member] |  |  |
Schedule of Vessels [Line Items] |  |  |
Deadweight tons |  | 158,597 |
Nordic Aurora [Member] |  |  |
Schedule of Vessels [Line Items] |  |  |
Deadweight tons |  | 147,262 |
Nordic Zenith [Member] |  |  |
Schedule of Vessels [Line Items] |  |  |
Deadweight tons |  | 158,645 |
Nordic Sprinter [Member] |  |  |
Schedule of Vessels [Line Items] |  |  |
Deadweight tons |  | 159,089 |
Nordic Skier [Member] |  |  |
Schedule of Vessels [Line Items] |  |  |
Deadweight tons |  | 159,089 |
Nordic Light [Member] |  |  |
Schedule of Vessels [Line Items] |  |  |
Deadweight tons |  | 158,475 |
Nordic Cross [Member] |  |  |
Schedule of Vessels [Line Items] |  |  |
Deadweight tons |  | 158,475 |
Nordic Luna [Member] |  |  |
Schedule of Vessels [Line Items] |  |  |
Deadweight tons |  | 150,037 |
Nordic Castor [Member] |  |  |
Schedule of Vessels [Line Items] |  |  |
Deadweight tons |  | 150,249 |
Nordic Sirius [Member] |  |  |
Schedule of Vessels [Line Items] |  |  |
Deadweight tons |  | 150,183 |
Nordic Pollux [Member] |  |  |
Schedule of Vessels [Line Items] |  |  |
Deadweight tons |  | 150,103 |
Nordic Star [Member] |  |  |
Schedule of Vessels [Line Items] |  |  |
Deadweight tons |  | 159,000 |
Nordic Space [Member] |  |  |
Schedule of Vessels [Line Items] |  |  |
Deadweight tons | [1] | 159,000 |
Newbuilding [Member] |  |  |
Schedule of Vessels [Line Items] |  |  |
Deadweight tons | [1],[2] | 157,000 |
Newbuilding [Member] |  |  |
Schedule of Vessels [Line Items] |  |  |
Deadweight tons | [1],[2] | 157,000 |
Newbuilding [Member] |  |  |
Schedule of Vessels [Line Items] |  |  |
Deadweight tons | [1],[2] | 157,000 |
[1] | Vessel under construction per December 31, 2016.
[2] | Expected delivery during the second half of 2018.

X
- Definition Refers to the average approximate deadweight tons per vessel. + References No definition available. + Details
Name: | nat_AverageApproximateDeadweightTonsPerVesselInDeadweightTons
Namespace Prefix: | nat_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | instant

X
- Definition The total sum of weights in metric tonnes that the vessel can carry on a defined loadline. + References No definition available. + Details
Name: | nat_DeadweightTonnage
Namespace Prefix: | nat_
Data Type: | num:massItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | nat_NatureOfBusinessAbstract
Namespace Prefix: | nat_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the number of new building in entities current fleet expected to be delivered in 2017. + References No definition available. + Details
Name: | nat_NumberOfNewBuildingExpectedToBeDeliveredIn2017
Namespace Prefix: | nat_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the number of new building in entities current fleet expected to be delivered in 2018. + References No definition available. + Details
Name: | nat_NumberOfNewBuildingExpectedToBeDeliveredIn2018
Namespace Prefix: | nat_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents number of vessels in operation in entities current fleet. + References No definition available. + Details
Name: | nat_NumberOfOperatingVessels
Namespace Prefix: | nat_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of vessels build in Korea + References No definition available. + Details
Name: | nat_NumberOfVesselsBuildInKorea
Namespace Prefix: | nat_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Represents number of vessels in construction in entities current fleet. + References No definition available. + Details
Name: | nat_NumberOfVesselsInConstruction
Namespace Prefix: | nat_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of vessels under contract for construction. + References No definition available. + Details
Name: | nat_NumberOfVesselsUnderContractForConstruction
Namespace Prefix: | nat_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | nat_ScheduleOfVesselsLineItems
Namespace Prefix: | nat_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The total number of vessels during the period, which may include crude oil tankers and new vessels under construction to be used in the normal conduct of business and not intended for resale. + References No definition available. + Details
Name: | nat_TotalNumberOfVessels
Namespace Prefix: | nat_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=nat_NordicHarrierMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=nat_NordicHawkMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=nat_NordicHunterMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=nat_NordicVoyagerMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=nat_NordicFighterMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=nat_NordicFreedomMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=nat_NordicDiscoveryMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=nat_NordicSaturnMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=nat_NordicJupiterMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=nat_NordicMoonMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=nat_NordicApolloMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=nat_NordicCosmosMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=nat_NordicSpriteMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=nat_NordicGraceMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=nat_NordicMistralMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=nat_NordicPassatMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=nat_NordicVegaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=nat_NordicBreezeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=nat_NordicAuroraMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=nat_NordicZenithMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=nat_NordicSprinterMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=nat_NordicSkierMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=nat_NordicLightMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=nat_NordicCrossMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=nat_NordicLunaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=nat_NordicCastorMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=nat_NordicSiriusMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=nat_NordicPolluxMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=nat_NordicStarMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=nat_NordicSpaceMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=nat_NewbuildingoneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=nat_Newbuild2Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PropertyPlantAndEquipmentByTypeAxis=nat_Newbuild3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |