XML 59 R43.htm IDEA: XBRL DOCUMENT v3.3.1.900

RELATED PARTY TRANSACTIONS (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Related Party Transaction [Line Items]
Warrants received (in shares)			833,333
Warrants exercise price (in dollars per share)			$ 15.00
Percentage of warrants vesting increments			20.00%
Percentages of increase in volume weighted average price			10.00%
Minimum business days required for exercise level of VWAP			10 days
VWAP minimum trading volume of exercise levels			$ 2,000
Minimum [Member]
Related Party Transaction [Line Items]
Percentage of common shares increase			25.00%
Maximum [Member]
Related Party Transaction [Line Items]
Percentage of common shares increase			65.00%
Scandic American Shipping Ltd [Member]
Related Party Transaction [Line Items]
New amount of management fee due to decrease in the period		$ 150,000
Board Member [Member]
Related Party Transaction [Line Items]
Accounts payable	$ 0	0
Costs and expenses, related party	100	100	$ 100
Immediate Family Member of the Chairman [Member]
Related Party Transaction [Line Items]
Costs and expenses, related party	100	100
Nordic American Offshore Limited [Member]
Related Party Transaction [Line Items]
Costs and expenses, related party	$ 2,100	$ 2,200	$ 300
Increment exercisable percentage		20.00%
Success fees services		$ 1,500

X

- Definition

Represents minimum business days required for exercise level.

+ References

No definition available.

+ Details

Name:	nat_MinimumBusinessDaysRequiredForExerciseLevel
Namespace Prefix:	nat_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Represents minimum trading volume of exercise levels on balance sheet date.

+ References

No definition available.

+ Details

Name:	nat_MinimumTradingVolumeOfExerciseLevels
Namespace Prefix:	nat_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Represents percentage of common shares increase during the period.

+ References

No definition available.

+ Details

Name:	nat_PercentageOfCommonSharesIncrease
Namespace Prefix:	nat_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Refers to Percentage of incremental increase in the VWAP that causes vesting to increment.

+ References

No definition available.

+ Details

Name:	nat_PercentageOfIncrementalIncreaseInVwapThatCausesVestingToIncrementInHundredths
Namespace Prefix:	nat_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Represents percentage of warrants vesting increments during the period.

+ References

No definition available.

+ Details

Name:	nat_PercentageOfWarrantsVestingIncrements
Namespace Prefix:	nat_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Represents percentages of increase in volume weighted average price during the period.

+ References

No definition available.

+ Details

Name:	nat_PercentagesOfIncreaseInVolumeWeightedAveragePrice
Namespace Prefix:	nat_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Definition

New amount of management fee due to (decrease) increase during the period.

+ References

No definition available.

+ Details

Name:	nat_RelatedPartyTransactionNewAmountOfManagementFeeDueToDecreaseIncreaseInPeriod
Namespace Prefix:	nat_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

Exercise price per share or per unit of warrants or rights outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(i)(4))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

Name:	us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Number of warrants or rights outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(i))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

Name:	us-gaap_ClassOfWarrantOrRightOutstanding
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Costs of sales and operating expenses for the period incurred from transactions with related parties.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.2)
-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

+ Details

Name:	us-gaap_CostsAndExpensesRelatedParty
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

Carrying amount as of the balance sheet date of obligations due all related parties. For classified balance sheets, represents the current portion of such liabilities (due within one year or within the normal operating cycle if longer).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(k)(1))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(a))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

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

X

- Definition

Amount of fees from providing shareholder services, including, but not limited to, answering shareholder inquiries and providing shareholders with information about their investments.

+ References

No definition available.

+ Details

Name:	us-gaap_ServicingFees
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Details

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

X

- Details

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

X

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=nat_ScandicAmericanShippingLtdMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=us-gaap_DirectorMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=us-gaap_ImmediateFamilyMemberOfManagementOrPrincipalOwnerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=nat_NordicAmericanOffshoreLimitedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: