XML 35 R56.htm IDEA: XBRL DOCUMENT
v2.4.0.8

COMMITMENTS AND CONTINGENCIES (Details) (USD $) In Millions, unless otherwise specified |  |  |  | 12 Months Ended | 0 Months Ended | 1 Months Ended
--- | --- | --- | --- | --- | --- | ---
Dec. 31, 2013 Claim | Dec. 31, 2012 Claim | Dec. 31, 2011 Claim | Dec. 31, 2013 Gulf Navigation Holding PSJ [Member] | Jan. 31, 2014 Subsequent Event [Member] Gulf Navigation Holding PSJ [Member] | Jan. 31, 2014 Subsequent Event [Member] Gulf Navigation Holding PSJ [Member]
Subsequent Event [Line Items] |  |  |  |  |  |
Period of charter |  |  |  | 6 years |  |
Damages awarded |  |  |  |  | $ 10.2 | $ 10.2
Number of claims filed | 0 | 0 | 0 |  |  |

X
- Definition Refers to period for bareboat charter. + References No definition available. + Details
Name: | nat_PeriodOfCharter
Namespace Prefix: | nat_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of damages awarded to the plaintiff in the legal matter. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14326-108349 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14435-108349 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 9 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14557-108349 + Details
Name: | us-gaap_LossContingencyDamagesAwardedValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Number of pending claims pertaining to a loss contingency. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 450 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14435-108349 + Details
Name: | us-gaap_LossContingencyPendingClaimsNumber
Namespace Prefix: | us-gaap_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | us-gaap_SubsequentEventLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration