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COMMITMENTS AND CONTINGENCIES (Details)	12 Months Ended
	Dec. 31, 2020 Building Claim	Dec. 31, 2019 Claim
COMMITMENTS AND CONTINGENCIES [Abstract]
Number of claims filed | Claim	0	0
Number of new buildings | Building	2

X

- Definition

Refers to be number of new buildings.

+ References

No definition available.

+ Details

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Namespace Prefix:	nat_
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Balance Type:	na
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X

- References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
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X

- Definition

Number of pending claims pertaining to a loss contingency.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14435-108349

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