COMMITMENTS AND CONTINGENCIES (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2011
COMMITMENTS AND CONTINGENCIES [Abstract]
Legal fees of the Seller	$ 1.2

The estimated amount of expense provided in the period for legal costs incurred on or before the balance sheet date pertaining to the expenses incurred by the seller in regards to pending litigation.

No definition available.

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