Document And Entity Information	3 Months Ended
	Mar. 31, 2014	May 01, 2014
Document and Entity Information [Abstract]
Entity Registrant Name	NATIONAL BANKSHARES INC
Document Type	10-Q
Current Fiscal Year End Date	--12-31
Entity Common Stock, Shares Outstanding		6,947,974
Amendment Flag	false
Entity Central Index Key	0000796534
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Accelerated Filer
Entity Well-known Seasoned Issuer	No
Document Period End Date	Mar. 31, 2014
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	Q1