Entity Information (USD $)	3 Months Ended
	Mar. 31, 2012	May 01, 2012	Jun. 30, 2011
Entity Registrant Name	NATIONAL BANKSHARES INC
Entity Central Index Key	0000796534
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	No
Entity Filer Category	Accelerated Filer
Entity Public Float			$ 166,007,713
Entity Common Stock, Shares Outstanding		6,939,974
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	Q1