Document And Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2020	Mar. 02, 2021	Jun. 30, 2020
Document Information [Line Items]
Entity Central Index Key	0000859070
Entity Registrant Name	FIRST COMMUNITY BANKSHARES INC /VA/
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2020
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Document Transition Report	false
Entity File Number	000-19297
Entity Incorporation, State or Country Code	VA
Entity Tax Identification Number	55-0694814
Entity Address, Address Line One	P.O. Box 989
Entity Address, City or Town	Bluefield
Entity Address, State or Province	VA
Entity Address, Postal Zip Code	24605-0989
City Area Code	276
Local Phone Number	326-9000
Title of 12(b) Security	Common Stock, $1.00 par value
Trading Symbol	FCBC
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 282,850,000
Entity Common Stock, Shares Outstanding		17,641,124