Name:	fcbc_ContractualMaturitiesTimeDeposits250000OrMoreAfter12Months
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Period Type:	instant

Amount of time deposit liabilities, including certificates of deposit, in denominations of $250,000 or more, maturing within six to twelve months after the balance sheet date.

No definition available.

Name:	fcbc_ContractualMaturitiesTimeDeposits250000OrMoreSixMonthsThrough12Months
Namespace Prefix:	fcbc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount of time deposit liabilities, including certificates of deposit, in denominations of $250,000 or more, maturing within three months or fewer from the balance sheet date.

No definition available.

Name:	fcbc_ContractualMaturitiesTimeDeposits250000OrMoreThreeMonthsOrLess
Namespace Prefix:	fcbc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount of time deposit liabilities, including certificates of deposit, in denominations of $250,000 or more, maturing within three to six months after the balance sheet date.

No definition available.

Name:	fcbc_ContractualMaturitiesTimeDeposits250000OrMoreThreeMonthsThroughSixMonths
Namespace Prefix:	fcbc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount of time deposit liabilities, including certificates of deposit, in denominations that meet or exceed the Federal Deposit Insurance Corporation (FDIC) insurance limit.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-SubTopic 405
-Topic 942
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481047/942-405-50-1