Scheduled Maturities of Certificates of Deposit of $250 Thousand or More (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Time deposit of $250 thousand or more
Three months or less	$ 6,813
Over three through six months	4,700
Over six through twelve months	7,401
Over twelve months	22,433
Total	$ 41,347	$ 60,270

Contractual Maturities, Time Deposits, $250,000 or More [Abstract]

No definition available.

Name:	fcbc_ContractualMaturitiesTimeDeposits250000OrMoreAbstract
Namespace Prefix:	fcbc_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Contractual Maturities, Time Deposits, $250,000 or More, after 12 Months

No definition available.

Name:	fcbc_ContractualMaturitiesTimeDeposits250000OrMoreAfter12Months
Namespace Prefix:	fcbc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Contractual Maturities, Time Deposits, $250,000 or More, Six Months Through 12 Months

No definition available.

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

Contractual Maturities, Time Deposits, $250,000 or More, Three Months or Less

No definition available.

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

Contractual Maturities, Time Deposits, $250,000 or More, Three Months Through Six Months

No definition available.

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

Time Deposits, $250,000 or More

No definition available.