Nonaccrual Loans by Loan Class (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Financing Receivable, Impaired [Line Items]
Total	$ 12,994fcbc_GrossNonaccrualLoans	$ 22,506fcbc_GrossNonaccrualLoans
Purchased impaired loans		8fcbc_AcquiredImpairedLoans
Total nonaccrual loans	12,994fcbc_NetNonaccrualLoans	22,514fcbc_NetNonaccrualLoans
Commercial Loans \| Construction Development And Other Land
Financing Receivable, Impaired [Line Items]
Total	18	1,948
Commercial Loans \| Commercial and Industrial
Financing Receivable, Impaired [Line Items]
Total	157	5,433
Commercial Loans \| Multi-family Residential
Financing Receivable, Impaired [Line Items]
Total	245
Commercial Loans \| Single-family Non-owner Occupied
Financing Receivable, Impaired [Line Items]
Total	678	2,188
Commercial Loans \| Non-farm, Non-residential
Financing Receivable, Impaired [Line Items]
Total	3,651	2,685
Commercial Loans \| Agricultural
Financing Receivable, Impaired [Line Items]
Total	4
Commercial Loans \| Farmland Loan
Financing Receivable, Impaired [Line Items]
Total		742
Consumer Real Estate \| Home Equity Lines
Financing Receivable, Impaired [Line Items]
Total	996	997
Consumer Real Estate \| Single Family Owner Occupied
Financing Receivable, Impaired [Line Items]
Total	7,071	8,122
Consumer Real Estate \| Owner occupied construction
Financing Receivable, Impaired [Line Items]
Total	106	190
Consumer and Other \| Consumer Loan
Financing Receivable, Impaired [Line Items]
Total	68	201
Non Covered Loans
Financing Receivable, Impaired [Line Items]
Total	10,556	19,153
Purchased impaired loans		8
Total nonaccrual loans	10,556	19,161
Non Covered Loans \| Commercial Loans \| Construction Development And Other Land
Financing Receivable, Impaired [Line Items]
Total		1,187
Non Covered Loans \| Commercial Loans \| Commercial and Industrial
Financing Receivable, Impaired [Line Items]
Total	123	5,341
Non Covered Loans \| Commercial Loans \| Multi-family Residential
Financing Receivable, Impaired [Line Items]
Total	245
Non Covered Loans \| Commercial Loans \| Single-family Non-owner Occupied
Financing Receivable, Impaired [Line Items]
Total	601	1,966
Non Covered Loans \| Commercial Loans \| Non-farm, Non-residential
Financing Receivable, Impaired [Line Items]
Total	2,334	2,685
Non Covered Loans \| Commercial Loans \| Agricultural
Financing Receivable, Impaired [Line Items]
Total	4
Non Covered Loans \| Commercial Loans \| Farmland Loan
Financing Receivable, Impaired [Line Items]
Total		441
Non Covered Loans \| Consumer Real Estate \| Home Equity Lines
Financing Receivable, Impaired [Line Items]
Total	792	765
Non Covered Loans \| Consumer Real Estate \| Single Family Owner Occupied
Financing Receivable, Impaired [Line Items]
Total	6,389	6,567
Non Covered Loans \| Consumer and Other \| Consumer Loan
Financing Receivable, Impaired [Line Items]
Total	68	201
Covered Loans
Financing Receivable, Impaired [Line Items]
Total	2,438	3,353
Total nonaccrual loans	2,438	3,353
Covered Loans \| Commercial Loans \| Construction Development And Other Land
Financing Receivable, Impaired [Line Items]
Total	18	761
Covered Loans \| Commercial Loans \| Commercial and Industrial
Financing Receivable, Impaired [Line Items]
Total	34	92
Covered Loans \| Commercial Loans \| Single-family Non-owner Occupied
Financing Receivable, Impaired [Line Items]
Total	77	222
Covered Loans \| Commercial Loans \| Non-farm, Non-residential
Financing Receivable, Impaired [Line Items]
Total	1,317
Covered Loans \| Commercial Loans \| Farmland Loan
Financing Receivable, Impaired [Line Items]
Total		301
Covered Loans \| Consumer Real Estate \| Home Equity Lines
Financing Receivable, Impaired [Line Items]
Total	204	232
Covered Loans \| Consumer Real Estate \| Single Family Owner Occupied
Financing Receivable, Impaired [Line Items]
Total	682	1,555
Covered Loans \| Consumer Real Estate \| Owner occupied construction
Financing Receivable, Impaired [Line Items]
Total	$ 106	$ 190

Nonaccrual Loans by Loan Class (Detail) (USD $)
In Thousands, unless otherwise specified

Dec. 31, 2014

Dec. 31, 2013

Financing Receivable, Impaired [Line Items]

Total

$ 12,994

$ 22,506

Purchased impaired loans

Total nonaccrual loans

12,994

22,514

Commercial Loans | Construction Development And Other Land