Company's and Bank's Capital Ratios (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
First Community Bancshares, Inc.
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital to Risk-Weighted Assets, actual amount	$ 270,636	$ 282,729
Tier 1 Capital to Risk-Weighted Assets, actual amount	250,012	261,467
Tier 1 Capital to Average Assets (Leverage), actual amount	250,012	261,467
Total Capital to Risk-Weighted Assets, actual (ratio)	16.44%	16.70%
Tier 1 Capital to Risk-Weighted Assets, actual (ratio)	15.19%	15.44%
Tier 1 Capital to Average Assets (Leverage), actual (ratio)	9.95%	9.96%
Total Capital to Risk-Weighted Assets, for capital adequacy purposes amount	131,694	135,441
Tier 1 Capital to Risk-Weighted Assets, for capital adequacy purposes amount	65,847	67,720
Tier 1 Capital to Average Assets (Leverage), for capital adequacy purposes amount	100,489	104,974
Total Capital to Risk-Weighted Assets, for capital adequacy purposes (ratio)	8.00%	8.00%
Tier 1 Capital to Risk-Weighted Assets, for capital adequacy purposes (ratio)	4.00%	4.00%
Tier 1 Capital to Average Assets (Leverage), for capital adequacy purposes (ratio)	4.00%	4.00%
First Community Bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital to Risk-Weighted Assets, actual amount	236,699	255,219
Tier 1 Capital to Risk-Weighted Assets, actual amount	216,314	234,226
Tier 1 Capital to Average Assets (Leverage), actual amount	216,314	234,226
Total Capital to Risk-Weighted Assets, actual (ratio)	14.55%	15.23%
Tier 1 Capital to Risk-Weighted Assets, actual (ratio)	13.30%	13.97%
Tier 1 Capital to Average Assets (Leverage), actual (ratio)	8.63%	8.98%
Total Capital to Risk-Weighted Assets, for capital adequacy purposes amount	130,141	134,087
Tier 1 Capital to Risk-Weighted Assets, for capital adequacy purposes amount	65,070	67,043
Tier 1 Capital to Average Assets (Leverage), for capital adequacy purposes amount	100,219	104,304
Total Capital to Risk-Weighted Assets, for capital adequacy purposes (ratio)	8.00%	8.00%
Tier 1 Capital to Risk-Weighted Assets, for capital adequacy purposes (ratio)	4.00%	4.00%
Tier 1 Capital to Average Assets (Leverage), for capital adequacy purposes (ratio)	4.00%	4.00%
Total Capital to Risk-Weighted Assets, to be well capitalized under prompt corrective action provision amount	162,676	167,609
Tier 1 Capital to Risk-Weighted Assets, to be well capitalized under prompt corrective action provision amount	97,606	100,565
Tier 1 Capital to Average Assets (Leverage), to be well capitalized under prompt corrective action provision amount	$ 125,274	$ 130,381
Total Capital to Risk-Weighted Assets, to be well capitalized under prompt corrective action provision (ratio)	10.00%	10.00%
Tier 1 Capital to Risk-Weighted Assets, to be well capitalized under prompt corrective action provision (ratio)	6.00%	6.00%
Tier 1 Capital to Average Assets (Leverage), to be well capitalized under prompt corrective action provision (ratio)	5.00%	5.00%