Condensed Statements of Cash Flows (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating activities
Net income	$ 25,490us-gaap_NetIncomeLoss	$ 23,312us-gaap_NetIncomeLoss	$ 28,577us-gaap_NetIncomeLoss
Adjustments to reconcile net income to net cash provided by operating activities:
Net cash provided by operating activities	41,689	44,518	56,639
Investing activities
Proceeds from sales of securities available-for-sale	162,443	105,934	155,600
Payments to acquire securities available-for-sale	(6,047)	(201,138)	(245,344)
Net cash provided by (used in) investing activities	280,955	(1,167)	252,474
Financing activities
Proceeds from stock options exercised	53	85	144
Payments for repurchase of treasury stock	(2,168)	(28,421)	(1,012)
Payments of common dividends	(9,200)us-gaap_PaymentsOfDividendsCommonStock	(9,475)us-gaap_PaymentsOfDividendsCommonStock	(8,162)us-gaap_PaymentsOfDividendsCommonStock
Payments of preferred dividends	(910)	(992)	(1,120)
Net cash used in financing activities	(141,551)	(131,631)	(211,560)
Net increase (decrease) in cash and cash equivalents	181,093	(88,280)	97,553
Cash and cash equivalents at beginning of period	56,567	144,847	47,294
Cash and cash equivalents at end of period	237,660	56,567	144,847
First Community Bancshares, Inc.
Operating activities
Net income	25,490	23,312	28,577
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in undistributed earnings of subsidiary	(12,109)	20,035	(21,400)
Loss (gain) on sale of securities	2	(193)	(49)
Decrease (increase) in other assets	4,624	(5,293)	123
(Decrease) increase in other liabilities	(347)	333	588
Increase in other operating activities	(65)	(106)	(58)
Net cash provided by operating activities	17,595	38,088	7,781
Investing activities
Proceeds from sales of securities available-for-sale	5,030	3,380	2,151
Payments to acquire securities available-for-sale		(5,000)	(5,137)
Investment in subsidiary	(2,000)
Net cash provided by (used in) investing activities	3,030	(1,620)	(2,986)
Financing activities
Proceeds from other borrowings	2,000
Proceeds from stock options exercised	89	789	144
Payments for repurchase of treasury stock	(2,168)	(28,421)	(1,012)
Payments of common dividends	(9,200)	(9,476)	(8,162)
Payments of preferred dividends	(910)	(992)	(1,120)
Proceeds from other financing activities	338	28	137
Net cash used in financing activities	(9,851)	(38,072)	(10,013)
Net increase (decrease) in cash and cash equivalents	10,774	(1,604)	(5,218)
Cash and cash equivalents at beginning of period	10,872	12,476	17,694
Cash and cash equivalents at end of period	$ 21,646	$ 10,872	$ 12,476

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