Loans and Allowance for Loan Losses - Schedule of Number of Loans Modified Troubled Debt Restructuring by Loan Portfolio (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
Mar. 31, 2015 SecurityLoan	Dec. 31, 2014 SecurityLoan
Financing Receivable, Modifications [Line Items]
Number of Loans	15	18
Pre-Modification Outstanding Principal Balance	$ 3,947	$ 5,089
Post-Modification Principal Balance	3,200	3,929
Subsequent default number of loans	2	2
Recorded Investment	886	886
Real Estate [Member] \| Construction, Land Development and Other Land Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	3	4
Pre-Modification Outstanding Principal Balance	2,220	3,282
Post-Modification Principal Balance	1,756	2,365
Real Estate [Member] \| Secured by 1-4 Family Residential Properties [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	4	4
Pre-Modification Outstanding Principal Balance	200	200
Post-Modification Principal Balance	152	156
Real Estate [Member] \| Secured by Non-farm, Non-residential Properties [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	5	6
Pre-Modification Outstanding Principal Balance	1,368	1,448
Post-Modification Principal Balance	1,189	1,299
Subsequent default number of loans	2	2
Recorded Investment	886	886
Commercial and Industrial Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	3	4
Pre-Modification Outstanding Principal Balance	159	159
Post-Modification Principal Balance	$ 103	$ 109

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Number of financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 33

-URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953676-111524

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Pre-modification amount of investment in financing receivables modified by troubled debt restructurings.

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Number of financing receivables that have been modified by troubled debt restructurings within the previous 12 months and for which there was a payment default.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 34

-URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953682-111524

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