Loans Modified as Troubled Debt Restructurings by Type of Concession Made and Loan Class (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014 Contract	Sep. 30, 2013 Contract	Sep. 30, 2014 Contract	Sep. 30, 2013 Contract
Financing Receivable, Modifications [Line Items]
Total Contracts	6	3	12	3
Pre-Modification Recorded Investment	$ 2,267	$ 1,001	$ 3,353	$ 1,001
Post-Modification Recorded Investment	2,267	926	3,353	926
Below Market Interest Rate
Financing Receivable, Modifications [Line Items]
Total Contracts			5	1
Pre-Modification Recorded Investment			2,095	359
Post-Modification Recorded Investment			2,095	326
Below Market Interest Rate | Owner occupied construction
Financing Receivable, Modifications [Line Items]
Total Contracts			1
Pre-Modification Recorded Investment			245
Post-Modification Recorded Investment			245
Below Market Interest Rate | Single Family Owner Occupied
Financing Receivable, Modifications [Line Items]
Total Contracts	3	1	4	1
Pre-Modification Recorded Investment	1,715	359	1,850	359
Post-Modification Recorded Investment	1,715	326	1,850	326
Extended Payment Term
Financing Receivable, Modifications [Line Items]
Total Contracts			2
Pre-Modification Recorded Investment			771
Post-Modification Recorded Investment			771
Extended Payment Term | Non-farm, Non-residential
Financing Receivable, Modifications [Line Items]
Total Contracts			1
Pre-Modification Recorded Investment			303
Post-Modification Recorded Investment			303
Extended Payment Term | Single-family Non-owner Occupied
Financing Receivable, Modifications [Line Items]
Total Contracts	1		1
Pre-Modification Recorded Investment	468		468
Post-Modification Recorded Investment	468		468
Below Market Interest Rate And Extended Payment Term | Single Family Owner Occupied
Financing Receivable, Modifications [Line Items]
Total Contracts	2	2	5	2
Pre-Modification Recorded Investment	84	642	487	642
Post-Modification Recorded Investment	$ 84	$ 600	$ 487	$ 600