Average Recorded Investment and Interest Income Recognized on Impaired Loans Excluding Purchased Credit Impaired Loans (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Financing Receivable, Recorded Investment [Line Items]
Impaired loans with no related allowance, Average Recorded Investment	$ 10,430	$ 18,893	$ 9,458	$ 17,859
Impaired loans with a related allowance, Average Recorded Investment	12,851	12,390	16,584	13,046
Total impaired loans, Average Recorded Investment	23,281	31,283	26,042	30,905
Impaired loans with no related allowance, Interest Income Recognized	17	43	188	809
Impaired loans with a related allowance, Interest Income Recognized	16	33	146	230
Total impaired loans, Interest Income Recognized	33	76	334	1,039
Commercial Loans \| Construction Development And Other Land
Financing Receivable, Recorded Investment [Line Items]
Impaired loans with no related allowance, Average Recorded Investment		6,375		5,133
Impaired loans with a related allowance, Average Recorded Investment		463		1,409
Impaired loans with no related allowance, Interest Income Recognized		40		294
Impaired loans with a related allowance, Interest Income Recognized				117
Commercial Loans \| Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Impaired loans with no related allowance, Average Recorded Investment	1,258		614	834
Impaired loans with a related allowance, Average Recorded Investment		5,328	2,932	4,009
Impaired loans with no related allowance, Interest Income Recognized			17	11
Impaired loans with a related allowance, Interest Income Recognized		11	47	11
Commercial Loans \| Multi-family Residential
Financing Receivable, Recorded Investment [Line Items]
Impaired loans with no related allowance, Average Recorded Investment				24
Impaired loans with a related allowance, Average Recorded Investment	5,568		5,586	126
Impaired loans with no related allowance, Interest Income Recognized				3
Impaired loans with a related allowance, Interest Income Recognized	1		23	7
Commercial Loans \| Single-family Non-owner Occupied
Financing Receivable, Recorded Investment [Line Items]
Impaired loans with no related allowance, Average Recorded Investment	321	317	247	1,146
Impaired loans with a related allowance, Average Recorded Investment	369	365	370	1,064
Impaired loans with no related allowance, Interest Income Recognized	7		8	93
Impaired loans with a related allowance, Interest Income Recognized	1		2	12
Commercial Loans \| Non-farm, Non-residential
Financing Receivable, Recorded Investment [Line Items]
Impaired loans with no related allowance, Average Recorded Investment	5,971	8,194	6,089	7,739
Impaired loans with a related allowance, Average Recorded Investment	4,386	606	4,404	1,791
Impaired loans with no related allowance, Interest Income Recognized			89	296
Impaired loans with a related allowance, Interest Income Recognized	6		31	26
Commercial Loans \| Farmland Loan
Financing Receivable, Recorded Investment [Line Items]
Impaired loans with no related allowance, Average Recorded Investment		667	241	372
Impaired loans with no related allowance, Interest Income Recognized		3	11	12
Consumer Real Estate \| Home Equity Lines
Financing Receivable, Recorded Investment [Line Items]
Impaired loans with no related allowance, Average Recorded Investment		546	88	518
Impaired loans with a related allowance, Average Recorded Investment		535	76	329
Impaired loans with no related allowance, Interest Income Recognized			2	25
Impaired loans with a related allowance, Interest Income Recognized		9	1	3
Consumer Real Estate \| Single Family Owner Occupied
Financing Receivable, Recorded Investment [Line Items]
Impaired loans with no related allowance, Average Recorded Investment	2,880	2,794	2,179	2,069
Impaired loans with a related allowance, Average Recorded Investment	2,528	5,093	3,216	4,318
Impaired loans with no related allowance, Interest Income Recognized	10		61	70
Impaired loans with a related allowance, Interest Income Recognized	8	13	42	54
Consumer Real Estate \| Owner occupied construction
Financing Receivable, Recorded Investment [Line Items]
Impaired loans with no related allowance, Average Recorded Investment				20
Impaired loans with no related allowance, Interest Income Recognized				5
Consumer and Other \| Consumer Loan
Financing Receivable, Recorded Investment [Line Items]
Impaired loans with no related allowance, Average Recorded Investment				$ 4

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Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 15

-Subparagraph (c)(1)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5212-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 17

-URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5258-111524

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