Average Recorded Investment and Interest Income Recognized on Impaired Loans Excluding Purchased Credit Impaired Loans (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Financing Receivable, Recorded Investment [Line Items]
Impaired loans with no related allowance, Recorded Investment	$ 9,361	$ 11,184
Impaired loans with a related allowance, Recorded Investment	11,012	11,534
Total impaired loans, Recorded Investment	20,373	22,718
Impaired loans with no related allowance, Unpaid Principal balance	9,419	11,277
Impaired loans with a related allowance, Unpaid Principal Balance	11,084	11,558
Total impaired loans, Unpaid Principal Balance	20,503	22,835
Impaired loans with no related allowance, Related Allowance	0	0
Impaired loans with a related allowance, Related Allowance	2,321	2,371
Total impaired loans, Related Allowance	2,321	2,371
Commercial Loans \| Single-family Non-owner Occupied
Financing Receivable, Recorded Investment [Line Items]
Impaired loans with no related allowance, Recorded Investment	781	782
Impaired loans with a related allowance, Recorded Investment	356	619
Impaired loans with no related allowance, Unpaid Principal balance	782	783
Impaired loans with a related allowance, Unpaid Principal Balance	356	623
Impaired loans with no related allowance, Related Allowance	0	0
Impaired loans with a related allowance, Related Allowance	18	124
Commercial Loans \| Non-farm, Non-residential
Financing Receivable, Recorded Investment [Line Items]
Impaired loans with no related allowance, Recorded Investment	7,983	8,427
Impaired loans with a related allowance, Recorded Investment	5,348	5,667
Impaired loans with no related allowance, Unpaid Principal balance	7,983	8,427
Impaired loans with a related allowance, Unpaid Principal Balance	5,361	5,673
Impaired loans with no related allowance, Related Allowance	0	0
Impaired loans with a related allowance, Related Allowance	1,529	1,568
Consumer Real Estate \| Single Family Owner Occupied
Financing Receivable, Recorded Investment [Line Items]
Impaired loans with no related allowance, Recorded Investment	597	1,975
Impaired loans with a related allowance, Recorded Investment	4,962	4,899
Impaired loans with no related allowance, Unpaid Principal balance	654	2,067
Impaired loans with a related allowance, Unpaid Principal Balance	5,013	4,907
Impaired loans with no related allowance, Related Allowance	0	0
Impaired loans with a related allowance, Related Allowance	771	672
Consumer Real Estate \| Owner Occupied Construction
Financing Receivable, Recorded Investment [Line Items]
Impaired loans with a related allowance, Recorded Investment	346	349
Impaired loans with a related allowance, Unpaid Principal Balance	354	355
Impaired loans with a related allowance, Related Allowance	$ 3	$ 7

Impaired loans with no related investment, related allowance.

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Impaired loans with a related investment, related allowance.

+ References

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+ References

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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 14A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=49124121&loc=SL6953550-111524

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Amount of allowance for credit losses related to recorded investment.

+ 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 (a)(3)
-URI http://asc.fasb.org/extlink&oid=49124121&loc=d3e5212-111524

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+ 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 (a)(4)
-URI http://asc.fasb.org/extlink&oid=49124121&loc=d3e5212-111524

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
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-URI http://asc.fasb.org/extlink&oid=49124121&loc=d3e5212-111524

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+ 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 (a)(4)
-URI http://asc.fasb.org/extlink&oid=49124121&loc=d3e5212-111524

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