Recorded Investment in Loans Considered to Be Impaired and Related Information on Impaired Loans (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011
Financing Receivable, Recorded Investment [Line Items]
Impaired loans with no related allowance, Recorded Investment	$ 9,418	$ 6,935
Impaired loans with a related allowance, Recorded Investment	13,784	17,221
Total impaired loans, Recorded Investment	23,202	24,156
Impaired loans with no related allowance, Unpaid Principal balance	9,906	7,107
Impaired loans with a related allowance, Unpaid Principal Balance	19,450	17,505
Total impaired loans, Unpaid Principal Balance	29,356	24,612
Impaired loans with no related allowance, Related Allowance
Impaired loans with a related allowance, Related Allowance	5,593	5,198
Total impaired loans, Related Allowance	5,593	5,198
Impaired loans with no related allowance, Average Recorded Investment	10,397	11,038
Impaired loans with a related allowance, Average Recorded Investment	16,780	15,496
Total impaired loans, Average Recorded Investment	27,177	26,534
Impaired loans with no related allowance, Interest Income Recognized	323	155
Impaired loans with a related allowance, Interest Income Recognized	1,453	492
Total impaired loans, Interest Income Recognized	1,776	647
Commercial Loans \| Construction Development And Other Land
Financing Receivable, Recorded Investment [Line Items]
Impaired loans with no related allowance, Recorded Investment	2,916	661
Impaired loans with a related allowance, Recorded Investment		112
Impaired loans with no related allowance, Unpaid Principal balance	2,916	661
Impaired loans with a related allowance, Unpaid Principal Balance		112
Impaired loans with no related allowance, Related Allowance
Impaired loans with a related allowance, Related Allowance		4
Impaired loans with no related allowance, Average Recorded Investment	935	1,341
Impaired loans with a related allowance, Average Recorded Investment	69	248
Impaired loans with no related allowance, Interest Income Recognized	3
Impaired loans with a related allowance, Interest Income Recognized	1	9
Commercial Loans \| Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Impaired loans with no related allowance, Recorded Investment	284	114
Impaired loans with a related allowance, Recorded Investment	3,318	4,031
Impaired loans with no related allowance, Unpaid Principal balance	284	127
Impaired loans with a related allowance, Unpaid Principal Balance	8,502	4,069
Impaired loans with no related allowance, Related Allowance
Impaired loans with a related allowance, Related Allowance	3,192	2,048
Impaired loans with no related allowance, Average Recorded Investment	320	2,251
Impaired loans with a related allowance, Average Recorded Investment	4,510	2,358
Impaired loans with no related allowance, Interest Income Recognized	17	4
Impaired loans with a related allowance, Interest Income Recognized	948	21
Commercial Loans \| Multi-family Residential
Financing Receivable, Recorded Investment [Line Items]
Impaired loans with no related allowance, Recorded Investment		278
Impaired loans with a related allowance, Recorded Investment	378
Impaired loans with no related allowance, Unpaid Principal balance		278
Impaired loans with a related allowance, Unpaid Principal Balance	397
Impaired loans with no related allowance, Related Allowance
Impaired loans with a related allowance, Related Allowance	18
Impaired loans with no related allowance, Average Recorded Investment	517	1,177
Impaired loans with a related allowance, Average Recorded Investment	143	470
Impaired loans with no related allowance, Interest Income Recognized	4	24
Impaired loans with a related allowance, Interest Income Recognized	3
Commercial Loans \| Single-family Non-owner Occupied
Financing Receivable, Recorded Investment [Line Items]
Impaired loans with no related allowance, Recorded Investment	383	1,206
Impaired loans with a related allowance, Recorded Investment	2,411	2,232
Impaired loans with no related allowance, Unpaid Principal balance	684	1,244
Impaired loans with a related allowance, Unpaid Principal Balance	2,460	2,232
Impaired loans with no related allowance, Related Allowance
Impaired loans with a related allowance, Related Allowance	996	124
Impaired loans with no related allowance, Average Recorded Investment	1,101	1,659
Impaired loans with a related allowance, Average Recorded Investment	2,484	2,323
Impaired loans with no related allowance, Interest Income Recognized	56	39
Impaired loans with a related allowance, Interest Income Recognized	80	107
Commercial Loans \| Non-farm, Non-residential
Financing Receivable, Recorded Investment [Line Items]
Impaired loans with no related allowance, Recorded Investment	5,282	1,616
Impaired loans with a related allowance, Recorded Investment	2,781	5,317
Impaired loans with no related allowance, Unpaid Principal balance	5,362	1,647
Impaired loans with a related allowance, Unpaid Principal Balance	2,958	5,480
Impaired loans with no related allowance, Related Allowance
Impaired loans with a related allowance, Related Allowance	358	1,819
Impaired loans with no related allowance, Average Recorded Investment	2,619	2,059
Impaired loans with a related allowance, Average Recorded Investment	5,820	4,112
Impaired loans with no related allowance, Interest Income Recognized	102	25
Impaired loans with a related allowance, Interest Income Recognized	317	191
Commercial Loans \| Agricultural
Financing Receivable, Recorded Investment [Line Items]
Impaired loans with no related allowance, Related Allowance
Commercial Loans \| Farmland Loan
Financing Receivable, Recorded Investment [Line Items]
Impaired loans with no related allowance, Recorded Investment		258
Impaired loans with no related allowance, Unpaid Principal balance		258
Impaired loans with no related allowance, Related Allowance
Impaired loans with no related allowance, Average Recorded Investment	93	167
Impaired loans with a related allowance, Average Recorded Investment	93	83
Consumer Real Estate \| Home Equity Lines
Financing Receivable, Recorded Investment [Line Items]
Impaired loans with no related allowance, Recorded Investment	276	368
Impaired loans with a related allowance, Recorded Investment	223
Impaired loans with no related allowance, Unpaid Principal balance	277	378
Impaired loans with a related allowance, Unpaid Principal Balance	230
Impaired loans with no related allowance, Related Allowance
Impaired loans with a related allowance, Related Allowance	223
Impaired loans with no related allowance, Average Recorded Investment	370	476
Impaired loans with a related allowance, Average Recorded Investment	150	108
Impaired loans with no related allowance, Interest Income Recognized	28	15
Impaired loans with a related allowance, Interest Income Recognized	1
Consumer Real Estate \| Single Family Owner Occupied
Financing Receivable, Recorded Investment [Line Items]
Impaired loans with no related allowance, Recorded Investment	277	2,428
Impaired loans with a related allowance, Recorded Investment	4,673	5,529
Impaired loans with no related allowance, Unpaid Principal balance	383	2,508
Impaired loans with a related allowance, Unpaid Principal Balance	4,903	5,612
Impaired loans with no related allowance, Related Allowance
Impaired loans with a related allowance, Related Allowance	806	1,203
Impaired loans with no related allowance, Average Recorded Investment	4,441	1,825
Impaired loans with a related allowance, Average Recorded Investment	3,511	5,794
Impaired loans with no related allowance, Interest Income Recognized	113	43
Impaired loans with a related allowance, Interest Income Recognized	103	164
Consumer Real Estate \| Owner occupied construction
Financing Receivable, Recorded Investment [Line Items]
Impaired loans with no related allowance, Related Allowance
Impaired loans with no related allowance, Average Recorded Investment		60
Impaired loans with no related allowance, Interest Income Recognized		3
Consumer and Other \| Consumer Loan
Financing Receivable, Recorded Investment [Line Items]
Impaired loans with no related allowance, Recorded Investment		6
Impaired loans with no related allowance, Unpaid Principal balance		6
Impaired loans with no related allowance, Related Allowance
Impaired loans with no related allowance, Average Recorded Investment	1	23
Impaired loans with no related allowance, Interest Income Recognized		$ 2

Impaired loans with no related investment, related allowance.

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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=7512638&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=7512638&loc=d3e5258-111524

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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 14A

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=7512638&loc=SL6953550-111524

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