Recorded Investment In Loans Considered To Be Impaired And Related Information On Impaired Loans (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Financing Receivable, Recorded Investment [Line Items]
Impaired loans with no related allowance, Recorded Investment	$ 11,697		$ 9,418
Impaired loans with a related allowance, Recorded Investment	17,116		13,784
Total impaired loans, Recorded Investment	28,813		23,202
Impaired loans with no related allowance, Unpaid Principal balance	14,292		9,906
Impaired loans with a related allowance, Unpaid Principal Balance	22,801		19,450
Total impaired loans, Unpaid Principal Balance	37,093		29,356
Impaired loans with no related allowance, Related Allowance
Impaired loans with a related allowance, Related Allowance	6,401		5,593
Total impaired loans, Related Allowance	6,401		5,593
Impaired loans with no related allowance, Average Recorded Investment	10,558	12,996
Impaired loans with a related allowance, Average Recorded Investment	15,454	15,544
Total impaired loans, Average Recorded Investment	26,012	28,540
Impaired loans with no related allowance, Interest Income Recognized	451	46
Impaired loans with a related allowance, Interest Income Recognized	193	148
Total impaired loans, Interest Income Recognized	644	194
Commercial Loans \| Construction Development And Other Land
Financing Receivable, Recorded Investment [Line Items]
Impaired loans with no related allowance, Recorded Investment	1,473		2,916
Impaired loans with a related allowance, Recorded Investment	5,339
Impaired loans with no related allowance, Unpaid Principal balance	1,675		2,916
Impaired loans with a related allowance, Unpaid Principal Balance	5,356
Impaired loans with no related allowance, Related Allowance
Impaired loans with a related allowance, Related Allowance	1,822
Impaired loans with no related allowance, Average Recorded Investment	2,195	30
Impaired loans with a related allowance, Average Recorded Investment	2,670	111
Impaired loans with no related allowance, Interest Income Recognized	43
Impaired loans with a related allowance, Interest Income Recognized	117	1
Commercial Loans \| Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Impaired loans with no related allowance, Recorded Investment	913		284
Impaired loans with a related allowance, Recorded Investment	3,108		3,318
Impaired loans with no related allowance, Unpaid Principal balance	912		284
Impaired loans with a related allowance, Unpaid Principal Balance	8,236		8,502
Impaired loans with no related allowance, Related Allowance
Impaired loans with a related allowance, Related Allowance	3,100		3,192
Impaired loans with no related allowance, Average Recorded Investment	599	483
Impaired loans with a related allowance, Average Recorded Investment	3,217	2,210
Impaired loans with no related allowance, Interest Income Recognized	11
Commercial Loans \| Multi-family Residential
Financing Receivable, Recorded Investment [Line Items]
Impaired loans with no related allowance, Recorded Investment	70
Impaired loans with a related allowance, Recorded Investment	375		378
Impaired loans with no related allowance, Unpaid Principal balance	87
Impaired loans with a related allowance, Unpaid Principal Balance	396		397
Impaired loans with no related allowance, Related Allowance
Impaired loans with a related allowance, Related Allowance	15		18
Impaired loans with no related allowance, Average Recorded Investment	35	596
Impaired loans with a related allowance, Average Recorded Investment	376
Impaired loans with no related allowance, Interest Income Recognized	2
Impaired loans with a related allowance, Interest Income Recognized	7
Commercial Loans \| Single-family Non-owner Occupied
Financing Receivable, Recorded Investment [Line Items]
Impaired loans with no related allowance, Recorded Investment	1,299		383
Impaired loans with a related allowance, Recorded Investment	1,046		2,411
Impaired loans with no related allowance, Unpaid Principal balance	2,301		684
Impaired loans with a related allowance, Unpaid Principal Balance	1,107		2,460
Impaired loans with no related allowance, Related Allowance
Impaired loans with a related allowance, Related Allowance	204		996
Impaired loans with no related allowance, Average Recorded Investment	841	1,514
Impaired loans with a related allowance, Average Recorded Investment	1,728	2,541
Impaired loans with no related allowance, Interest Income Recognized	79	9
Impaired loans with a related allowance, Interest Income Recognized	3	31
Commercial Loans \| Non-farm, Non-residential
Financing Receivable, Recorded Investment [Line Items]
Impaired loans with no related allowance, Recorded Investment	6,628		5,282
Impaired loans with a related allowance, Recorded Investment	2,730		2,781
Impaired loans with no related allowance, Unpaid Principal balance	7,227		5,362
Impaired loans with a related allowance, Unpaid Principal Balance	2,926		2,958
Impaired loans with no related allowance, Related Allowance
Impaired loans with a related allowance, Related Allowance	430		358
Impaired loans with no related allowance, Average Recorded Investment	5,955	2,684
Impaired loans with a related allowance, Average Recorded Investment	2,756	7,310
Impaired loans with no related allowance, Interest Income Recognized	212	10
Impaired loans with a related allowance, Interest Income Recognized	26	91
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	177
Impaired loans with no related allowance, Unpaid Principal balance	197
Impaired loans with no related allowance, Related Allowance
Impaired loans with no related allowance, Average Recorded Investment	88
Impaired loans with no related allowance, Interest Income Recognized	9
Consumer Real Estate \| Home Equity Lines
Financing Receivable, Recorded Investment [Line Items]
Impaired loans with no related allowance, Recorded Investment	321		276
Impaired loans with a related allowance, Recorded Investment	222		223
Impaired loans with no related allowance, Unpaid Principal balance	444		277
Impaired loans with a related allowance, Unpaid Principal Balance	230		230
Impaired loans with no related allowance, Related Allowance
Impaired loans with a related allowance, Related Allowance	222		223
Impaired loans with no related allowance, Average Recorded Investment	298	502
Impaired loans with a related allowance, Average Recorded Investment	222
Impaired loans with no related allowance, Interest Income Recognized	25	6
Impaired loans with a related allowance, Interest Income Recognized	3
Consumer Real Estate \| Single Family Owner Occupied
Financing Receivable, Recorded Investment [Line Items]
Impaired loans with no related allowance, Recorded Investment	816		277
Impaired loans with a related allowance, Recorded Investment	4,296		4,673
Impaired loans with no related allowance, Unpaid Principal balance	1,449		383
Impaired loans with a related allowance, Unpaid Principal Balance	4,550		4,903
Impaired loans with no related allowance, Related Allowance
Impaired loans with a related allowance, Related Allowance	608		806
Impaired loans with no related allowance, Average Recorded Investment	547	7,185
Impaired loans with a related allowance, Average Recorded Investment	4,485	3,372
Impaired loans with no related allowance, Interest Income Recognized	70	21
Impaired loans with a related allowance, Interest Income Recognized	37	25
Consumer Real Estate \| Owner occupied construction
Financing Receivable, Recorded Investment [Line Items]
Impaired loans with no related allowance, Related Allowance
Consumer and Other \| Consumer Loan
Financing Receivable, Recorded Investment [Line Items]
Impaired loans with no related allowance, Related Allowance
Impaired loans with no related allowance, Average Recorded Investment		$ 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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