Loans - Summary of Loans Secured by Commercial Real Estate (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Financing Receivable, Recorded Investment, Past Due [Line Items]
Commercial real estate included in commercial loans held for sale	$ (7,088)	$ (14,178)
Loans, gross	733,940	773,558
Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Commercial real estate included in gross loans	451,384
Commercial real estate included in commercial loans held for sale	6,938
Loans, gross	458,322
Percentage of gross loans and commercial loans held for sale	61.80%
Percentage of regulatory capital	408.30%
Construction, land development, and other land loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, gross	70,540	87,613
Construction, land development, and other land loans [Member] \| Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Commercial real estate included in gross loans	70,540
Commercial real estate included in commercial loans held for sale	2,113
Loans, gross	72,653
Percentage of gross loans and commercial loans held for sale	9.80%
Percentage of regulatory capital	64.70%
Multifamily residential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, gross	12,547	17,945
Multifamily residential [Member] \| Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Commercial real estate included in gross loans	12,547
Loans, gross	12,547
Percentage of gross loans and commercial loans held for sale	1.70%
Percentage of regulatory capital	11.20%
Nonfarm nonresidential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans, gross	368,297	373,018
Nonfarm nonresidential [Member] \| Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Commercial real estate included in gross loans	368,297
Commercial real estate included in commercial loans held for sale	4,825
Loans, gross	$ 373,122
Percentage of gross loans and commercial loans held for sale	50.30%
Percentage of regulatory capital	332.40%

Amount before allowance of commercial loans issued to businesses to acquire, develop, construct, improve, or refinance land or building. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans covered under loss sharing agreements.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 7

-Subparagraph a

-Article 9

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.7(a))

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=7512638&loc=d3e5066-111524

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.1(c))

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Statement of Position (SOP)

-Number 01-6

-Paragraph 13

-Subparagraph e

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 60

-Paragraph 47

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Audit and Accounting Guide (AAG)

-Number AAG-DEP

-Paragraph 51, 52, 53

-IssueDate 2006-05-01

-Chapter 8

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details