Loans - Summary of Company's Internal Credit Quality Indicators on Gross Loans and Commercial Loans Held for Sale (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	$ 731,540	$ 739,058
Less: other loans held for sale	(776)	(776)
Total commercial real estate loans	730,764	738,282	761,687
Construction, land development, and other land loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	68,008	66,123
Construction, land development, and other land loans [Member] | Grade 1 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans
Construction, land development, and other land loans [Member] | Grade 2 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans
Construction, land development, and other land loans [Member] | Grade 3 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	8,060	10,384
Construction, land development, and other land loans [Member] | Grade 4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	28,446	22,384
Construction, land development, and other land loans [Member] | Grade W [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	6,627	6,735
Construction, land development, and other land loans [Member] | Grade 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	3,290	3,354
Construction, land development, and other land loans [Member] | Grade 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	3,514	4,000
Construction, land development, and other land loans [Member] | Grade 7 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	2,726	2,780
Construction, land development, and other land loans [Member] | Not Risk Rated [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	15,345	16,486
Multifamily residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	11,555	11,659
Multifamily residential [Member] | Grade 1 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans
Multifamily residential [Member] | Grade 2 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans
Multifamily residential [Member] | Grade 3 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	394	404
Multifamily residential [Member] | Grade 4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	1,482	1,391
Multifamily residential [Member] | Grade W [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	2,390	2,431
Multifamily residential [Member] | Grade 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	7,088	7,183
Multifamily residential [Member] | Grade 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	184	246
Multifamily residential [Member] | Grade 7 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans
Multifamily residential [Member] | Not Risk Rated [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	17	4
Nonfarm nonresidential [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	376,447	380,654
Nonfarm nonresidential [Member] | Grade 1 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans		2,643
Nonfarm nonresidential [Member] | Grade 2 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans
Nonfarm nonresidential [Member] | Grade 3 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	77,466	83,554
Nonfarm nonresidential [Member] | Grade 4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	159,702	151,956
Nonfarm nonresidential [Member] | Grade W [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	71,865	73,306
Nonfarm nonresidential [Member] | Grade 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	26,083	28,910
Nonfarm nonresidential [Member] | Grade 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	38,976	38,328
Nonfarm nonresidential [Member] | Grade 7 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	1,798	1,801
Nonfarm nonresidential [Member] | Not Risk Rated [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	557	156
Commercial real estate in other loans held for sale [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	776	776
Commercial real estate in other loans held for sale [Member] | Grade 1 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans
Commercial real estate in other loans held for sale [Member] | Grade 2 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans
Commercial real estate in other loans held for sale [Member] | Grade 3 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans
Commercial real estate in other loans held for sale [Member] | Grade 4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans
Commercial real estate in other loans held for sale [Member] | Grade W [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans
Commercial real estate in other loans held for sale [Member] | Grade 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans
Commercial real estate in other loans held for sale [Member] | Grade 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans
Commercial real estate in other loans held for sale [Member] | Grade 7 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	776	776
Commercial real estate in other loans held for sale [Member] | Not Risk Rated [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans
Commercial real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	456,786	459,212
Less: other loans held for sale	(776)	(776)
Total commercial real estate loans	456,010	458,436	470,891
Commercial real estate [Member] | Grade 1 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans		2,643
Commercial real estate [Member] | Grade 2 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans
Commercial real estate [Member] | Grade 3 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	85,920	94,342
Commercial real estate [Member] | Grade 4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	189,630	175,731
Commercial real estate [Member] | Grade W [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	80,882	82,472
Commercial real estate [Member] | Grade 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	36,461	39,447
Commercial real estate [Member] | Grade 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	42,674	42,574
Commercial real estate [Member] | Grade 7 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	5,300	5,357
Commercial real estate [Member] | Not Risk Rated [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	$ 15,919	$ 16,646