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	Dec. 31, 2012	Dec. 31, 2011
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	$ 738,282	$ 773,558
Less: other loans held for sale	(776)	(14,178)
Construction, land development, and other land loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	66,123	87,613
Construction, land development, and other land loans [Member] | Grade 3 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	10,384	8,295
Construction, land development, and other land loans [Member] | Grade 4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	22,384	13,601
Construction, land development, and other land loans [Member] | Grade W [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	6,735	9,075
Construction, land development, and other land loans [Member] | Grade 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	3,354	3,671
Construction, land development, and other land loans [Member] | Grade 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	4,000	21,511
Construction, land development, and other land loans [Member] | Grade 7 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	2,780	10,624
Construction, land development, and other land loans [Member] | Not Risk Rated [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	16,486	20,836
Multifamily residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	11,659	17,945
Multifamily residential [Member] | Grade 3 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	404	3,252
Multifamily residential [Member] | Grade 4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	1,391	945
Multifamily residential [Member] | Grade W [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	2,431	4,233
Multifamily residential [Member] | Grade 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	7,183	7,550
Multifamily residential [Member] | Grade 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	246	1,956
Multifamily residential [Member] | Not Risk Rated [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	4	9
Nonfarm nonresidential [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	380,654	373,018
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		457
Nonfarm nonresidential [Member] | Grade 3 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	83,554	100,265
Nonfarm nonresidential [Member] | Grade 4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	151,956	126,961
Nonfarm nonresidential [Member] | Grade W [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	73,306	51,889
Nonfarm nonresidential [Member] | Grade 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	28,910	27,235
Nonfarm nonresidential [Member] | Grade 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	38,328	61,907
Nonfarm nonresidential [Member] | Grade 7 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	1,801	3,991
Nonfarm nonresidential [Member] | Not Risk Rated [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	156	313
Other Loans Held for Sale [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	776	14,178
Other Loans Held for Sale [Member] | Grade 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans		8,800
Other Loans Held for Sale [Member] | Grade 7 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	776	5,378
Total commercial real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	459,212	492,754
Less: other loans held for sale	(776)	(14,178)
Commercial real estate included in gross loans	458,436	478,576
Total commercial real estate [Member] | Grade 1 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	2,643
Total commercial real estate [Member] | Grade 2 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans		457
Total commercial real estate [Member] | Grade 3 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	94,342	111,812
Total commercial real estate [Member] | Grade 4 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	175,731	141,507
Total commercial real estate [Member] | Grade W [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	82,472	65,197
Total commercial real estate [Member] | Grade 5 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	39,447	38,456
Total commercial real estate [Member] | Grade 6 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	42,574	94,174
Total commercial real estate [Member] | Grade 7 [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	5,357	19,993
Total commercial real estate [Member] | Not Risk Rated [Member]
Financing Receivable, Recorded Investment [Line Items]
Gross Loans	$ 16,646	$ 21,158