Loans - Summary of Delinquencies by Class (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012
Financing Receivable, Recorded Investment [Line Items]
Total loans, gross 30-89 days past due	$ 6,245	$ 7,580
Total loans, gross Greater than 90 days past due on nonaccrual	16,330	15,072
Total loans, gross past due	22,575	22,652
Total loans, gross Current	708,189	715,630
Total commercial real estate loans	730,764	738,282	761,687
30-89 days past due	6,245	7,580
Greater than 90 days past due on nonaccrual	17,106	15,848
Total past due	23,351	23,428
Current	708,189	715,630
Total loans	731,540	739,058
Commercial real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
30-89 days past due	2,978	4,994
Greater than 90 days past due on nonaccrual	9,546	9,199
Total past due	12,524	14,193
Current	444,262	445,019
Total loans	456,786	459,212
Total single family residential loans [Member]
Financing Receivable, Recorded Investment [Line Items]
30-89 days past due	2,287	1,785
Greater than 90 days past due on nonaccrual	4,944	5,557
Total past due	7,231	7,342
Current	159,158	160,838
Total loans	166,389	168,180
Total consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
30-89 days past due	315	405
Greater than 90 days past due on nonaccrual	364	264
Total past due	679	669
Current	48,372	49,905
Total loans	49,051	50,574
Other [Member]
Financing Receivable, Recorded Investment [Line Items]
30-89 days past due		1
Greater than 90 days past due on nonaccrual	1	2
Total past due	1	3
Current	9,693	9,428
Total loans	9,694	9,431
Other Loans Held for Sale [Member]
Financing Receivable, Recorded Investment [Line Items]
30-89 days past due
Greater than 90 days past due on nonaccrual	(776)	(776)
Total past due	(776)	(776)
Current
Total loans	(776)	(776)
Commercial Real Estate Other Receivable [Member] | Commercial real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
30-89 days past due	169	175
Greater than 90 days past due on nonaccrual	4,966	5,467
Total past due	5,135	5,642
Current	63,649	61,257
Total loans	68,784	66,899
Multifamily residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	11,555	11,659
Multifamily residential [Member] | Commercial real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
30-89 days past due		245
Greater than 90 days past due on nonaccrual	184
Total past due	184	245
Current	11,371	11,414
Total loans	11,555	11,659
Nonfarm nonresidential [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	376,447	380,654
Nonfarm nonresidential [Member] | Commercial real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
30-89 days past due	2,809	4,574
Greater than 90 days past due on nonaccrual	4,396	3,732
Total past due	7,205	8,306
Current	369,242	372,348
Total loans	376,447	380,654
Single family residential revolving open end loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial real estate loans	59,781	59,751
Single family residential revolving open end loans [Member] | Total single family residential loans [Member]
Financing Receivable, Recorded Investment [Line Items]
30-89 days past due	369	245
Greater than 90 days past due on nonaccrual	794	816
Total past due	1,163	1,061
Current	58,618	58,690
Total loans	59,781	59,751
Single family residential closed end, first lien [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial real estate loans	102,003	103,522
Single family residential closed end, first lien [Member] | Total single family residential loans [Member]
Financing Receivable, Recorded Investment [Line Items]
30-89 days past due	1,799	1,441
Greater than 90 days past due on nonaccrual	3,884	4,442
Total past due	5,683	5,883
Current	96,320	97,639
Total loans	102,003	103,522
Single family residential closed end junior lien [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial real estate loans	4,605	4,907
Single family residential closed end junior lien [Member] | Total single family residential loans [Member]
Financing Receivable, Recorded Investment [Line Items]
30-89 days past due	119	99
Greater than 90 days past due on nonaccrual	266	299
Total past due	385	398
Current	4,220	4,509
Total loans	4,605	4,907
Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial real estate loans	49,620		50,594
Commercial and Industrial [Member] | Total consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
30-89 days past due	665	395
Greater than 90 days past due on nonaccrual	2,251	826
Total past due	2,916	1,221
Current	46,704	50,440
Total loans	49,620	51,661
Credit cards [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial real estate loans	15	17
Credit cards [Member] | Total consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
30-89 days past due
Greater than 90 days past due on nonaccrual	15	17
Total past due	15	17
Current
Total loans	15	17
Consumer - other [Member]
Financing Receivable, Recorded Investment [Line Items]
Total commercial real estate loans	49,036	50,557
Consumer - other [Member] | Total consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
30-89 days past due	315	405
Greater than 90 days past due on nonaccrual	349	247
Total past due	664	652
Current	48,372	49,905
Total loans	49,036	50,557
Farmland [Member] | Other [Member]
Financing Receivable, Recorded Investment [Line Items]
30-89 days past due
Greater than 90 days past due on nonaccrual
Total past due
Current	3,233	3,171
Total loans	3,233	3,171
Obligations of states and political subdivisions of U.S [Member] | Other [Member]
Financing Receivable, Recorded Investment [Line Items]
30-89 days past due
Greater than 90 days past due on nonaccrual
Total past due
Current	564	739
Total loans	564	739
Other [Member] | Other [Member]
Financing Receivable, Recorded Investment [Line Items]
30-89 days past due		1
Greater than 90 days past due on nonaccrual	1	2
Total past due	1	3
Current	5,896	5,518
Total loans	$ 5,897	$ 5,521