Loans - Summary of Delinquencies by Class (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Financing Receivable, Recorded Investment [Line Items]
Total gross loans, 30-89 days past due	$ 4,386	$ 4,901
Total gross loans, Greater than 90 days past due on nonaccrual	17,766	47,216
Total gross loans, past due	22,152	52,117
Total gross loans, Current	711,788	721,441
Loans, gross	733,940	773,558
30-89 days past due	4,386	4,901
Greater than 90 days past due on nonaccrual	19,879	53,028
Total past due	24,265	57,929
Current	716,763	729,807
Total loans	741,028	787,736
Total commercial real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
30-89 days past due	1,394	668
Greater than 90 days past due on nonaccrual	12,643	41,955
Total past due	14,037	42,623
Current	444,285	450,131
Total loans	458,322	492,754
Total single family residential loans [Member]
Financing Receivable, Recorded Investment [Line Items]
30-89 days past due	2,335	3,157
Greater than 90 days past due on nonaccrual	6,061	9,271
Total past due	8,396	12,428
Current	161,897	173,076
Total loans	170,293	185,504
Total consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
30-89 days past due	426	760
Greater than 90 days past due on nonaccrual	273	489
Total past due	699	1,249
Current	50,672	51,522
Total loans	51,371	52,771
Total Other [Member]
Financing Receivable, Recorded Investment [Line Items]
30-89 days past due	2	2
Total past due	2	2
Current	9,119	7,324
Total loans	9,121	7,326
Other Loans Held for Sale [Member]
Financing Receivable, Recorded Investment [Line Items]
Greater than 90 days past due on nonaccrual	(2,113)	(5,812)
Total past due	(2,113)	(5,812)
Current	(4,975)	(8,366)
Total loans	(7,088)	(14,178)
Commercial Real Estate Other Receivable [Member]
Financing Receivable, Recorded Investment [Line Items]
30-89 days past due	390
Greater than 90 days past due on nonaccrual	8,217
Total past due	8,607
Current	64,046
Total loans	72,653
Commercial Real Estate Other Receivable [Member] | Total commercial real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
30-89 days past due		94
Greater than 90 days past due on nonaccrual		27,085
Total past due		27,179
Current		64,975
Total loans		92,154
Multifamily residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	12,547	17,945
30-89 days past due	245
Total past due	245
Current	12,302
Total loans	12,547
Multifamily residential [Member] | Total commercial real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Current		17,945
Total loans		17,945
Nonfarm nonresidential [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	368,297	373,018
30-89 days past due	759
Greater than 90 days past due on nonaccrual	4,426
Total past due	5,185
Current	367,937
Total loans	373,122
Nonfarm nonresidential [Member] | Total commercial real estate [Member]
Financing Receivable, Recorded Investment [Line Items]
30-89 days past due		574
Greater than 90 days past due on nonaccrual		14,870
Total past due		15,444
Current		367,211
Total loans		382,655
Single family residential revolving open end loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	59,715	58,971
30-89 days past due	214
Greater than 90 days past due on nonaccrual	912
Total past due	1,126
Current	58,589
Total loans	59,715
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		379
Greater than 90 days past due on nonaccrual		843
Total past due		1,222
Current		57,749
Total loans		58,971
Single family residential closed end, first lien [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	105,069	119,580
30-89 days past due	1,913
Greater than 90 days past due on nonaccrual	4,872
Total past due	6,785
Current	98,284
Total loans	105,069
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		2,633
Greater than 90 days past due on nonaccrual		7,957
Total past due		10,590
Current		108,990
Total loans		119,580
Single family residential closed end junior lien [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	5,509	6,953
30-89 days past due	208
Greater than 90 days past due on nonaccrual	277
Total past due	485
Current	5,024
Total loans	5,509
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		145
Greater than 90 days past due on nonaccrual		471
Total past due		616
Current		6,337
Total loans		6,953
Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	51,921
30-89 days past due	229
Greater than 90 days past due on nonaccrual	902
Total past due	1,131
Current	50,790
Total loans	51,921
Commercial and Industrial [Member] | Total consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
30-89 days past due		314
Greater than 90 days past due on nonaccrual		1,313
Total past due		1,627
Current		47,754
Total loans		49,381
Credit cards [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	19	195
Greater than 90 days past due on nonaccrual	19
Total past due	19
Total loans	19
Credit cards [Member] | Total consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Greater than 90 days past due on nonaccrual		16
Total past due		16
Current		179
Total loans		195
Consumer - others [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	51,352	52,576
30-89 days past due	426
Greater than 90 days past due on nonaccrual	254
Total past due	680
Current	50,672
Total loans	51,352
Consumer - others [Member] | Total consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
30-89 days past due		760
Greater than 90 days past due on nonaccrual		473
Total past due		1,233
Current		51,343
Total loans		52,576
Farmland [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	3,166	3,513
Total loans	3,166	3,513
Obligations of states and political subdivisions of U.S [Member]
Financing Receivable, Recorded Investment [Line Items]
Current	667	903
Total loans	667	903
Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans, gross	9,121
30-89 days past due	2	2
Total past due	2	2
Current	5,286	2,908
Total loans	$ 5,288	$ 2,910