Loans and Allowance for Loan Losses - Schedule of Carrying Amount of Impaired Loans (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Financing Receivable, Impaired [Line Items]
Carrying Amount	$ 280,226	$ 315,433
Construction, Land Development and Other Land Loans [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount	9,813	11,348
Secured by 1-4 Family Residential Properties [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount	53,535	61,599
Secured by Multi-family Residential Properties [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount	20,459	22,095
Secured by Non-farm, Non-residential Properties [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount	112,512	122,430
Commercial and Industrial Loans [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount	18,216	37,772
Impaired Loans with No Related Allowance Recorded [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount	7,770	18,124
Unpaid Principal Balance	7,770	18,124
Impaired Loans with No Related Allowance Recorded [Member] \| Construction, Land Development and Other Land Loans [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount	1,445	4,590
Unpaid Principal Balance	1,445	4,590
Impaired Loans with No Related Allowance Recorded [Member] \| Secured by 1-4 Family Residential Properties [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount	96	103
Unpaid Principal Balance	96	103
Impaired Loans with No Related Allowance Recorded [Member] \| Secured by Multi-family Residential Properties [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount		1,053
Unpaid Principal Balance		1,053
Impaired Loans with No Related Allowance Recorded [Member] \| Secured by Non-farm, Non-residential Properties [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount	6,229	11,844
Unpaid Principal Balance	6,229	11,844
Impaired Loans with No Related Allowance Recorded [Member] \| Commercial and Industrial Loans [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount		534
Unpaid Principal Balance		534
Impaired Loans with an Allowance Recorded [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount	3,378	14,661
Unpaid Principal Balance	3,378	14,661
Related Allowances	1,329	3,302
Impaired Loans with an Allowance Recorded [Member] \| Construction, Land Development and Other Land Loans [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount	604	1,407
Unpaid Principal Balance	604	1,407
Related Allowances	71	232
Impaired Loans with an Allowance Recorded [Member] \| Secured by 1-4 Family Residential Properties [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount		185
Unpaid Principal Balance		185
Related Allowances		11
Impaired Loans with an Allowance Recorded [Member] \| Secured by Multi-family Residential Properties [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount	2,774	6,474
Unpaid Principal Balance	2,774	6,474
Related Allowances	1,258	2,005
Impaired Loans with an Allowance Recorded [Member] \| Secured by Non-farm, Non-residential Properties [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount		6,376
Unpaid Principal Balance		6,376
Related Allowances		835
Impaired Loans with an Allowance Recorded [Member] \| Commercial and Industrial Loans [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount		219
Unpaid Principal Balance		219
Related Allowances		219
Impaired Loans [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount	11,148	32,785
Unpaid Principal Balance	11,148	32,785
Related Allowances	1,329	3,302
Impaired Loans [Member] \| Construction, Land Development and Other Land Loans [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount	2,049	5,997
Unpaid Principal Balance	2,049	5,997
Related Allowances	71	232
Impaired Loans [Member] \| Secured by 1-4 Family Residential Properties [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount	96	288
Unpaid Principal Balance	96	288
Related Allowances		11
Impaired Loans [Member] \| Secured by Multi-family Residential Properties [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount	2,774	7,527
Unpaid Principal Balance	2,774	7,527
Related Allowances	1,258	2,005
Impaired Loans [Member] \| Secured by Non-farm, Non-residential Properties [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount	6,229	18,220
Unpaid Principal Balance	6,229	18,220
Related Allowances		835
Impaired Loans [Member] \| Commercial and Industrial Loans [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount		753
Unpaid Principal Balance		753
Related Allowances		$ 219