Loans and Allowance for Loan Losses - Schedule of Carrying Amount of Impaired Loans (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Financing Receivable, Impaired [Line Items]
Carrying Amount	$ 286,690	$ 315,433
Construction, Land Development and Other Land Loans [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount	10,223	11,348
Secured by 1-4 Family Residential Properties [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount	55,764	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	119,574	122,430
Commercial and Industrial Loans [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount	17,385	37,772
Impaired Loans with No Related Allowance Recorded [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount	8,056	18,124
Unpaid Principal Balance	8,056	18,124
Related Allowances	0
Impaired Loans with No Related Allowance Recorded [Member] \| Construction, Land Development and Other Land Loans [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount	1,707	4,590
Unpaid Principal Balance	1,707	4,590
Related Allowances	0
Impaired Loans with No Related Allowance Recorded [Member] \| Secured by 1-4 Family Residential Properties [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount	97	103
Unpaid Principal Balance	97	103
Related Allowances	0
Impaired Loans with No Related Allowance Recorded [Member] \| Secured by Multi-family Residential Properties [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount	0	1,053
Unpaid Principal Balance	0	1,053
Related Allowances	0
Impaired Loans with No Related Allowance Recorded [Member] \| Secured by Non-farm, Non-residential Properties [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount	6,252	11,844
Unpaid Principal Balance	6,252	11,844
Related Allowances	0
Impaired Loans with No Related Allowance Recorded [Member] \| Commercial and Industrial Loans [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount	0	534
Unpaid Principal Balance	0	534
Related Allowances	0
Impaired Loans with an Allowance Recorded [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount	3,101	14,661
Unpaid Principal Balance	3,101	14,661
Related Allowances	1,118	3,302
Impaired Loans with an Allowance Recorded [Member] \| Construction, Land Development and Other Land Loans [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount	789	1,407
Unpaid Principal Balance	789	1,407
Related Allowances	100	232
Impaired Loans with an Allowance Recorded [Member] \| Secured by 1-4 Family Residential Properties [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount	0	185
Unpaid Principal Balance	0	185
Related Allowances	0	11
Impaired Loans with an Allowance Recorded [Member] \| Secured by Multi-family Residential Properties [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount	2,312	6,474
Unpaid Principal Balance	2,312	6,474
Related Allowances	1,018	2,005
Impaired Loans with an Allowance Recorded [Member] \| Secured by Non-farm, Non-residential Properties [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount	0	6,376
Unpaid Principal Balance	0	6,376
Related Allowances	0	835
Impaired Loans with an Allowance Recorded [Member] \| Commercial and Industrial Loans [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount	0	219
Unpaid Principal Balance	0	219
Related Allowances	0	219
Impaired Loans [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount	11,157	32,785
Unpaid Principal Balance	11,157	32,785
Related Allowances	1,118	3,302
Impaired Loans [Member] \| Construction, Land Development and Other Land Loans [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount	2,496	5,997
Unpaid Principal Balance	2,496	5,997
Related Allowances	100	232
Impaired Loans [Member] \| Secured by 1-4 Family Residential Properties [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount	97	288
Unpaid Principal Balance	97	288
Related Allowances	0	11
Impaired Loans [Member] \| Secured by Multi-family Residential Properties [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount	2,312	7,527
Unpaid Principal Balance	2,312	7,527
Related Allowances	1,018	2,005
Impaired Loans [Member] \| Secured by Non-farm, Non-residential Properties [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount	6,252	18,220
Unpaid Principal Balance	6,252	18,220
Related Allowances	0	835
Impaired Loans [Member] \| Commercial and Industrial Loans [Member]
Financing Receivable, Impaired [Line Items]
Carrying Amount	0	753
Unpaid Principal Balance	0	753
Related Allowances	$ 0	$ 219