Summary of Loans, Net of Unearned Income (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment, net of unearned income	$ 1,588,694	$ 1,559,039
Covered under loss share agreements	143,170	151,682
Total Loans held for investment, net of unearned income	1,731,864	1,710,721
Loans held for sale	1,743	883
Loans held for investment, net of unearned income, percentage	91.73%	91.13%
Covered loan percentage	8.27%	8.87%
Loans and leases receivable net reported amount covered and not covered percentage	100.00%	100.00%
Commercial Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment, net of unearned income	872,491	847,315
Loans held for investment, net of unearned income, percentage	50.38%	49.53%
Commercial Loans | Construction Development And Other Land
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment, net of unearned income	45,661	35,255
Covered under loss share agreements	15,956	15,865
Loans held for investment, net of unearned income, percentage	2.64%	2.06%
Commercial Loans | Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment, net of unearned income	94,403	95,455
Covered under loss share agreements	3,062	3,325
Loans held for investment, net of unearned income, percentage	5.45%	5.58%
Commercial Loans | Multi-family Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment, net of unearned income	75,594	70,197
Covered under loss share agreements	1,903	1,933
Loans held for investment, net of unearned income, percentage	4.36%	4.10%
Commercial Loans | Single-family Non-owner Occupied
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment, net of unearned income	137,969	135,559
Covered under loss share agreements	6,794	7,449
Loans held for investment, net of unearned income, percentage	7.97%	7.92%
Commercial Loans | Non-farm Non-residential Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment, net of unearned income	484,361	475,911
Covered under loss share agreements	31,458	34,646
Loans held for investment, net of unearned income, percentage	27.97%	27.82%
Commercial Loans | Agricultural
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment, net of unearned income	2,093	2,324
Covered under loss share agreements	162	164
Loans held for investment, net of unearned income, percentage	0.12%	0.14%
Commercial Loans | Farmland Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment, net of unearned income	32,410	32,614
Covered under loss share agreements	817	873
Loans held for investment, net of unearned income, percentage	1.87%	1.91%
Consumer Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment, net of unearned income	640,124	636,485
Loans held for investment, net of unearned income, percentage	36.96%	37.20%
Consumer Real Estate | Home Equity Lines
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment, net of unearned income	113,137	111,770
Covered under loss share agreements	66,895	69,206
Loans held for investment, net of unearned income, percentage	6.53%	6.53%
Consumer Real Estate | Single Family Owner Occupied
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment, net of unearned income	492,627	496,012
Covered under loss share agreements	15,287	16,919
Loans held for investment, net of unearned income, percentage	28.45%	28.99%
Consumer Real Estate | Owner occupied construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment, net of unearned income	34,360	28,703
Covered under loss share agreements	727	1,184
Loans held for investment, net of unearned income, percentage	1.98%	1.68%
Consumer and Other Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment, net of unearned income	76,079	75,239
Loans held for investment, net of unearned income, percentage	4.39%	4.40%
Consumer and Other Loans | Consumer Loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment, net of unearned income	72,111	71,313
Covered under loss share agreements	109	118
Loans held for investment, net of unearned income, percentage	4.16%	4.17%
Consumer and Other Loans | Other Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment, net of unearned income	$ 3,968	$ 3,926
Loans held for investment, net of unearned income, percentage	0.23%	0.23%