Loans - Analysis of Information Pertaining to Impaired Loans, Excluding Purchased Non-Covered and Covered Loans (Detail) (Excluding Purchased Non-Covered and Covered Loans [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Contractual Principal Balance	$ 58,035	$ 77,144	$ 61,024
Recorded Investment With No Allowance
Recorded Investment With Allowance	45,577	55,989	46,417
Total impaired loans	45,577	55,989	46,417
Related Allowance	4,324	4,839	3,871
Average Recorded Investment	45,997	56,808	51,721
Commercial, Financial and Agricultural [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Contractual Principal Balance	5,421	7,818	6,240
Recorded Investment With No Allowance
Recorded Investment With Allowance	3,719	4,555	4,618
Total impaired loans	3,719	4,555	4,618
Related Allowance	394	740	435
Average Recorded Investment	4,169	4,747	4,844
Real Estate - Construction and Development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Contractual Principal Balance	10,636	20,633	11,363
Recorded Investment With No Allowance
Recorded Investment With Allowance	6,033	11,273	5,867
Total impaired loans	6,033	11,273	5,867
Related Allowance	736	922	512
Average Recorded Investment	5,950	11,144	8,341
Real Estate - Commercial and Farmland [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Contractual Principal Balance	19,983	22,996	18,456
Recorded Investment With No Allowance
Recorded Investment With Allowance	17,282	18,676	15,479
Total impaired loans	17,282	18,676	15,479
Related Allowance	1,972	1,816	1,443
Average Recorded Investment	16,380	19,793	17,559
Real Estate - Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Contractual Principal Balance	21,307	24,777	24,342
Recorded Investment With No Allowance
Recorded Investment With Allowance	17,996	20,792	19,970
Total impaired loans	17,996	20,792	19,970
Related Allowance	1,211	1,344	1,472
Average Recorded Investment	18,983	20,320	20,335
Consumer Installment Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Contractual Principal Balance	688	920	623
Recorded Investment With No Allowance
Recorded Investment With Allowance	547	693	483
Total impaired loans	547	693	483
Related Allowance	11	17	9
Average Recorded Investment	$ 515	$ 804	$ 642