Loans - Summary of Troubled Debt Restructurings by Loan Class of Covered Loans, Classified Separately Under Terms (Detail) (Covered Loans [Member], USD $) In Thousands, unless otherwise specified	Mar. 31, 2014 Contract	Dec. 31, 2013 Contract	Mar. 31, 2013 Contract
Loans Currently Paying Under Restructured Terms [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	101	95	76
Troubled debt restructuring loans	$ 16,960	$ 20,077	$ 20,040
Loans Currently Paying Under Restructured Terms [Member] | Commercial, Financial and Agricultural [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	5	5	1
Troubled debt restructuring loans	43	45	36
Loans Currently Paying Under Restructured Terms [Member] | Real Estate - Construction and Development [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	2	5	8
Troubled debt restructuring loans	374	3,273	5,022
Loans Currently Paying Under Restructured Terms [Member] | Real Estate - Commercial and Farmland [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	18	15	14
Troubled debt restructuring loans	6,962	7,543	6,603
Loans Currently Paying Under Restructured Terms [Member] | Real Estate - Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	75	68	52
Troubled debt restructuring loans	9,576	9,206	8,373
Loans Currently Paying Under Restructured Terms [Member] | Consumer Installment Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	1	2	1
Troubled debt restructuring loans	5	10	6
Loans That Have Defaulted Under Restructured Terms [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	29	29	19
Troubled debt restructuring loans	10,840	7,187	7,516
Loans That Have Defaulted Under Restructured Terms [Member] | Commercial, Financial and Agricultural [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	1	1	1
Troubled debt restructuring loans	40	40
Loans That Have Defaulted Under Restructured Terms [Member] | Real Estate - Construction and Development [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	6	2	3
Troubled debt restructuring loans	2,928	34	788
Loans That Have Defaulted Under Restructured Terms [Member] | Real Estate - Commercial and Farmland [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	3	3	5
Troubled debt restructuring loans	4,370	3,658	4,819
Loans That Have Defaulted Under Restructured Terms [Member] | Real Estate - Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	19	23	10
Troubled debt restructuring loans	$ 3,502	$ 3,455	$ 1,909