Loans - Summary of Troubled Debt Restructurings by Loan Class, Excluding Purchased Non-Covered and Covered Loans, Classified Separately under Restructured Terms (Detail) (Excluding Purchased Non-Covered and 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	74	67	52
Troubled debt restructuring loans	$ 17,362	$ 15,596	$ 18,513
Loans Currently Paying Under Restructured Terms [Member] | Commercial, Financial and Agricultural [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	4	4	5
Troubled debt restructuring loans	268	515	799
Loans Currently Paying Under Restructured Terms [Member] | Real Estate - Construction and Development [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	10	8	5
Troubled debt restructuring loans	1,916	1,896	1,883
Loans Currently Paying Under Restructured Terms [Member] | Real Estate - Commercial and Farmland [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	19	16	16
Troubled debt restructuring loans	8,733	6,396	8,878
Loans Currently Paying Under Restructured Terms [Member] | Real Estate - Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	30	32	26
Troubled debt restructuring loans	6,365	6,699	6,953
Loans Currently Paying Under Restructured Terms [Member] | Consumer Installment Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	11	7
Troubled debt restructuring loans	80	90
Loans That Have Defaulted Under Restructured Terms [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	24	25	8
Troubled debt restructuring loans	3,851	5,301	4,755
Loans That Have Defaulted Under Restructured Terms [Member] | Commercial, Financial and Agricultural [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	2	3
Troubled debt restructuring loans	482	525
Loans That Have Defaulted Under Restructured Terms [Member] | Real Estate - Construction and Development [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	2	2	1
Troubled debt restructuring loans	66	32	43
Loans That Have Defaulted Under Restructured Terms [Member] | Real Estate - Commercial and Farmland [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	5	5	3
Troubled debt restructuring loans	1,316	2,789	3,595
Loans That Have Defaulted Under Restructured Terms [Member] | Real Estate - Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	13	13	3
Troubled debt restructuring loans	1,961	1,953	1,111
Loans That Have Defaulted Under Restructured Terms [Member] | Consumer Installment Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	2	2	1
Troubled debt restructuring loans	$ 26	$ 2	$ 6