Loans - Summary of Trouble Debt Restructuring by Loan Class of Covered Loans (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013
Financing Receivable, Modifications [Line Items]
Troubled debt restructuring loans	$ 21,200	$ 20,900	$ 23,300
Covered Loans [Member] | Accruing Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	103	100	75
Troubled debt restructuring loans	22,775	22,243	19,762
Covered Loans [Member] | Accruing Loans [Member] | Commercial, Financial and Agricultural [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	1	1	1
Troubled debt restructuring loans	14	13	36
Covered Loans [Member] | Accruing Loans [Member] | Real Estate - Construction and Development [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	3	3	8
Troubled debt restructuring loans	3,254	3,256	5,022
Covered Loans [Member] | Accruing Loans [Member] | Real Estate - Commercial and Farmland [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	14	13	13
Troubled debt restructuring loans	7,461	7,255	6,438
Covered Loans [Member] | Accruing Loans [Member] | Real Estate - Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	85	83	53
Troubled debt restructuring loans	12,046	11,719	8,266
Covered Loans [Member] | Non-Accruing Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	27	24	20
Troubled debt restructuring loans	5,025	5,021	7,794
Covered Loans [Member] | Non-Accruing Loans [Member] | Commercial, Financial and Agricultural [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	5	5	1
Troubled debt restructuring loans	68	71
Covered Loans [Member] | Non-Accruing Loans [Member] | Real Estate - Construction and Development [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	5	4	3
Troubled debt restructuring loans	49	52	788
Covered Loans [Member] | Non-Accruing Loans [Member] | Real Estate - Commercial and Farmland [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	7	5	6
Troubled debt restructuring loans	3,872	3,946	4,984
Covered Loans [Member] | Non-Accruing Loans [Member] | Real Estate - Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	9	8	9
Troubled debt restructuring loans	1,031	942	2,016
Covered Loans [Member] | Non-Accruing Loans [Member] | Consumer Installment Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	1	2	1
Troubled debt restructuring loans	$ 5	$ 10	$ 6