Loans - Summary of Troubled Debt Restructurings by Loan Class, Excluding Purchased Non-Covered and Covered Loans (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013
Financing Receivable, Modifications [Line Items]
Troubled debt restructuring loans	$ 21,100	$ 20,900	$ 20,600
Excluding Purchased Non-Covered and Covered Loans [Member]
Financing Receivable, Modifications [Line Items]
Troubled debt restructuring loans	17,337	17,214	18,015
Excluding Purchased Non-Covered and Covered Loans [Member] | Accruing Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	86	72	61
Troubled debt restructuring loans	17,337	17,214	18,015
Excluding Purchased Non-Covered and Covered Loans [Member] | Accruing Loans [Member] | Commercial, Financial and Agricultural [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	3	4	7
Troubled debt restructuring loans	257	515	1,059
Excluding Purchased Non-Covered and Covered Loans [Member] | Accruing Loans [Member] | Real Estate - Construction and Development [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	12	8	7
Troubled debt restructuring loans	2,080	1,896	1,946
Excluding Purchased Non-Covered and Covered Loans [Member] | Accruing Loans [Member] | Real Estate - Commercial and Farmland [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	19	17	16
Troubled debt restructuring loans	7,590	6,913	7,529
Excluding Purchased Non-Covered and Covered Loans [Member] | Accruing Loans [Member] | Real Estate - Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	38	37	30
Troubled debt restructuring loans	7,335	7,818	7,468
Excluding Purchased Non-Covered and Covered Loans [Member] | Accruing Loans [Member] | Consumer Installment Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	14	6	1
Troubled debt restructuring loans	75	72	13
Excluding Purchased Non-Covered and Covered Loans [Member] | Non-Accruing Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	22	20	9
Troubled debt restructuring loans	3,743	3,683	2,568
Excluding Purchased Non-Covered and Covered Loans [Member] | Non-Accruing Loans [Member] | Commercial, Financial and Agricultural [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	3	3
Troubled debt restructuring loans	465	525
Excluding Purchased Non-Covered and Covered Loans [Member] | Non-Accruing Loans [Member] | Real Estate - Construction and Development [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	2	2	1
Troubled debt restructuring loans	32	32	29
Excluding Purchased Non-Covered and Covered Loans [Member] | Non-Accruing Loans [Member] | Real Estate - Commercial and Farmland [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	4	4	2
Troubled debt restructuring loans	2,151	2,273	1,493
Excluding Purchased Non-Covered and Covered Loans [Member] | Non-Accruing Loans [Member] | Real Estate - Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	8	8	6
Troubled debt restructuring loans	1,044	834	1,046
Excluding Purchased Non-Covered and Covered Loans [Member] | Non-Accruing Loans [Member] | Consumer Installment Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	5	3
Troubled debt restructuring loans	$ 51	$ 19