Loans - Summary of Trouble Debt Restructuring by Loan Class of Covered Loans (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014 Contract	Dec. 31, 2013 Contract	Jun. 30, 2013 Contract	Jun. 30, 2012 Contract
Financing Receivable, Modifications [Line Items]
Troubled debt restructuring loans	$ 21,100	$ 20,900	$ 20,600
Covered Loans [Member]
Financing Receivable, Modifications [Line Items]
Troubled debt restructuring loans	9,221	8,409	10,253
Covered Loans [Member] | Accruing Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	87	76	70	70
Troubled debt restructuring loans	9,221	8,409	10,253	10,253
Covered Loans [Member] | Accruing Loans [Member] | Commercial, Financial and Agricultural [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts			1
Troubled debt restructuring loans			40
Covered Loans [Member] | Accruing Loans [Member] | Real Estate - Construction and Development [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts			2
Troubled debt restructuring loans			2,159
Covered Loans [Member] | Accruing Loans [Member] | Real Estate - Commercial and Farmland [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	5	4	4
Troubled debt restructuring loans	1,066	579	573
Covered Loans [Member] | Accruing Loans [Member] | Real Estate - Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	82	72	63
Troubled debt restructuring loans	8,155	7,830	7,481
Covered Loans [Member] | Non-Accruing Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	12	11	4	4
Troubled debt restructuring loans	597	686	151	151
Covered Loans [Member] | Non-Accruing Loans [Member] | Commercial, Financial and Agricultural [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	1	2
Troubled debt restructuring loans	24	67
Covered Loans [Member] | Non-Accruing Loans [Member] | Real Estate - Construction and Development [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	1	1	1
Troubled debt restructuring loans	14	16	10
Covered Loans [Member] | Non-Accruing Loans [Member] | Real Estate - Commercial and Farmland [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	2	1	1
Troubled debt restructuring loans	152	134	19
Covered Loans [Member] | Non-Accruing Loans [Member] | Real Estate - Residential [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	7	6	2
Troubled debt restructuring loans	403	464	122
Covered Loans [Member] | Non-Accruing Loans [Member] | Consumer Installment Loans [Member]
Financing Receivable, Modifications [Line Items]
Number of contracts	1	1
Troubled debt restructuring loans	$ 4	$ 5