Loans - Summary of Financial Receivable Nonaccrual Basis (Detail) (USD $)	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	$ 200,000
Non-Covered Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	31,811,000	38,885,000	44,421,000
Non-Covered Loan [Member] | Commercial, Financial and Agricultural [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	4,326,000	4,138,000	4,968,000
Non-Covered Loan [Member] | Real Estate - Construction and Development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	5,448,000	9,281,000	8,979,000
Non-Covered Loan [Member] | Real Estate - Commercial and Farmland [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	8,963,000	11,962,000	13,728,000
Non-Covered Loan [Member] | Real Estate - Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	12,423,000	12,595,000	15,542,000
Non-Covered Loan [Member] | Consumer Installment Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	651,000	909,000	1,204,000
Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	88,939,000	115,712,000	151,225,000
Covered Loans [Member] | Commercial, Financial and Agricultural [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	8,729,000	10,765,000	13,406,000
Covered Loans [Member] | Real Estate - Construction and Development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	17,039,000	20,027,000	28,225,000
Covered Loans [Member] | Real Estate - Commercial and Farmland [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	47,427,000	55,946,000	71,271,000
Covered Loans [Member] | Real Estate - Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	15,459,000	28,672,000	37,669,000
Covered Loans [Member] | Consumer Installment Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	$ 285,000	$ 302,000	$ 654,000