Loans and Allowance for Loan Losses - Summary of Purchased Non-Covered Loans According to Loan Type (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total non-covered loans	$ 22,744	$ 22,377	$ 23,382
Purchased Non-Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total non-covered loans	437,269	448,753
Purchased Non-Covered Loans [Member] | Commercial, Financial and Agricultural [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total non-covered loans	30,810	32,141
Purchased Non-Covered Loans [Member] | Real Estate - Construction and Development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total non-covered loans	31,820	31,176
Purchased Non-Covered Loans [Member] | Real Estate - Commercial and Farmland [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total non-covered loans	174,281	179,898
Purchased Non-Covered Loans [Member] | Real Estate - Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total non-covered loans	196,078	200,851
Purchased Non-Covered Loans [Member] | Consumer Installment Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total non-covered loans	$ 4,280	$ 4,687