Loans - Summary of Covered Loans According to Loan Type (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	$ 443,517	$ 507,712	$ 601,737
Commercial, Financial and Agricultural [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	27,371	32,606	41,372
Real Estate - Construction and Development [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	52,972	70,184	83,991
Real Estate - Commercial and Farmland [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	255,102	278,506	322,393
Real Estate - Residential [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	107,107	125,056	150,683
Consumer Installment Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Covered loans	$ 965	$ 1,360	$ 3,298