Nonaccrual Loans (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual loans	$ 143,877	$ 96,592
Commercial, financial and agricultural
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual loans	7,644	2,372
Commercial real estate | Commercial construction, land and land development
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual loans	102,176	59,382
Commercial real estate | Other commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual loans	17,230	15,275
Consumer Portfolio Segment
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual loans	659	651
Residential real estate | Residential Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual loans	484	497
Residential real estate | Residential Mortgage
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-accrual loans	$ 15,684	$ 18,415