Loans and Leases (Loans and Leases, Net of Deferred Costs and Fees) (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011
Loans and Leases Receivable, Net of Deferred Income, by Type [Line Items]
Total loans and leases	$ 12,675,607	$ 10,447,930	$ 9,702,669
Nonaccrual loans and leases	118,448	156,478
Loans and leases contractually past due 90 days and still accruing	8,451	10,077
Troubled debt restructurings	56,823	72,852
Deferred origination costs and fees	16,941	13,857
All overdrawn deposit accounts, reclassified as loans and evaluated for collectability	2,596	3,390
Commercial, Financial, And Agricultural [Member]
Loans and Leases Receivable, Net of Deferred Income, by Type [Line Items]
Total loans and leases	2,168,708	1,871,027
Real Estate - Construction [Member]
Loans and Leases Receivable, Net of Deferred Income, by Type [Line Items]
Total loans and leases	904,285	829,221
Real Estate Secured - Residential [Member]
Loans and Leases Receivable, Net of Deferred Income, by Type [Line Items]
Total loans and leases	4,047,761	3,212,562
Real Estate Secured - Commercial [Member]
Loans and Leases Receivable, Net of Deferred Income, by Type [Line Items]
Total loans and leases	3,947,447	3,136,887
Consumer [Member]
Loans and Leases Receivable, Net of Deferred Income, by Type [Line Items]
Total loans and leases	829,760	722,329
Leases [Member]
Loans and Leases Receivable, Net of Deferred Income, by Type [Line Items]
Total loans and leases	777,646	675,904
Legacy Loans And Leases [Member]
Loans and Leases Receivable, Net of Deferred Income, by Type [Line Items]
Total loans and leases	10,399,602	9,833,296
Purchased Loans And Leases [Member]
Loans and Leases Receivable, Net of Deferred Income, by Type [Line Items]
Total loans and leases	$ 2,276,005	$ 614,634