Loans (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Summary of net loans, by loan type
Total loans	$ 4,935,482	$ 5,053,475
Commercial, financial and agricultural
Summary of net loans, by loan type
Total loans	2,496,601	2,560,102
Real estate - mortgage
Summary of net loans, by loan type
Total loans	864,187	895,870
Real estate construction
Summary of net loans, by loan type
Total loans	1,269,146	1,273,389
Consumer
Summary of net loans, by loan type
Total loans	87,660	94,109
Foreign
Summary of net loans, by loan type
Total loans	$ 217,888	$ 230,005