Condensed Parent Company Information (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Assets
Cash on deposit with bank subsidiary	$ 241,507	$ 216,167	$ 212,002	$ 350,872
Premises and equipment	74,371	69,975
Other assets	53,543	40,970
Total assets	3,244,910	3,290,474
Liabilities and shareholders' equity
Trust preferred securities	46,394	133,925
Other liabilities	19,740	37,385
Total liabilities	2,888,793	2,945,324
Total shareholders' equity	356,117	345,150
Total liabilities and shareholders' equity	3,244,910	3,290,474
Parent Company
Assets
Cash on deposit with bank subsidiary	3,335	3,324	21,826	4,322
Investment in wholly-owned subsidiaries, at equity	399,688	388,528
Premises and equipment	152	161
Other assets	1,637	1,633
Total assets	404,812	393,646
Liabilities and shareholders' equity
Trust preferred securities	46,394	46,394
Other liabilities	2,301	2,102
Total liabilities	48,695	48,496
Total shareholders' equity	356,117	345,150
Total liabilities and shareholders' equity	$ 404,812	$ 393,646