Loans and Allowance for Loan Losses (Details 1) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011
Summary of nonperforming and restructured assets
Past due over 90 days and still accruing	$ 731	$ 798	$ 1,413
Nonaccrual	22,101	21,187	24,088
Other acquired loans covered by escrow			4,951
Restructured	17,784	1,041	1,059
Total nonperforming and restructured loans	40,616	23,026	31,511
Other real estate owned and repossessed assets	9,796	16,640	16,723
Total nonperforming and restructured assets	$ 50,412	$ 39,666	$ 48,234
Nonperforming and restructured loans to total loans	1.30%	0.76%	1.06%
Nonperforming and restructured assets to total assets	0.86%	0.71%	0.88%