Loans (Details 8) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013 Loans	Dec. 31, 2012 Loans	Mar. 31, 2013 Trouble Debt Restructuring [Member] Loans	Mar. 31, 2012 Trouble Debt Restructuring [Member] Loans	Mar. 31, 2013 Commercial, industrial, and agricultural [Member] Loans	Dec. 31, 2012 Commercial, industrial, and agricultural [Member] Loans	Mar. 31, 2013 Commercial, industrial, and agricultural [Member] Trouble Debt Restructuring [Member] Loans	Mar. 31, 2012 Commercial, industrial, and agricultural [Member] Trouble Debt Restructuring [Member] Loans	Mar. 31, 2013 Commercial mortgages [Member] Loans	Dec. 31, 2012 Commercial mortgages [Member] Loans	Mar. 31, 2013 Commercial mortgages [Member] Trouble Debt Restructuring [Member] Loans	Mar. 31, 2012 Commercial mortgages [Member] Trouble Debt Restructuring [Member] Loans	Mar. 31, 2013 Residential real estate [Member] Loans	Dec. 31, 2012 Residential real estate [Member] Loans	Mar. 31, 2013 Residential real estate [Member] Trouble Debt Restructuring [Member] Loans	Mar. 31, 2012 Residential real estate [Member] Trouble Debt Restructuring [Member] Loans	Mar. 31, 2013 Consumer [Member] Loans	Dec. 31, 2012 Consumer [Member] Loans	Mar. 31, 2013 Consumer [Member] Trouble Debt Restructuring [Member] Loans	Mar. 31, 2012 Consumer [Member] Trouble Debt Restructuring [Member] Loans	Mar. 31, 2013 Credit cards [Member] Loans	Dec. 31, 2012 Credit cards [Member] Loans	Mar. 31, 2013 Credit cards [Member] Trouble Debt Restructuring [Member] Loans	Mar. 31, 2012 Credit cards [Member] Trouble Debt Restructuring [Member] Loans
Loans by Class Modified as Troubled Debt Restructurings
Number of Loans	11	10	1	4	2	2	0	0	9	8	1	4	0	0	0	0	0	0	0	0	0	0	0	0
Pre-Modification, Outstanding Recorded Investment			$ 346	$ 2,556			$ 0	$ 0			$ 346	$ 2,556			$ 0	$ 0			$ 0	$ 0			$ 0	$ 0
Post-Modification, Outstanding Recorded Investment			$ 403	$ 2,556			$ 0	$ 0			$ 403	$ 2,556			$ 0	$ 0			$ 0	$ 0			$ 0	$ 0