Outstanding Commitments and Contingent Liabilities (Details) (USD $) In Thousands, unless otherwise specified			3 Months Ended
	Mar. 31, 2013 item	Dec. 31, 2012	Mar. 31, 2013 Maximum	Mar. 31, 2013 Commitments to extend credit	Dec. 31, 2012 Commitments to extend credit	Mar. 31, 2013 Standby letters of credit	Dec. 31, 2012 Standby letters of credit
Credit Commitments and Contingencies
Financial instruments whose contract amounts represent credit risk:				$ 495,670	$ 483,373	$ 12,327	$ 12,305
Term for guarantee			1 year
Liabilities for potential obligations under guarantees	$ 0	$ 0
Number of futures, forwards, swaps or option contracts, or other financial instruments	0