Income Taxes Income Tax Reconciliation (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Tax Disclosure [Abstract]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate	35.00%
Expected income taxes	$ 7,852	$ 6,265	$ 4,649
Tax-exempt income	(761)	(618)	(511)
Nondeductible interest expense	14	16	20
State taxes, net of federal taxes	1,264	914	417
Other items	41	52	47
Effect of marginal tax rate	0	(100)	(100)
Total	$ 8,410	$ 6,529	$ 4,522
Effective State Statutory Income Tax Rate	9.50%	7.30%