Loans, Impaired Loans (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Impaired loans [Abstract]
Unpaid Contractual Principal Balance	$ 15,652	$ 20,865
Recorded Investment with no Allowance	7,003	11,820
Recorded Investment with Allowance	6,378	6,406
Total Recorded Investment	13,381	18,226
Related Allowance	1,072	1,648
Interest income on impaired loans recognized using a cash-basis method of accounting [Abstract]
Average Recorded Investment	15,295	20,656	22,518
Interest Income Recognized	389	901	651
Commercial [Member]
Impaired loans [Abstract]
Unpaid Contractual Principal Balance	3,628	4,694
Recorded Investment with no Allowance	2,769	2,919
Recorded Investment with Allowance	519	569
Total Recorded Investment	3,288	3,488
Related Allowance	95	101
Interest income on impaired loans recognized using a cash-basis method of accounting [Abstract]
Average Recorded Investment	3,639	3,366	2,507
Interest Income Recognized	44	107	158
Commercial Real Estate [Member]
Impaired loans [Abstract]
Unpaid Contractual Principal Balance	3,629	4,856
Recorded Investment with no Allowance	1,872	3,071
Recorded Investment with Allowance	1,170	1,198
Total Recorded Investment	3,042	4,269
Related Allowance	26	22
Interest income on impaired loans recognized using a cash-basis method of accounting [Abstract]
Average Recorded Investment	4,438	7,750	8,518
Interest Income Recognized	113	505	212
Agriculture [Member]
Impaired loans [Abstract]
Unpaid Contractual Principal Balance	0	3,847
Recorded Investment with no Allowance	0	3,598
Recorded Investment with Allowance	0	0
Total Recorded Investment	0	3,598
Related Allowance	0	0
Interest income on impaired loans recognized using a cash-basis method of accounting [Abstract]
Average Recorded Investment	737	1,963	2,834
Interest Income Recognized	35	27	19
Residential Mortgage [Member]
Impaired loans [Abstract]
Unpaid Contractual Principal Balance	5,831	5,336
Recorded Investment with no Allowance	1,860	1,875
Recorded Investment with Allowance	2,963	3,194
Total Recorded Investment	4,823	5,069
Related Allowance	417	731
Interest income on impaired loans recognized using a cash-basis method of accounting [Abstract]
Average Recorded Investment	4,312	5,593	5,752
Interest Income Recognized	107	186	213
Residential Construction [Member]
Impaired loans [Abstract]
Unpaid Contractual Principal Balance	1,148	1,147
Recorded Investment with no Allowance	0	48
Recorded Investment with Allowance	1,097	1,099
Total Recorded Investment	1,097	1,147
Related Allowance	433	668
Interest income on impaired loans recognized using a cash-basis method of accounting [Abstract]
Average Recorded Investment	1,166	1,492	2,599
Interest Income Recognized	52	67	47
Consumer [Member]
Impaired loans [Abstract]
Unpaid Contractual Principal Balance	1,416	985
Recorded Investment with no Allowance	502	309
Recorded Investment with Allowance	629	346
Total Recorded Investment	1,131	655
Related Allowance	101	126
Interest income on impaired loans recognized using a cash-basis method of accounting [Abstract]
Average Recorded Investment	1,003	492	308
Interest Income Recognized	$ 38	$ 9	$ 2