Loans, Impaired Financing Receivable (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Impaired Financing Receivable [Abstract]
Unpaid Principal Balance	$ 12,708		$ 12,066
Recorded Investment With No Allowance	7,733		7,218
Recorded Investment With Allowance	3,293		3,200
Total Recorded Investment	11,026		10,418
Related Allowance	566		582
Average Recorded Investment	10,862	8,800
Interest income recognized on impaired loans	67	19
Interest income recognized on a cash basis on impaired loans	14	19
Mortgages [Member]
Impaired Financing Receivable [Abstract]
Average Recorded Investment	284	0
Interest income recognized on impaired loans	2	0
Interest income recognized on a cash basis on impaired loans	0	0
Home Equity [Member]
Impaired Financing Receivable [Abstract]
Average Recorded Investment	137	93
Interest income recognized on impaired loans	1	1
Interest income recognized on a cash basis on impaired loans	0	1
Commercial [Member]
Impaired Financing Receivable [Abstract]
Average Recorded Investment	8,785	8,228
Interest income recognized on impaired loans	45	18
Interest income recognized on a cash basis on impaired loans	14	18
Agricultural [Member]
Impaired Financing Receivable [Abstract]
Average Recorded Investment	0	0
Interest income recognized on impaired loans	0	0
Interest income recognized on a cash basis on impaired loans	0	0
Construction [Member]
Impaired Financing Receivable [Abstract]
Average Recorded Investment	0	0
Interest income recognized on impaired loans	0	0
Interest income recognized on a cash basis on impaired loans	0	0
Real Estate Loans [Member] | Mortgages [Member]
Impaired Financing Receivable [Abstract]
Unpaid Principal Balance	378		309
Recorded Investment With No Allowance	146		150
Recorded Investment With Allowance	208		136
Total Recorded Investment	354		286
Related Allowance	24		8
Real Estate Loans [Member] | Home Equity [Member]
Impaired Financing Receivable [Abstract]
Unpaid Principal Balance	137		138
Recorded Investment With No Allowance	0		0
Recorded Investment With Allowance	137		138
Total Recorded Investment	137		138
Related Allowance	14		14
Real Estate Loans [Member] | Commercial [Member]
Impaired Financing Receivable [Abstract]
Unpaid Principal Balance	10,157		10,669
Recorded Investment With No Allowance	5,911		6,476
Recorded Investment With Allowance	2,639		2,617
Total Recorded Investment	8,550		9,093
Related Allowance	528		559
Real Estate Loans [Member] | Agricultural [Member]
Impaired Financing Receivable [Abstract]
Unpaid Principal Balance	0		0
Recorded Investment With No Allowance	0		0
Recorded Investment With Allowance	0		0
Total Recorded Investment	0		0
Related Allowance	0		0
Real Estate Loans [Member] | Construction [Member]
Impaired Financing Receivable [Abstract]
Unpaid Principal Balance	0		0
Recorded Investment With No Allowance	0		0
Recorded Investment With Allowance	0		0
Total Recorded Investment	0		0
Related Allowance	0		0
Consumer [Member]
Impaired Financing Receivable [Abstract]
Unpaid Principal Balance	0		0
Recorded Investment With No Allowance	0		0
Recorded Investment With Allowance	0		0
Total Recorded Investment	0		0
Related Allowance	0		0
Average Recorded Investment	0	0
Interest income recognized on impaired loans	0	0
Interest income recognized on a cash basis on impaired loans	0	0
Other Commercial Loans [Member]
Impaired Financing Receivable [Abstract]
Unpaid Principal Balance	2,036		950
Recorded Investment With No Allowance	1,676		592
Recorded Investment With Allowance	309		309
Total Recorded Investment	1,985		901
Related Allowance	0		1
Average Recorded Investment	1,656	479
Interest income recognized on impaired loans	19	0
Interest income recognized on a cash basis on impaired loans	0	0
Other Agricultural Loans [Member]
Impaired Financing Receivable [Abstract]
Unpaid Principal Balance	0		0
Recorded Investment With No Allowance	0		0
Recorded Investment With Allowance	0		0
Total Recorded Investment	0		0
Related Allowance	0		0
Average Recorded Investment	0	0
Interest income recognized on impaired loans	0	0
Interest income recognized on a cash basis on impaired loans	0	0
State and Political Subdivision Loans [Member]
Impaired Financing Receivable [Abstract]
Unpaid Principal Balance	0		0
Recorded Investment With No Allowance	0		0
Recorded Investment With Allowance	0		0
Total Recorded Investment	0		0
Related Allowance	0		0
Average Recorded Investment	0	0
Interest income recognized on impaired loans	0	0
Interest income recognized on a cash basis on impaired loans	$ 0	$ 0