Allowance for Credit Losses, Aging Analysis of Loan Portfolio by the Time Past Due (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 89 Days Past Due	$ 1,451,000	$ 547,000
90 Days and Still Accruing	0	0
Nonaccrual	2,596,000	9,298,000
Total Past Due	4,047,000	9,845,000
Current	1,384,189,000	1,237,057,000
Total Loans & Leases	1,388,236,000	1,246,902,000
Interest income forgone on nonaccrual loans	30,500	209,000	385,000
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 89 Days Past Due	773,000	150,000
90 Days and Still Accruing	0	0
Nonaccrual	0	0
Total Past Due	773,000	150,000
Current	406,741,000	350,398,000
Total Loans & Leases	407,514,000	350,548,000
Agricultural Real Estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 89 Days Past Due	607,000	0
90 Days and Still Accruing	0	0
Nonaccrual	0	5,423,000
Total Past Due	607,000	5,423,000
Current	327,657,000	306,569,000
Total Loans & Leases	328,264,000	311,992,000
Real Estate Construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 89 Days Past Due	0	0
90 Days and Still Accruing	0	0
Nonaccrual	0	0
Total Past Due	0	0
Current	41,092,000	32,680,000
Total Loans & Leases	41,092,000	32,680,000
Residential 1st Mortgages [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 89 Days Past Due	0	23,000
90 Days and Still Accruing	0	0
Nonaccrual	324,000	445,000
Total Past Due	324,000	468,000
Current	150,968,000	139,789,000
Total Loans & Leases	151,292,000	140,257,000
Home Equity [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 89 Days Past Due	52,000	70,000
90 Days and Still Accruing	0	0
Nonaccrual	406,000	213,000
Total Past Due	458,000	283,000
Current	35,019,000	41,759,000
Total Loans & Leases	35,477,000	42,042,000
Agricultural [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 89 Days Past Due	0	0
90 Days and Still Accruing	0	0
Nonaccrual	35,000	3,198,000
Total Past Due	35,000	3,198,000
Current	256,379,000	217,834,000
Total Loans & Leases	256,414,000	221,032,000
Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 89 Days Past Due	0	293,000
90 Days and Still Accruing	0	0
Nonaccrual	1,815,000	0
Total Past Due	1,815,000	293,000
Current	148,583,000	143,000,000
Total Loans & Leases	150,398,000	143,293,000
Consumer & Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 89 Days Past Due	19,000	11,000
90 Days and Still Accruing	0	0
Nonaccrual	16,000	19,000
Total Past Due	35,000	30,000
Current	5,017,000	5,028,000
Total Loans & Leases	5,052,000	5,058,000
Leases [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 - 89 Days Past Due	0
90 Days and Still Accruing	0
Nonaccrual	0
Total Past Due	0
Current	12,733,000
Total Loans & Leases	$ 12,733,000	$ 0