Fair Value of Financial Instruments (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Investment Securities Available-for-Sale: [Abstract]
Total Assets Measured at Fair Value On a Recurring Basis	$ 417,991	$ 479,820
Carrying Amount [Member]
Assets: [Abstract]
Cash and Cash Equivalents	129,426	101,660
Investment Securities Available-for-Sale: [Abstract]
Government Agency & Government-Sponsored Entities	26,823
Obligations of States and Political Subdivisions	5,665
Mortgage Backed Securities	352,772
Corporate Securities	22,558
Other	10,173
Total Assets Measured at Fair Value On a Recurring Basis	417,991	479,820
Investment Securities Held-to-Maturity: [Abstract]
Obligations of States and Political Subdivisions	65,694
Mortgage Backed Securities	484
Other	2,214
Total Investment Securities Held-to-Maturity	68,392	63,092
FHLB Stock	7,368	7,035
Loans, Net of Deferred Loan Fees & Allowance: [Abstract]
Commercial Real Estate	344,084
Agricultural Real Estate	309,115
Real Estate Construction	31,694
Residential 1st Mortgages	139,038
Home Equity Lines and Loans	38,807
Agricultural	210,595
Commercial	135,330
Consumer & Other	4,876
Unallocated Allowance	(854)
Total Loans, Net of Deferred Loan Fees & Allowance	1,212,685	1,130,061
Accrued Interest Receivable	6,389	6,368
Deposits:
Demand	462,251	389,639
Interest Bearing Transaction	259,141	1,236,558
Savings and Money Market	541,526
Time	459,108
Total Deposits	1,722,026
FHLB Advances & Securities Sold Under Agreement to Repurchase		60,530
Subordinated Debentures	10,310	10,310
Accrued Interest Payable	498	911
Estimated Fair Value [Member]
Assets: [Abstract]
Cash and Cash Equivalents	129,426	101,660
Investment Securities Available-for-Sale: [Abstract]
Government Agency & Government-Sponsored Entities	26,823
Obligations of States and Political Subdivisions	5,665
Mortgage Backed Securities	352,772
Corporate Securities	22,558
Other	10,173
Total Assets Measured at Fair Value On a Recurring Basis	417,991	479,820
Investment Securities Held-to-Maturity: [Abstract]
Obligations of States and Political Subdivisions	67,987
Mortgage Backed Securities	496
Other	2,214
Total Investment Securities Held-to-Maturity	70,697	65,874
Loans, Net of Deferred Loan Fees & Allowance: [Abstract]
Commercial Real Estate	349,524
Agricultural Real Estate	316,302
Real Estate Construction	32,024
Residential 1st Mortgages	144,203
Home Equity Lines and Loans	41,419
Agricultural	209,578
Commercial	134,647
Consumer & Other	4,847
Unallocated Allowance	(854)
Total Loans, Net of Deferred Loan Fees & Allowance	1,231,690	1,162,261
Accrued Interest Receivable	6,389	6,368
Deposits:
Demand	462,251	389,639
Interest Bearing Transaction	259,141	1,237,849
Savings and Money Market	541,526
Time	459,993
Total Deposits	1,722,911
FHLB Advances & Securities Sold Under Agreement to Repurchase		63,000
Subordinated Debentures	5,750	5,953
Accrued Interest Payable	498	911
Estimated Fair Value [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets: [Abstract]
Cash and Cash Equivalents	129,426
Investment Securities Available-for-Sale: [Abstract]
Government Agency & Government-Sponsored Entities	21,731
Obligations of States and Political Subdivisions	0
Mortgage Backed Securities	0
Corporate Securities	4,020
Other	9,863
Total Assets Measured at Fair Value On a Recurring Basis	35,614
Investment Securities Held-to-Maturity: [Abstract]
Obligations of States and Political Subdivisions	0
Mortgage Backed Securities	0
Other	0
Total Investment Securities Held-to-Maturity	0
Loans, Net of Deferred Loan Fees & Allowance: [Abstract]
Commercial Real Estate	0
Agricultural Real Estate	0
Real Estate Construction	0
Residential 1st Mortgages	0
Home Equity Lines and Loans	0
Agricultural	0
Commercial	0
Consumer & Other	0
Unallocated Allowance	0
Total Loans, Net of Deferred Loan Fees & Allowance	0
Accrued Interest Receivable	0
Deposits:
Demand	462,251
Interest Bearing Transaction	259,141
Savings and Money Market	541,526
Time	0
Total Deposits	1,262,918
Subordinated Debentures	0
Estimated Fair Value [Member] \| Other Observable Inputs (Level 2) [Member]
Assets: [Abstract]
Cash and Cash Equivalents	0
Investment Securities Available-for-Sale: [Abstract]
Government Agency & Government-Sponsored Entities	5,092
Obligations of States and Political Subdivisions	0
Mortgage Backed Securities	352,772
Corporate Securities	18,538
Other	310
Total Assets Measured at Fair Value On a Recurring Basis	376,712
Investment Securities Held-to-Maturity: [Abstract]
Obligations of States and Political Subdivisions	60,177
Mortgage Backed Securities	496
Other	2,214
Total Investment Securities Held-to-Maturity	62,887
Loans, Net of Deferred Loan Fees & Allowance: [Abstract]
Commercial Real Estate	0
Agricultural Real Estate	0
Real Estate Construction	0
Residential 1st Mortgages	0
Home Equity Lines and Loans	0
Agricultural	0
Commercial	0
Consumer & Other	0
Unallocated Allowance	0
Total Loans, Net of Deferred Loan Fees & Allowance	0
Accrued Interest Receivable	0
Deposits:
Demand	0
Interest Bearing Transaction	0
Savings and Money Market	0
Time	459,993
Total Deposits	459,993
Subordinated Debentures	5,750
Accrued Interest Payable	498
Estimated Fair Value [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Assets: [Abstract]
Cash and Cash Equivalents	0
Investment Securities Available-for-Sale: [Abstract]
Government Agency & Government-Sponsored Entities	0
Obligations of States and Political Subdivisions	5,665
Mortgage Backed Securities	0
Corporate Securities	0
Other	0
Total Assets Measured at Fair Value On a Recurring Basis	5,665
Investment Securities Held-to-Maturity: [Abstract]
Obligations of States and Political Subdivisions	7,810
Mortgage Backed Securities	0
Other	0
Total Investment Securities Held-to-Maturity	7,810
Loans, Net of Deferred Loan Fees & Allowance: [Abstract]
Commercial Real Estate	349,524
Agricultural Real Estate	316,302
Real Estate Construction	32,024
Residential 1st Mortgages	144,203
Home Equity Lines and Loans	41,419
Agricultural	209,578
Commercial	134,647
Consumer & Other	4,847
Unallocated Allowance	(854)
Total Loans, Net of Deferred Loan Fees & Allowance	1,231,690
Accrued Interest Receivable	6,389
Deposits:
Demand	0
Interest Bearing Transaction	0
Savings and Money Market	0
Time	0
Total Deposits	0
Subordinated Debentures	0
Accrued Interest Payable	$ 0

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