Loans & Leases (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Gross Loans & Leases	$ 2,183,265	$ 2,001,487
Less: Unearned Income	5,664	5,128
Total Loans & Leases	2,177,601	1,996,359
Less: Allowance for Credit Losses	47,919	41,523	$ 35,401
Loans & Leases, Net	2,129,682	1,954,836
Collateral on borrowing lines	664,700
Federal Home Loan Bank [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Collateral on borrowing lines	664,700
Maximum borrowing capacity	566,500
Federal Reserve Bank [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Collateral on borrowing lines	548,000
Maximum borrowing capacity	356,100
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Gross Loans & Leases	674,445	609,602
Total Loans & Leases	668,046	603,650
Less: Allowance for Credit Losses	11,110	10,063	7,842
Agricultural Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Gross Loans & Leases	467,685	424,034
Total Loans & Leases	467,685	424,034
Less: Allowance for Credit Losses	9,450	6,881	4,185
Real Estate Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Gross Loans & Leases	176,462	151,974
Total Loans & Leases	176,462	151,974
Less: Allowance for Credit Losses	3,223	2,485	1,669
Residential 1st Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Gross Loans & Leases	242,247	206,405
Total Loans & Leases	242,247	206,405
Less: Allowance for Credit Losses	865	789	1,022
Home Equity Lines and Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Gross Loans & Leases	31,625	33,056
Total Loans & Leases	31,625	33,056
Less: Allowance for Credit Losses	2,140	2,146	2,426
Agricultural [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Gross Loans & Leases	295,325	293,966
Total Loans & Leases	295,325	293,966
Less: Allowance for Credit Losses	7,381	6,308	6,104
Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Gross Loans & Leases	217,577	210,804
Total Loans & Leases	217,577	210,804
Less: Allowance for Credit Losses	8,515	7,836	8,195
Consumer & Other [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Gross Loans & Leases	6,913	6,592
Total Loans & Leases	6,913	6,592
Less: Allowance for Credit Losses	200	175	218
Unallocated [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans & Leases	0	0
Less: Allowance for Credit Losses	1,449	1,546	1,529
Leases [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Gross Loans & Leases	70,986	65,054
Total Loans & Leases	71,721	65,878
Less: Allowance for Credit Losses	$ 3,586	$ 3,294	$ 2,211