Loans and Allowance for Credit Losses - Loan Portfolio Aging (Details) - USD ($)	Mar. 31, 2016	Dec. 31, 2015
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	$ 2,015,000	$ 302,000
Current	606,276,000	597,392,000
Loans	608,291,000	597,694,000
Recorded Investment Greater Than 90 Days Accruing	0	0
Non-accrual	3,679,000	2,413,000
Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	1,046,000	0
Current	97,950,000	102,197,000
Loans	98,996,000	102,197,000
Recorded Investment Greater Than 90 Days Accruing	0	0
Non-accrual	1,114,000	29,000
Agricultural land and production
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	48,000	0
Current	23,688,000	30,472,000
Loans	23,736,000	30,472,000
Recorded Investment Greater Than 90 Days Accruing	0	0
Non-accrual	0	0
Owner occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	457,000	0
Current	168,214,000	168,910,000
Loans	168,671,000	168,910,000
Recorded Investment Greater Than 90 Days Accruing	0	0
Non-accrual	506,000	347,000
Real estate construction and other land loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	0
Current	42,165,000	38,685,000
Loans	42,165,000	38,685,000
Recorded Investment Greater Than 90 Days Accruing	0	0
Non-accrual	0	0
Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	98,000
Current	118,611,000	117,146,000
Loans	118,611,000	117,244,000
Recorded Investment Greater Than 90 Days Accruing	0	0
Non-accrual	558,000	567,000
Agricultural real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	0
Current	87,354,000	74,867,000
Loans	87,354,000	74,867,000
Recorded Investment Greater Than 90 Days Accruing	0	0
Non-accrual	0	0
Other real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	0
Current	10,593,000	10,520,000
Loans	10,593,000	10,520,000
Recorded Investment Greater Than 90 Days Accruing	0	0
Non-accrual	0	0
Equity loans and lines of credit
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	447,000	166,000
Current	41,656,000	42,130,000
Loans	42,103,000	42,296,000
Recorded Investment Greater Than 90 Days Accruing	0	0
Non-accrual	1,490,000	1,457,000
Consumer and installment
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	17,000	38,000
Current	16,045,000	12,465,000
Loans	16,062,000	12,503,000
Recorded Investment Greater Than 90 Days Accruing	0	0
Non-accrual	11,000	13,000
30-59 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	1,529,000	136,000
30-59 Days Past Due | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	897,000	0
30-59 Days Past Due | Agricultural land and production
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	48,000	0
30-59 Days Past Due | Owner occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	287,000	0
30-59 Days Past Due | Real estate construction and other land loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	0
30-59 Days Past Due | Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	98,000
30-59 Days Past Due | Agricultural real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	0
30-59 Days Past Due | Other real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	0
30-59 Days Past Due | Equity loans and lines of credit
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	280,000	0
30-59 Days Past Due | Consumer and installment
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	17,000	38,000
60-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	149,000	166,000
60-89 Days Past Due | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	149,000	0
60-89 Days Past Due | Agricultural land and production
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	0
60-89 Days Past Due | Owner occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	0
60-89 Days Past Due | Real estate construction and other land loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	0
60-89 Days Past Due | Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	0
60-89 Days Past Due | Agricultural real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	0
60-89 Days Past Due | Other real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	0
60-89 Days Past Due | Equity loans and lines of credit
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	166,000
60-89 Days Past Due | Consumer and installment
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	0
Greater Than 90 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	337,000	0
Greater Than 90 Days Past Due | Commercial and industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	0
Greater Than 90 Days Past Due | Agricultural land and production
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	0
Greater Than 90 Days Past Due | Owner occupied
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	170,000	0
Greater Than 90 Days Past Due | Real estate construction and other land loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	0
Greater Than 90 Days Past Due | Commercial real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	0
Greater Than 90 Days Past Due | Agricultural real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	0
Greater Than 90 Days Past Due | Other real estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	0	0
Greater Than 90 Days Past Due | Equity loans and lines of credit
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	167,000	0
Greater Than 90 Days Past Due | Consumer and installment
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due	$ 0	$ 0