Loans and Allowance for Credit Losses - Loan Portfolio by Risk Rating (Details) - USD ($)	Dec. 31, 2015	Dec. 31, 2014
Financing Receivable, Recorded Investment
Loans	$ 597,694,000	$ 572,442,000
Pass
Financing Receivable, Recorded Investment
Loans	537,211,000	530,021,000
Special Mention
Financing Receivable, Recorded Investment
Loans	28,719,000	8,663,000
Substandard
Financing Receivable, Recorded Investment
Loans	31,764,000	33,758,000
Doubtful
Financing Receivable, Recorded Investment
Loans	0	0
Commercial and industrial
Financing Receivable, Recorded Investment
Loans	102,197,000	89,007,000
Commercial and industrial | Pass
Financing Receivable, Recorded Investment
Loans	77,783,000	78,333,000
Commercial and industrial | Special Mention
Financing Receivable, Recorded Investment
Loans	22,607,000	2,345,000
Commercial and industrial | Substandard
Financing Receivable, Recorded Investment
Loans	1,807,000	8,329,000
Commercial and industrial | Doubtful
Financing Receivable, Recorded Investment
Loans	0	0
Agricultural land and production
Financing Receivable, Recorded Investment
Loans	30,472,000	39,140,000
Agricultural land and production | Pass
Financing Receivable, Recorded Investment
Loans	20,422,000	39,140,000
Agricultural land and production | Special Mention
Financing Receivable, Recorded Investment
Loans	0	0
Agricultural land and production | Substandard
Financing Receivable, Recorded Investment
Loans	10,050,000	0
Agricultural land and production | Doubtful
Financing Receivable, Recorded Investment
Loans	0	0
Owner occupied
Financing Receivable, Recorded Investment
Loans	168,910,000	176,804,000
Owner occupied | Pass
Financing Receivable, Recorded Investment
Loans	163,570,000	170,568,000
Owner occupied | Special Mention
Financing Receivable, Recorded Investment
Loans	3,785,000	2,778,000
Owner occupied | Substandard
Financing Receivable, Recorded Investment
Loans	1,555,000	3,458,000
Owner occupied | Doubtful
Financing Receivable, Recorded Investment
Loans	0	0
Real estate construction and other land loans
Financing Receivable, Recorded Investment
Loans	38,685,000	38,923,000
Real estate construction and other land loans | Pass
Financing Receivable, Recorded Investment
Loans	34,916,000	32,114,000
Real estate construction and other land loans | Special Mention
Financing Receivable, Recorded Investment
Loans	644,000	1,130,000
Real estate construction and other land loans | Substandard
Financing Receivable, Recorded Investment
Loans	3,125,000	5,679,000
Real estate construction and other land loans | Doubtful
Financing Receivable, Recorded Investment
Loans	0	0
Commercial real estate
Financing Receivable, Recorded Investment
Loans	117,244,000	106,788,000
Commercial real estate | Pass
Financing Receivable, Recorded Investment
Loans	110,833,000	95,831,000
Commercial real estate | Special Mention
Financing Receivable, Recorded Investment
Loans	1,683,000	215,000
Commercial real estate | Substandard
Financing Receivable, Recorded Investment
Loans	4,728,000	10,742,000
Commercial real estate | Doubtful
Financing Receivable, Recorded Investment
Loans	0	0
Agricultural real estate
Financing Receivable, Recorded Investment
Loans	74,867,000	57,501,000
Agricultural real estate | Pass
Financing Receivable, Recorded Investment
Loans	66,347,000	55,018,000
Agricultural real estate | Special Mention
Financing Receivable, Recorded Investment
Loans	0	2,123,000
Agricultural real estate | Substandard
Financing Receivable, Recorded Investment
Loans	8,520,000	360,000
Agricultural real estate | Doubtful
Financing Receivable, Recorded Investment
Loans	0	0
Other real estate
Financing Receivable, Recorded Investment
Loans	10,520,000	6,611,000
Other real estate | Pass
Financing Receivable, Recorded Investment
Loans	10,520,000	6,611,000
Other real estate | Special Mention
Financing Receivable, Recorded Investment
Loans	0	0
Other real estate | Substandard
Financing Receivable, Recorded Investment
Loans	0	0
Other real estate | Doubtful
Financing Receivable, Recorded Investment
Loans	0	0
Equity loans and lines of credit
Financing Receivable, Recorded Investment
Loans	42,296,000	47,575,000
Equity loans and lines of credit | Pass
Financing Receivable, Recorded Investment
Loans	40,332,000	42,334,000
Equity loans and lines of credit | Special Mention
Financing Receivable, Recorded Investment
Loans	0	72,000
Equity loans and lines of credit | Substandard
Financing Receivable, Recorded Investment
Loans	1,964,000	5,169,000
Equity loans and lines of credit | Doubtful
Financing Receivable, Recorded Investment
Loans	0	0
Consumer and installment
Financing Receivable, Recorded Investment
Loans	12,503,000	10,093,000
Consumer and installment | Pass
Financing Receivable, Recorded Investment
Loans	12,488,000	10,072,000
Consumer and installment | Special Mention
Financing Receivable, Recorded Investment
Loans	0	0
Consumer and installment | Substandard
Financing Receivable, Recorded Investment
Loans	15,000	21,000
Consumer and installment | Doubtful
Financing Receivable, Recorded Investment
Loans	$ 0	$ 0