Loans and Allowance for Loan Losses (Details)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) alternative	Jun. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)	Jun. 30, 2016 USD ($)	Dec. 31, 2015 USD ($)	Jun. 30, 2015 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						$ 3,692,000	$ 3,478,000
Provision for Loan and Lease Losses	$ 733,000	$ 143,000	$ 846,000	$ 408,000
Financing Receivable, Allowance for Credit Losses, Period Increase (Decrease)	733,000	143,000	846,000	408,000	$ 1,318,000
Gross loans						1,316,515,000	1,283,709,000
Less [Abstract]
Net deferred loan fees, premiums and discounts						2,674,000	2,788,000
Allowance for loan losses	14,736,000	14,106,000	14,576,000	13,682,000	13,682,000	15,164,000	14,576,000	$ 13,931,000
Net loans						1,298,677,000	1,266,345,000
Loans held for sale						1,346,000	968,000
Impaired Loans [Abstract]
Minimum value of loans individually measured for impairment			$ 250,000
Number of alternatives for measuring impaired loans receivable | alternative			3
Allowance for Loan Losses [Abstract]
Balance, beginning of period	14,736,000	14,106,000	$ 14,576,000	13,682,000	13,682,000
Losses charged off	(739,000)	(381,000)	(976,000)	(471,000)	(906,000)
Recoveries	434,000	63,000	718,000	312,000	482,000
Balance, end of period	15,164,000	13,931,000	$ 15,164,000	13,931,000	14,576,000
Ending Balance [Abstract]
Individually evaluated for impairment						297,000	134,000	537,000
Collectively evaluated for impairment						14,867,000	14,442,000	13,394,000
Loans [Abstract]
Ending balance						1,315,187,000	1,281,889,000	1,059,103,000
Ending Balance [Abstract]
Individually evaluated for impairment						2,006,000	1,174,000	1,766,000
Collectively evaluated for impairment						1,313,181,000	1,280,715,000	1,057,337,000
Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						189,000	0
Gross loans						33,820,000	39,232,000
Agricultural real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						561,000	106,000
Gross loans						122,384,000	122,579,000
1-4 Family residential properties
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						1,150,000	1,955,000
Gross loans						219,817,000	231,383,000
Ending Balance [Abstract]
Period When Loans are Charged-down			180 days
Multifamily residential properties
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						240,000	0
Gross loans						47,243,000	45,765,000
Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						521,000	349,000
Gross loans						446,356,000	409,487,000
Loans Receivable Additional Information [Abstract]
Debt coverage ratio			1.20x
Amortization period of loans			twenty years
Commercial real estate | Minimum [Member]
Loans Receivable Additional Information [Abstract]
Maximum Loan-to-value Ratio (in hundredths)			65.00%
Commercial real estate | Maximum [Member]
Loans Receivable Additional Information [Abstract]
Maximum Loan-to-value Ratio (in hundredths)			80.00%
Loans secured by real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						2,661,000	2,410,000
Gross loans						869,620,000	848,446,000
Agricultural loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						20,000	139,000
Gross loans						72,855,000	75,998,000
Commercial and industrial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						504,000	737,000
Gross loans						301,873,000	305,851,000
Loans Receivable Additional Information [Abstract]
Maximum Loan-to-value Ratio (in hundredths)			80.00%
Amortization period of loans			seven years
Loans Receivable, Time Period			one year
Consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						60,000	192,000
Financing Receivable, Allowance for Credit Losses, Period Increase (Decrease)	88,000	258,000	$ 211,000	262,000	633,000
Gross loans						38,448,000	42,097,000
Less [Abstract]
Allowance for loan losses	710,000	386,000	642,000	386,000	386,000	733,000	642,000	382,000
Allowance for Loan Losses [Abstract]
Balance, beginning of period	710,000	386,000	642,000	386,000	386,000
Losses charged off	(109,000)	(304,000)	(222,000)	(360,000)	(553,000)
Recoveries	44,000	42,000	102,000	94,000	176,000
Balance, end of period	733,000	382,000	733,000	382,000	642,000
Ending Balance [Abstract]
Individually evaluated for impairment						0	0	0
Collectively evaluated for impairment						733,000	642,000	382,000
Loans [Abstract]
Ending balance						41,677,000	43,739,000	15,451,000
Ending Balance [Abstract]
Individually evaluated for impairment						21,000	0	0
Collectively evaluated for impairment						41,656,000	43,739,000	15,451,000
All other loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						447,000	0
Gross loans						33,719,000	11,317,000
Agricultural and Farm Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans						195,200,000	198,600,000
Less [Abstract]
Decrease in loans receivable			$ (3,400,000)
Loans Receivable Additional Information [Abstract]
Maximum Loan-to-value Ratio (in hundredths)			65.00%
Amortization period of loans			twenty five years
Loans Receivable, Time Period			one year
Other Grain Farming [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans						162,700,000	161,500,000
Less [Abstract]
Decrease in loans receivable			$ 1,200,000
Motels and Hotels Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans						65,000,000
Non-residential Buildings [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans						116,400,000
Residential Buildings [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross loans						64,400,000
Unsecured Open-end Loans [Member]
Ending Balance [Abstract]
Period When Loans are Charged-down			180 days
Other Secured Loans [Member]
Ending Balance [Abstract]
Period When Loans are Charged-down			120 days
Commercial/ Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Allowance for Credit Losses, Period Increase (Decrease)	388,000	(123,000)	$ 613,000	235,000	451,000
Less [Abstract]
Allowance for loan losses	11,789,000	11,459,000	11,379,000	10,914,000	10,914,000	11,995,000	11,379,000	11,294,000
Allowance for Loan Losses [Abstract]
Balance, beginning of period	11,789,000	11,459,000	11,379,000	10,914,000	10,914,000
Losses charged off	(572,000)	(62,000)	(612,000)	(71,000)	(289,000)
Recoveries	390,000	20,000	615,000	216,000	303,000
Balance, end of period	11,995,000	11,294,000	11,995,000	11,294,000	11,379,000
Ending Balance [Abstract]
Individually evaluated for impairment						297,000	134,000	537,000
Collectively evaluated for impairment						11,698,000	11,245,000	10,757,000
Loans [Abstract]
Ending balance						857,150,000	807,736,000	696,596,000
Ending Balance [Abstract]
Individually evaluated for impairment						1,555,000	744,000	1,766,000
Collectively evaluated for impairment						855,595,000	806,992,000	694,830,000
Agricultural/ Agricultural Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Allowance for Credit Losses, Period Increase (Decrease)	179,000	20,000	111,000	(49,000)	(25,000)
Less [Abstract]
Allowance for loan losses	1,270,000	1,291,000	1,337,000	1,360,000	1,360,000	1,449,000	1,337,000	1,312,000
Allowance for Loan Losses [Abstract]
Balance, beginning of period	1,270,000	1,291,000	1,337,000	1,360,000	1,360,000
Losses charged off	0	0	0	0	0
Recoveries	0	1,000	1,000	1,000	2,000
Balance, end of period	1,449,000	1,312,000	1,449,000	1,312,000	1,337,000
Ending Balance [Abstract]
Individually evaluated for impairment						0	0	0
Collectively evaluated for impairment						1,449,000	1,337,000	1,312,000
Loans [Abstract]
Ending balance						194,814,000	198,066,000	171,376,000
Ending Balance [Abstract]
Individually evaluated for impairment						430,000	430,000	0
Collectively evaluated for impairment						194,384,000	197,636,000	171,376,000
Residential Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Allowance for Credit Losses, Period Increase (Decrease)	56,000	(7,000)	72,000	(20,000)	267,000
Less [Abstract]
Allowance for loan losses	926,000	753,000	$ 994,000	790,000	790,000	924,000	994,000	731,000
Loans Receivable Additional Information [Abstract]
Maximum Loan-to-value Ratio (in hundredths)			80.00%
Amortization period of loans			twenty five years
Balloon period			five years
Allowance for Loan Losses [Abstract]
Balance, beginning of period	926,000	753,000	$ 994,000	790,000	790,000
Losses charged off	(58,000)	(15,000)	(142,000)	(40,000)	(64,000)
Recoveries	0	0	0	1,000	1,000
Balance, end of period	924,000	731,000	924,000	731,000	994,000
Ending Balance [Abstract]
Individually evaluated for impairment						0	0	0
Collectively evaluated for impairment						924,000	994,000	731,000
Loans [Abstract]
Ending balance						221,546,000	232,348,000	175,680,000
Ending Balance [Abstract]
Individually evaluated for impairment						0	0	0
Collectively evaluated for impairment						221,546,000	232,348,000	175,680,000
Unallocated
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Allowance for Credit Losses, Period Increase (Decrease)	22,000	(5,000)	(161,000)	(20,000)	(8,000)
Less [Abstract]
Allowance for loan losses	41,000	217,000	224,000	232,000	232,000	63,000	224,000	212,000
Allowance for Loan Losses [Abstract]
Balance, beginning of period	41,000	217,000	224,000	232,000	232,000
Losses charged off	0	0	0	0	0
Recoveries	0	0	0	0	0
Balance, end of period	$ 63,000	$ 212,000	$ 63,000	$ 212,000	$ 224,000
Ending Balance [Abstract]
Individually evaluated for impairment						0	0	0
Collectively evaluated for impairment						63,000	224,000	212,000
Loans [Abstract]
Ending balance						0	0	0
Ending Balance [Abstract]
Individually evaluated for impairment						0	0	0
Collectively evaluated for impairment						0	0	$ 0
Financing Receivables, 30 to 59 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						1,411,000	1,683,000
Financing Receivables, 30 to 59 Days Past Due [Member] | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						0	0
Financing Receivables, 30 to 59 Days Past Due [Member] | Agricultural real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						131,000	106,000
Financing Receivables, 30 to 59 Days Past Due [Member] | 1-4 Family residential properties
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						371,000	1,059,000
Financing Receivables, 30 to 59 Days Past Due [Member] | Multifamily residential properties
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						240,000	0
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						52,000	251,000
Financing Receivables, 30 to 59 Days Past Due [Member] | Loans secured by real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						794,000	1,416,000
Financing Receivables, 30 to 59 Days Past Due [Member] | Agricultural loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						20,000	65,000
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial and industrial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						108,000	65,000
Financing Receivables, 30 to 59 Days Past Due [Member] | Consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						52,000	137,000
Financing Receivables, 30 to 59 Days Past Due [Member] | All other loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						437,000	0
Financing Receivables, 60 to 89 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						1,294,000	1,401,000
Financing Receivables, 60 to 89 Days Past Due [Member] | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						189,000	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Agricultural real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						430,000	0
Financing Receivables, 60 to 89 Days Past Due [Member] | 1-4 Family residential properties
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						554,000	742,000
Financing Receivables, 60 to 89 Days Past Due [Member] | Multifamily residential properties
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						0	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						0	67,000
Financing Receivables, 60 to 89 Days Past Due [Member] | Loans secured by real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						1,173,000	809,000
Financing Receivables, 60 to 89 Days Past Due [Member] | Agricultural loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						0	74,000
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial and industrial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						114,000	476,000
Financing Receivables, 60 to 89 Days Past Due [Member] | Consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						7,000	42,000
Financing Receivables, 60 to 89 Days Past Due [Member] | All other loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						0	0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						987,000	394,000
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Construction and land development
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						0	0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Agricultural real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						0	0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | 1-4 Family residential properties
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						225,000	154,000
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Multifamily residential properties
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						0	0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						469,000	31,000
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Loans secured by real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						694,000	185,000
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Agricultural loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						0	0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial and industrial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						282,000	196,000
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						1,000	13,000
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | All other loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable, Recorded Investment, Past Due						$ 10,000	$ 0