Loans and Allowance for Loan Losses, Part II (Details)	3 Months Ended
	Mar. 31, 2016 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2015 USD ($)
Loans Receivable Aging Analysis [Abstract]
30-59 Days Past Due	$ 6,392,000		$ 1,683,000
60-89 Days Past Due	851,000		1,401,000
90 Days or More Past Due	660,000		394,000
Total Past Due	7,903,000		3,478,000
Current	1,269,002,000		1,278,411,000
Total Loans Receivable	1,276,905,000		1,281,889,000
Total Loans 90 Days & Accruing	$ 0		0
Number of days past due when interest is not accrued	ninety days
Period of satisfactory performance before returning to accrual status	not less than six months
Loans with a specific allowance [Abstract]
Recorded Balance	$ 1,630,000		1,174,000
Unpaid Principal Balance	1,630,000		1,174,000
Specific Allowance	298,000		134,000
Loans without a specific allowance [Abstract]
Recorded Balance	2,715,000		2,835,000
Unpaid Principal Balance	3,658,000		4,016,000
Total Loans [Abstract]
Recorded Balance	4,345,000		4,009,000
Unpaid Principal Balance	5,288,000		5,190,000
Average recorded investment and interest income recognized [Abstract]
Average investment in impaired loans	4,419,000	$ 4,699,000
Interest income recognized	6,000	5,000
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans	3,876,000		3,412,000
Interest Lost on Nonaccrual Loans	68,000	$ 97,000
Troubled Debt Restructuring [Abstract]
Troubled Debt Restructurings Balance	1,689,000		1,743,000
Financing Receivable Modifications Performing Recorded Investment	$ 469,000		601,000
Recorded Balance of Troubled Debt Restructurings [Abstract]
Financing Receivables, Modifications during Period, Number	1	4
Financing Receivables, Modifications during Period, Balance	$ 19,000	$ 66,000
Subsequent Default, Number of Days Past Due	90 days
Real Estate Acquired Through Foreclosure	$ 347,000		477,000
Mortgage Loans Secured By Real Estate In Foreclosure	0	55,000
Pass
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	1,237,559,000		1,240,217,000
Watch
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	18,345,000		19,373,000
Substandard
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	21,001,000		22,299,000
Doubtful
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	0		0
Construction and land development
Loans Receivable Aging Analysis [Abstract]
30-59 Days Past Due	235,000		0
60-89 Days Past Due	0		0
90 Days or More Past Due	0		0
Total Past Due	235,000		0
Current	29,217,000		39,209,000
Total Loans Receivable	29,452,000		39,209,000
Total Loans 90 Days & Accruing	0		0
Loans with a specific allowance [Abstract]
Recorded Balance	0		0
Unpaid Principal Balance	0		0
Specific Allowance	0		0
Loans without a specific allowance [Abstract]
Recorded Balance	136,000		142,000
Unpaid Principal Balance	701,000		707,000
Total Loans [Abstract]
Recorded Balance	136,000		142,000
Unpaid Principal Balance	701,000		707,000
Average recorded investment and interest income recognized [Abstract]
Average investment in impaired loans	136,000	419,000
Interest income recognized	0	0
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans	136,000		142,000
Troubled Debt Restructuring [Abstract]
Troubled Debt Restructurings Balance	136,000		142,000
Construction and land development | Pass
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	29,316,000		39,067,000
Construction and land development | Watch
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	0		0
Construction and land development | Substandard
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	136,000		142,000
Construction and land development | Doubtful
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	0		0
Agricultural real estate
Loans Receivable Aging Analysis [Abstract]
30-59 Days Past Due	419,000		106,000
60-89 Days Past Due	106,000		0
90 Days or More Past Due	0		0
Total Past Due	525,000		106,000
Current	118,889,000		122,368,000
Total Loans Receivable	119,414,000		122,474,000
Total Loans 90 Days & Accruing	0		0
Loans with a specific allowance [Abstract]
Recorded Balance	430,000		430,000
Unpaid Principal Balance	430,000		430,000
Specific Allowance	0		0
Loans without a specific allowance [Abstract]
Recorded Balance	22,000		24,000
Unpaid Principal Balance	26,000		28,000
Total Loans [Abstract]
Recorded Balance	452,000		454,000
Unpaid Principal Balance	456,000		458,000
Average recorded investment and interest income recognized [Abstract]
Average investment in impaired loans	453,000	96,000
Interest income recognized	0	1,000
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans	452,000		454,000
Troubled Debt Restructuring [Abstract]
Troubled Debt Restructurings Balance	232,000		232,000
Financing Receivable Modifications Performing Recorded Investment	$ 0		0
Recorded Balance of Troubled Debt Restructurings [Abstract]
Financing Receivables, Modifications during Period, Number	0
Financing Receivables, Modifications during Period, Balance	$ 0
Agricultural real estate | Pass
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	115,439,000		118,103,000
Agricultural real estate | Watch
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	1,807,000		2,282,000
Agricultural real estate | Substandard
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	2,168,000		2,089,000
Agricultural real estate | Doubtful
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	0		0
1-4 Family residential properties
Loans Receivable Aging Analysis [Abstract]
30-59 Days Past Due	322,000		1,059,000
60-89 Days Past Due	506,000		742,000
90 Days or More Past Due	290,000		154,000
Total Past Due	1,118,000		1,955,000
Current	225,049,000		229,616,000
Total Loans Receivable	226,167,000		231,571,000
Total Loans 90 Days & Accruing	0		0
Loans with a specific allowance [Abstract]
Recorded Balance	0		0
Unpaid Principal Balance	0		0
Specific Allowance	0		0
Loans without a specific allowance [Abstract]
Recorded Balance	1,323,000		1,373,000
Unpaid Principal Balance	1,517,000		1,688,000
Total Loans [Abstract]
Recorded Balance	1,323,000		1,373,000
Unpaid Principal Balance	1,517,000		1,688,000
Average recorded investment and interest income recognized [Abstract]
Average investment in impaired loans	1,330,000	1,292,000
Interest income recognized	5,000	2,000
Loans Receivable, Modifications, Still Accruing Interest	395,000	$ 344,000
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans	928,000		975,000
Troubled Debt Restructuring [Abstract]
Troubled Debt Restructurings Balance	511,000		515,000
Financing Receivable Modifications Performing Recorded Investment	$ 395,000		397,000
Recorded Balance of Troubled Debt Restructurings [Abstract]
Financing Receivables, Modifications during Period, Number	0	1
Financing Receivables, Modifications during Period, Balance	$ 0	$ 11,000
1-4 Family residential properties | Pass
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	219,754,000		224,552,000
1-4 Family residential properties | Watch
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	1,435,000		1,454,000
1-4 Family residential properties | Substandard
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	4,978,000		5,565,000
1-4 Family residential properties | Doubtful
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	0		0
Multifamily residential properties
Loans Receivable Aging Analysis [Abstract]
30-59 Days Past Due	0		0
60-89 Days Past Due	0		0
90 Days or More Past Due	0		0
Total Past Due	0		0
Current	47,336,000		45,740,000
Total Loans Receivable	47,336,000		45,740,000
Total Loans 90 Days & Accruing	0		0
Loans with a specific allowance [Abstract]
Recorded Balance	310,000		316,000
Unpaid Principal Balance	310,000		316,000
Specific Allowance	0		0
Loans without a specific allowance [Abstract]
Recorded Balance	0		1,000
Unpaid Principal Balance	0		1,000
Total Loans [Abstract]
Recorded Balance	310,000		317,000
Unpaid Principal Balance	310,000		317,000
Average recorded investment and interest income recognized [Abstract]
Average investment in impaired loans	312,000	0
Interest income recognized	0	0
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans	310,000		317,000
Multifamily residential properties | Pass
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	46,785,000		45,180,000
Multifamily residential properties | Watch
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	241,000		243,000
Multifamily residential properties | Substandard
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	310,000		317,000
Multifamily residential properties | Doubtful
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	0		0
Commercial real estate
Loans Receivable Aging Analysis [Abstract]
30-59 Days Past Due	4,649,000		251,000
60-89 Days Past Due	187,000		67,000
90 Days or More Past Due	117,000		31,000
Total Past Due	4,953,000		349,000
Current	433,337,000		408,823,000
Total Loans Receivable	438,290,000		409,172,000
Total Loans 90 Days & Accruing	0		0
Loans with a specific allowance [Abstract]
Recorded Balance	476,000		0
Unpaid Principal Balance	476,000		0
Specific Allowance	177,000		0
Loans without a specific allowance [Abstract]
Recorded Balance	295,000		304,000
Unpaid Principal Balance	316,000		325,000
Total Loans [Abstract]
Recorded Balance	771,000		304,000
Unpaid Principal Balance	792,000		325,000
Average recorded investment and interest income recognized [Abstract]
Average investment in impaired loans	773,000	2,084,000
Interest income recognized	1,000	1,000
Loans Receivable, Modifications, Still Accruing Interest	35,000	37,000
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans	736,000		269,000
Troubled Debt Restructuring [Abstract]
Troubled Debt Restructurings Balance	121,000		124,000
Financing Receivable Modifications Performing Recorded Investment	35,000		36,000
Commercial real estate | Pass
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	416,673,000		386,769,000
Commercial real estate | Watch
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	10,440,000		10,498,000
Commercial real estate | Substandard
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	11,177,000		11,905,000
Commercial real estate | Doubtful
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	0		0
Agricultural loans
Loans Receivable Aging Analysis [Abstract]
30-59 Days Past Due	0		65,000
60-89 Days Past Due	0		74,000
90 Days or More Past Due	55,000		0
Total Past Due	55,000		139,000
Current	67,088,000		75,747,000
Total Loans Receivable	67,143,000		75,886,000
Total Loans 90 Days & Accruing	0		0
Loans with a specific allowance [Abstract]
Recorded Balance	0		0
Unpaid Principal Balance	0		0
Specific Allowance	0		0
Loans without a specific allowance [Abstract]
Recorded Balance	70,000		79,000
Unpaid Principal Balance	70,000		79,000
Total Loans [Abstract]
Recorded Balance	70,000		79,000
Unpaid Principal Balance	70,000		79,000
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans	70,000		79,000
Agricultural loans | Pass
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	66,757,000		75,437,000
Agricultural loans | Watch
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	280,000		210,000
Agricultural loans | Substandard
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	106,000		239,000
Agricultural loans | Doubtful
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	0		0
Commercial and industrial loans
Loans Receivable Aging Analysis [Abstract]
30-59 Days Past Due	661,000		65,000
60-89 Days Past Due	52,000		476,000
90 Days or More Past Due	189,000		196,000
Total Past Due	902,000		737,000
Current	296,983,000		304,323,000
Total Loans Receivable	297,885,000		305,060,000
Total Loans 90 Days & Accruing	0		0
Loans with a specific allowance [Abstract]
Recorded Balance	392,000		405,000
Unpaid Principal Balance	392,000		405,000
Specific Allowance	121,000		134,000
Loans without a specific allowance [Abstract]
Recorded Balance	639,000		670,000
Unpaid Principal Balance	795,000		932,000
Total Loans [Abstract]
Recorded Balance	1,031,000		1,075,000
Unpaid Principal Balance	1,187,000		1,337,000
Average recorded investment and interest income recognized [Abstract]
Average investment in impaired loans	1,061,000	514,000
Interest income recognized	0	$ 0
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans	1,003,000		928,000
Troubled Debt Restructuring [Abstract]
Troubled Debt Restructurings Balance	468,000		491,000
Financing Receivable Modifications Performing Recorded Investment	$ 28,000		147,000
Recorded Balance of Troubled Debt Restructurings [Abstract]
Financing Receivables, Modifications during Period, Number	1	0
Financing Receivables, Modifications during Period, Balance	$ 19,000	$ 0
Commercial and industrial loans | Pass
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	291,926,000		298,633,000
Commercial and industrial loans | Watch
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	4,142,000		4,686,000
Commercial and industrial loans | Substandard
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	1,817,000		1,741,000
Commercial and industrial loans | Doubtful
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	0		0
Consumer loans
Loans Receivable Aging Analysis [Abstract]
30-59 Days Past Due	106,000		137,000
60-89 Days Past Due	0		42,000
90 Days or More Past Due	9,000		13,000
Total Past Due	115,000		192,000
Current	39,513,000		41,387,000
Total Loans Receivable	39,628,000		41,579,000
Total Loans 90 Days & Accruing	0		0
Loans with a specific allowance [Abstract]
Recorded Balance	22,000		23,000
Unpaid Principal Balance	22,000		23,000
Specific Allowance	0		0
Loans without a specific allowance [Abstract]
Recorded Balance	230,000		242,000
Unpaid Principal Balance	233,000		256,000
Total Loans [Abstract]
Recorded Balance	252,000		265,000
Unpaid Principal Balance	255,000		279,000
Average recorded investment and interest income recognized [Abstract]
Average investment in impaired loans	264,000	294,000
Interest income recognized	0	1,000
Loans Receivable, Modifications, Still Accruing Interest	11,000	$ 40,000
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans	241,000		248,000
Troubled Debt Restructuring [Abstract]
Troubled Debt Restructurings Balance	221,000		239,000
Financing Receivable Modifications Performing Recorded Investment	$ 11,000		21,000
Recorded Balance of Troubled Debt Restructurings [Abstract]
Financing Receivables, Modifications during Period, Number	0	2
Financing Receivables, Modifications during Period, Balance	$ 0	$ 32,000
Consumer loans | Pass
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	39,319,000		41,278,000
Consumer loans | Watch
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	0		0
Consumer loans | Substandard
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	309,000		301,000
Consumer loans | Doubtful
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	0		0
All other loans
Loans Receivable Aging Analysis [Abstract]
30-59 Days Past Due	0		0
60-89 Days Past Due	0		0
90 Days or More Past Due	0		0
Total Past Due	0		0
Current	11,590,000		11,198,000
Total Loans Receivable	11,590,000		11,198,000
Total Loans 90 Days & Accruing	0		0
Loans with a specific allowance [Abstract]
Recorded Balance	0		0
Unpaid Principal Balance	0		0
Specific Allowance	0		0
Loans without a specific allowance [Abstract]
Recorded Balance	0		0
Unpaid Principal Balance	0		0
Total Loans [Abstract]
Recorded Balance	0		0
Unpaid Principal Balance	0		0
All other loans | Pass
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	11,590,000		11,198,000
All other loans | Watch
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	0		0
All other loans | Substandard
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	0		0
All other loans | Doubtful
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	0		0
Loans secured by real estate
Loans Receivable Aging Analysis [Abstract]
30-59 Days Past Due	5,625,000		1,416,000
60-89 Days Past Due	799,000		809,000
90 Days or More Past Due	407,000		185,000
Total Past Due	6,831,000		2,410,000
Current	853,828,000		845,756,000
Total Loans Receivable	860,659,000		848,166,000
Total Loans 90 Days & Accruing	0		0
Loans with a specific allowance [Abstract]
Recorded Balance	1,216,000		746,000
Unpaid Principal Balance	1,216,000		746,000
Specific Allowance	177,000		0
Loans without a specific allowance [Abstract]
Recorded Balance	1,776,000		1,844,000
Unpaid Principal Balance	2,560,000		2,749,000
Total Loans [Abstract]
Recorded Balance	2,992,000		2,590,000
Unpaid Principal Balance	3,776,000		3,495,000
Average recorded investment and interest income recognized [Abstract]
Average investment in impaired loans	3,004,000	3,891,000
Interest income recognized	6,000	$ 4,000
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans	2,562,000		2,157,000
Troubled Debt Restructuring [Abstract]
Troubled Debt Restructurings Balance	1,000,000		1,013,000
Financing Receivable Modifications Performing Recorded Investment	$ 430,000		$ 433,000
Recorded Balance of Troubled Debt Restructurings [Abstract]
Financing Receivables, Modifications during Period, Number	0	2
Financing Receivables, Modifications during Period, Balance	$ 0	$ 34,000