Loans and Allowance for Loan Losses, Part II (Details)		3 Months Ended	12 Months Ended
		Dec. 31, 2015 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Loans Receivable Aging Analysis [Abstract]
30 to 59 Days Past Due		$ 1,683,000	$ 1,683,000	$ 1,133,000
60 to 89 Days Past Due		1,401,000	1,401,000	321,000
90 Days or More Past Due		394,000	394,000	1,433,000
Total Past Due		3,478,000	3,478,000	2,887,000
Current		1,278,411,000	1,278,411,000	1,059,519,000
Total Loans Receivable		1,281,889,000	1,281,889,000	1,062,406,000
Total Loans Greater than 90 Days Past Due and Still Accruing		0	$ 0	0
Number of days past due when interest is not accrued			ninety days
Period of satisfactory performance before returning to accrual status			six months
Loans with a specific allowance [Abstract]
Recorded Balance		1,174,000	$ 1,174,000	1,407,000
Unpaid Principal Balance		1,174,000	1,174,000	4,261,000
Specific Allowance		134,000	134,000	263,000
Loans without a specific allowance [Abstract]
Recorded Balance		2,835,000	2,835,000	3,133,000
Unpaid Principal Balance		4,016,000	4,016,000	7,902,000
Total Loans [Abstract]
Recorded Balance		4,009,000	4,009,000	4,540,000
Unpaid Principal Balance		5,190,000	5,190,000	12,163,000
Average recorded investment and interest income recognized [Abstract]
Average investment in impaired loans			4,712,000	4,946,000	$ 7,118,000
Interest income recognized			28,000	17,000	31,000
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans		3,412,000	3,412,000	4,105,000
Interest Lost on Nonaccrual Loans			48,000,000	71,000,000	45,000,000
Troubled Debt Restructuring [Abstract]
Troubled Debt Restructurings Balance		1,743,000	1,743,000	2,860,000
Troubled Debt Restructuring, Allowance		0	0	234,000
Recorded Balance of Troubled Debt Restructurings [Abstract]
Troubled Debt Restructurings Balance		1,743,000	1,743,000	2,860,000
Financing Receivable Modifications Performing Recorded Investment		601,000	601,000	435,000
Financing Receivables, Modifications during Period, Balance			$ 1,004,000	$ 795,000
Financing Receivables, Modifications during Period, Number			19	7
Subsequent Default, Number of Days Past Due			90 days
Other real estate owned		477,000	$ 477,000	$ 263,000
Mortgage Loans Secured By Real Estate In Foreclosure		55,000
Pass [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		1,240,217,000	1,240,217,000	1,026,901,000
Watch [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		19,373,000	19,373,000	25,696,000
Substandard [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		22,299,000	22,299,000	9,809,000
Doubtful [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		0	0	0
Construction and land development
Loans Receivable Aging Analysis [Abstract]
30 to 59 Days Past Due		0	0	297,000
60 to 89 Days Past Due		0	0	25,000
90 Days or More Past Due		0	0	0
Total Past Due		0	0	322,000
Current		39,209,000	39,209,000	21,305,000
Total Loans Receivable		39,209,000	39,209,000	21,627,000
Total Loans Greater than 90 Days Past Due and Still Accruing		0	0	0
Loans with a specific allowance [Abstract]
Recorded Balance		0	0	785,000
Unpaid Principal Balance		0	0	2,960,000
Specific Allowance		0	0	43,000
Loans without a specific allowance [Abstract]
Recorded Balance		142,000	142,000	0
Unpaid Principal Balance		707,000	707,000	0
Total Loans [Abstract]
Recorded Balance		142,000	142,000	785,000
Unpaid Principal Balance		707,000	707,000	2,960,000
Average recorded investment and interest income recognized [Abstract]
Average investment in impaired loans			142,000	933,000	1,565,000
Interest income recognized			0	0	0
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans		142,000	142,000	785,000
Troubled Debt Restructuring [Abstract]
Troubled Debt Restructurings Balance		142,000	142,000	785,000
Recorded Balance of Troubled Debt Restructurings [Abstract]
Troubled Debt Restructurings Balance		142,000	142,000	785,000
Construction and land development | Pass [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		39,067,000	39,067,000	20,842,000
Construction and land development | Watch [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		0	0	0
Construction and land development | Substandard [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		142,000	142,000	785,000
Construction and land development | Doubtful [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		0	0	0
Farm loans
Loans Receivable Aging Analysis [Abstract]
30 to 59 Days Past Due		106,000	106,000	0
60 to 89 Days Past Due		0	0	0
90 Days or More Past Due		0	0	0
Total Past Due		106,000	106,000	0
Current		122,368,000	122,368,000	110,193,000
Total Loans Receivable		122,474,000	122,474,000	110,193,000
Total Loans Greater than 90 Days Past Due and Still Accruing		0	0	0
Loans with a specific allowance [Abstract]
Recorded Balance		430,000	430,000	0
Unpaid Principal Balance		430,000	430,000	0
Specific Allowance		0	0	0
Loans without a specific allowance [Abstract]
Recorded Balance		24,000	24,000	73,000
Unpaid Principal Balance		28,000	28,000	235,000
Total Loans [Abstract]
Recorded Balance		454,000	454,000	73,000
Unpaid Principal Balance		458,000	458,000	235,000
Average recorded investment and interest income recognized [Abstract]
Average investment in impaired loans			527,000	78,000	107,000
Interest income recognized			2,000	2,000	0
Loans Receivable, Modifications, Still Accruing Interest		232,000	232,000	44,000
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans		454,000	454,000	29,000
Recorded Balance of Troubled Debt Restructurings [Abstract]
Financing Receivable Modifications Performing Recorded Investment		0	0	44,000
Financing Receivables, Modifications during Period, Balance			$ 232,000	$ 44,000
Financing Receivables, Modifications during Period, Number	[1]		4	2
Farm loans | Pass [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		118,103,000	$ 118,103,000	$ 107,976,000
Farm loans | Watch [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		2,282,000	2,282,000	1,036,000
Farm loans | Substandard [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		2,089,000	2,089,000	1,181,000
Farm loans | Doubtful [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		0	0	0
1-4 Family residential properties
Loans Receivable Aging Analysis [Abstract]
30 to 59 Days Past Due		1,059,000	1,059,000	201,000
60 to 89 Days Past Due		742,000	742,000	224,000
90 Days or More Past Due		154,000	154,000	385,000
Total Past Due		1,955,000	1,955,000	810,000
Current		229,616,000	229,616,000	181,111,000
Total Loans Receivable		231,571,000	231,571,000	181,921,000
Total Loans Greater than 90 Days Past Due and Still Accruing		0	0	0
Loans with a specific allowance [Abstract]
Recorded Balance		0	0	67,000
Unpaid Principal Balance		0	0	134,000
Specific Allowance		0	0	0
Loans without a specific allowance [Abstract]
Recorded Balance		1,373,000	1,373,000	1,156,000
Unpaid Principal Balance		1,688,000	1,688,000	2,866,000
Total Loans [Abstract]
Recorded Balance		1,373,000	1,373,000	1,223,000
Unpaid Principal Balance		1,688,000	1,688,000	3,000,000
Average recorded investment and interest income recognized [Abstract]
Average investment in impaired loans			1,440,000	1,276,000	1,248,000
Interest income recognized			14,000	12,000	5,000
Loans Receivable, Modifications, Still Accruing Interest		397,000	397,000	345,000
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans		975,000	975,000	878,000
Troubled Debt Restructuring [Abstract]
Troubled Debt Restructurings Balance		515,000	515,000	503,000
Recorded Balance of Troubled Debt Restructurings [Abstract]
Troubled Debt Restructurings Balance		515,000	515,000	503,000
Financing Receivable Modifications Performing Recorded Investment		397,000	397,000	345,000
Financing Receivables, Modifications during Period, Balance			$ 131,000	$ 250,000
Financing Receivables, Modifications during Period, Number	[1]		5	4
1-4 Family residential properties | Pass [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		224,552,000	$ 224,552,000	$ 177,764,000
1-4 Family residential properties | Watch [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		1,454,000	1,454,000	1,187,000
1-4 Family residential properties | Substandard [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		5,565,000	5,565,000	2,970,000
1-4 Family residential properties | Doubtful [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		0	0	0
Multifamily residential properties
Loans Receivable Aging Analysis [Abstract]
30 to 59 Days Past Due		0	0	0
60 to 89 Days Past Due		0	0	0
90 Days or More Past Due		0	0	0
Total Past Due		0	0	0
Current		45,740,000	45,740,000	53,129,000
Total Loans Receivable		45,740,000	45,740,000	53,129,000
Total Loans Greater than 90 Days Past Due and Still Accruing		0	0	0
Loans with a specific allowance [Abstract]
Recorded Balance		316,000	316,000	0
Unpaid Principal Balance		316,000	316,000	0
Specific Allowance		0	0	0
Loans without a specific allowance [Abstract]
Recorded Balance		1,000	1,000	0
Unpaid Principal Balance		1,000	1,000	0
Total Loans [Abstract]
Recorded Balance		317,000	317,000	0
Unpaid Principal Balance		317,000	317,000	0
Average recorded investment and interest income recognized [Abstract]
Average investment in impaired loans			323,000	0	0
Interest income recognized			0	0	0
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans		317,000	317,000	0
Multifamily residential properties | Pass [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		45,180,000	45,180,000	52,793,000
Multifamily residential properties | Watch [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		243,000	243,000	0
Multifamily residential properties | Substandard [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		317,000	317,000	336,000
Multifamily residential properties | Doubtful [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		0	0	0
Commercial real estate
Loans Receivable Aging Analysis [Abstract]
30 to 59 Days Past Due		251,000	251,000	60,000
60 to 89 Days Past Due		67,000	67,000	32,000
90 Days or More Past Due		31,000	31,000	945,000
Total Past Due		349,000	349,000	1,037,000
Current		408,823,000	408,823,000	378,567,000
Total Loans Receivable		409,172,000	409,172,000	379,604,000
Total Loans Greater than 90 Days Past Due and Still Accruing		0	0	0
Loans with a specific allowance [Abstract]
Recorded Balance		0	0	472,000
Unpaid Principal Balance		0	0	986,000
Specific Allowance		0	0	136,000
Loans without a specific allowance [Abstract]
Recorded Balance		304,000	304,000	1,640,000
Unpaid Principal Balance		325,000	325,000	3,808,000
Total Loans [Abstract]
Recorded Balance		304,000	304,000	2,112,000
Unpaid Principal Balance		325,000	325,000	4,794,000
Average recorded investment and interest income recognized [Abstract]
Average investment in impaired loans			310,000	2,205,000	2,895,000
Interest income recognized			2,000	2,000	3,000
Loans Receivable, Modifications, Still Accruing Interest		36,000	36,000	37,000
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans		269,000	269,000	2,074,000
Troubled Debt Restructuring [Abstract]
Troubled Debt Restructurings Balance		124,000	124,000	1,283,000
Recorded Balance of Troubled Debt Restructurings [Abstract]
Troubled Debt Restructurings Balance		124,000	124,000	1,283,000
Financing Receivable Modifications Performing Recorded Investment		36,000	36,000	37,000
Financing Receivables, Modifications during Period, Balance			$ 33,000	$ 501,000
Financing Receivables, Modifications during Period, Number	[1]		1	1
Commercial real estate | Pass [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		386,769,000	$ 386,769,000	$ 357,873,000
Commercial real estate | Watch [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		10,498,000	10,498,000	18,817,000
Commercial real estate | Substandard [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		11,905,000	11,905,000	2,914,000
Commercial real estate | Doubtful [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		0	0	0
Loans secured by real estate
Loans Receivable Aging Analysis [Abstract]
30 to 59 Days Past Due		1,416,000	1,416,000	558,000
60 to 89 Days Past Due		809,000	809,000	281,000
90 Days or More Past Due		185,000	185,000	1,330,000
Total Past Due		2,410,000	2,410,000	2,169,000
Current		845,756,000	845,756,000	744,305,000
Total Loans Receivable		848,166,000	848,166,000	746,474,000
Total Loans Greater than 90 Days Past Due and Still Accruing		0	0	0
Loans with a specific allowance [Abstract]
Recorded Balance		746,000	746,000	1,324,000
Unpaid Principal Balance		746,000	746,000	4,080,000
Specific Allowance		0	0	179,000
Loans without a specific allowance [Abstract]
Recorded Balance		1,844,000	1,844,000	2,869,000
Unpaid Principal Balance		2,749,000	2,749,000	6,909,000
Total Loans [Abstract]
Recorded Balance		2,590,000	2,590,000	4,193,000
Unpaid Principal Balance		3,495,000	3,495,000	10,989,000
Average recorded investment and interest income recognized [Abstract]
Average investment in impaired loans			2,742,000	4,492,000	5,815,000
Interest income recognized			18,000	16,000	8,000
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans		2,157,000	2,157,000	3,766,000
Troubled Debt Restructuring [Abstract]
Troubled Debt Restructurings Balance		1,013,000	1,013,000	2,615,000
Recorded Balance of Troubled Debt Restructurings [Abstract]
Troubled Debt Restructurings Balance		1,013,000	1,013,000	2,615,000
Financing Receivable Modifications Performing Recorded Investment		433,000	433,000	426,000
Financing Receivables, Modifications during Period, Balance			$ 396,000	$ 795,000
Financing Receivables, Modifications during Period, Number			10	7
Agricultural loans
Loans Receivable Aging Analysis [Abstract]
30 to 59 Days Past Due		65,000	$ 65,000	$ 16,000
60 to 89 Days Past Due		74,000	74,000	20,000
90 Days or More Past Due		0	0	0
Total Past Due		139,000	139,000	36,000
Current		75,747,000	75,747,000	68,262,000
Total Loans Receivable		75,886,000	75,886,000	68,298,000
Total Loans Greater than 90 Days Past Due and Still Accruing		0	0	0
Loans with a specific allowance [Abstract]
Recorded Balance		0	0	0
Unpaid Principal Balance		0	0	0
Specific Allowance		0	0	0
Loans without a specific allowance [Abstract]
Recorded Balance		79,000	79,000	0
Unpaid Principal Balance		79,000	79,000	0
Total Loans [Abstract]
Recorded Balance		79,000	79,000	0
Unpaid Principal Balance		79,000	79,000	0
Average recorded investment and interest income recognized [Abstract]
Average investment in impaired loans			82,000	0	16,000
Interest income recognized			0	0	1,000
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans		79,000	79,000	0
Agricultural loans | Pass [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		75,437,000	75,437,000	67,619,000
Agricultural loans | Watch [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		210,000	210,000	0
Agricultural loans | Substandard [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		239,000	239,000	679,000
Agricultural loans | Doubtful [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		0	0	0
Commercial and industrial loans
Loans Receivable Aging Analysis [Abstract]
30 to 59 Days Past Due		65,000	65,000	228,000
60 to 89 Days Past Due		476,000	476,000	10,000
90 Days or More Past Due		196,000	196,000	98,000
Total Past Due		737,000	737,000	336,000
Current		304,323,000	304,323,000	223,444,000
Total Loans Receivable		305,060,000	305,060,000	223,780,000
Total Loans Greater than 90 Days Past Due and Still Accruing		0	0	0
Loans with a specific allowance [Abstract]
Recorded Balance		405,000	405,000	83,000
Unpaid Principal Balance		405,000	405,000	181,000
Specific Allowance		134,000	134,000	84,000
Loans without a specific allowance [Abstract]
Recorded Balance		670,000	670,000	249,000
Unpaid Principal Balance		932,000	932,000	933,000
Total Loans [Abstract]
Recorded Balance		1,075,000	1,075,000	332,000
Unpaid Principal Balance		1,337,000	1,337,000	1,114,000
Average recorded investment and interest income recognized [Abstract]
Average investment in impaired loans			1,569,000	429,000	1,240,000
Interest income recognized			8,000	0	10,000
Loans Receivable, Modifications, Still Accruing Interest		147,000	147,000
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans		928,000	928,000	332,000
Troubled Debt Restructuring [Abstract]
Troubled Debt Restructurings Balance		491,000	491,000	236,000
Recorded Balance of Troubled Debt Restructurings [Abstract]
Troubled Debt Restructurings Balance		491,000	491,000	236,000
Financing Receivable Modifications Performing Recorded Investment		147,000	147,000	0
Financing Receivables, Modifications during Period, Balance			$ 375,000	$ 0
Financing Receivables, Modifications during Period, Number	[1]		5	0
Commercial and industrial loans | Pass [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		298,633,000	$ 298,633,000	$ 218,193,000
Commercial and industrial loans | Watch [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		4,686,000	4,686,000	4,647,000
Commercial and industrial loans | Substandard [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		1,741,000	1,741,000	940,000
Commercial and industrial loans | Doubtful [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		0	0	0
Consumer loans
Loans Receivable Aging Analysis [Abstract]
30 to 59 Days Past Due		137,000	137,000	331,000
60 to 89 Days Past Due		42,000	42,000	10,000
90 Days or More Past Due		13,000	13,000	5,000
Total Past Due		192,000	192,000	346,000
Current		41,387,000	41,387,000	14,772,000
Total Loans Receivable		41,579,000	41,579,000	15,118,000
Total Loans Greater than 90 Days Past Due and Still Accruing		0	0	0
Loans with a specific allowance [Abstract]
Recorded Balance		23,000	23,000	0
Unpaid Principal Balance		23,000	23,000	0
Specific Allowance		0	0	0
Loans without a specific allowance [Abstract]
Recorded Balance		242,000	242,000	15,000
Unpaid Principal Balance		256,000	256,000	60,000
Total Loans [Abstract]
Recorded Balance		265,000	265,000	15,000
Unpaid Principal Balance		279,000	279,000	60,000
Average recorded investment and interest income recognized [Abstract]
Average investment in impaired loans			319,000	25,000	47,000
Interest income recognized			2,000	1,000	12,000
Loans Receivable, Modifications, Still Accruing Interest		21,000	21,000	9,000
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans		248,000	248,000	7,000
Troubled Debt Restructuring [Abstract]
Troubled Debt Restructurings Balance		239,000	239,000	9,000
Recorded Balance of Troubled Debt Restructurings [Abstract]
Troubled Debt Restructurings Balance		239,000	239,000	9,000
Financing Receivable Modifications Performing Recorded Investment		21,000	21,000	9,000
Financing Receivables, Modifications during Period, Balance			$ 233,000	$ 0
Financing Receivables, Modifications during Period, Number	[1]		4	0
Consumer loans | Pass [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		41,278,000	$ 41,278,000	$ 15,105,000
Consumer loans | Watch [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		0	0	9,000
Consumer loans | Substandard [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		301,000	301,000	4,000
Consumer loans | Doubtful [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		0	0	0
All other loans
Loans Receivable Aging Analysis [Abstract]
30 to 59 Days Past Due		0	0	0
60 to 89 Days Past Due		0	0	0
90 Days or More Past Due		0	0	0
Total Past Due		0	0	0
Current		11,198,000	11,198,000	8,736,000
Total Loans Receivable		11,198,000	11,198,000	8,736,000
Total Loans Greater than 90 Days Past Due and Still Accruing		0	0	0
Loans with a specific allowance [Abstract]
Recorded Balance		0	0	0
Unpaid Principal Balance		0	0	0
Specific Allowance		0	0	0
Loans without a specific allowance [Abstract]
Recorded Balance		0	0	0
Unpaid Principal Balance		0	0	0
Total Loans [Abstract]
Recorded Balance		0	0	0
Unpaid Principal Balance		0	0	0
Average recorded investment and interest income recognized [Abstract]
Average investment in impaired loans			0	0	0
Interest income recognized			0	0	$ 0
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans		0	0	0
All other loans | Pass [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		11,198,000	11,198,000	8,736,000
All other loans | Watch [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		0	0	0
All other loans | Substandard [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		0	0	0
All other loans | Doubtful [Member]
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable		$ 0	$ 0	$ 0

[1] Type of modifications:(a) Reduction of stated interest rate of loan(b) Change in payment terms(c) Extension of maturity date(d) Permanent reduction of the recorded investment