Loans and Allowance for Loan Losses, Part II (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Minimum Balance Of Loans For Which Credit Quality Analysis Is Performed	$ 100,000		$ 100,000
Loans Receivable Aging Analysis [Abstract]
30-59 days Past Due	1,085,000		1,085,000		2,737,000
60-89 days Past Due	988,000		988,000		1,303,000
90 Days or More Past Due	1,205,000		1,205,000		2,204,000
Total Past Due	3,278,000		3,278,000		6,244,000
Current	912,535,000		912,535,000		904,821,000
Total Loans Receivable	915,813,000		915,813,000		911,065,000
Total Loans 90 days & 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			not less than six months
Loans with a specific allowance [Abstract]
Recorded Balance	3,051,000		3,051,000		2,060,000
Unpaid Principal Balance	3,752,000		3,752,000		2,562,000
Specific Allowance	439,000		439,000		511,000
Loans without a specific allowance [Abstract]
Recorded Balance	3,785,000		3,785,000		5,533,000
Unpaid Principal Balance	4,808,000		4,808,000		6,794,000
Total Loans [Abstract]
Recorded Balance	6,836,000		6,836,000		7,593,000
Unpaid Principal Balance	8,560,000		8,560,000		9,356,000
Average recorded investment and interest income recognized [Abstract]
Average investment in impaired loans	6,993,000	6,937,000	7,259,000	6,935,000
Interest income recognized	2,000	10,000	3,000	21,000
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans	6,711,000		6,711,000		7,573,000
Interest Lost on Nonaccrual Loans			72,000	130,000
Troubled Debt Restructuring [Abstract]
Troubled Debt Restructurings Balance	3,285,000		3,285,000		3,339,000
Troubled Debt Restructuring, Allowance	352,000		352,000		295,000
Financing Receivable Modifications Performing Recorded Investment	125,000		125,000		20,000
Recorded Balance of Troubled Debt Restructurings [Abstract]
Financing Receivables, Modifications during Period, Number			5	11
Financing Receivables, Modifications during Period, Balance			162,000	1,420,000
Subsequent Default, Number of Days Past Due			90 days
Pass
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	869,384,000		869,384,000		865,059,000
Watch
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	36,308,000		36,308,000		31,994,000
Substandard
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	10,121,000		10,121,000		14,012,000
Doubtful
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	0		0		0
Construction and land development
Loans Receivable Aging Analysis [Abstract]
30-59 days Past Due	0		0		0
60-89 days Past Due	0		0		53,000
90 Days or More Past Due	13,000		13,000		0
Total Past Due	13,000		13,000		53,000
Current	22,589,000		22,589,000		31,288,000
Total Loans Receivable	22,602,000		22,602,000		31,341,000
Total Loans 90 days & Accruing	0		0		0
Loans with a specific allowance [Abstract]
Recorded Balance	1,408,000		1,408,000		1,114,000
Unpaid Principal Balance	2,109,000		2,109,000		1,529,000
Specific Allowance	181,000		181,000		295,000
Loans without a specific allowance [Abstract]
Recorded Balance	13,000		13,000		408,000
Unpaid Principal Balance	21,000		21,000		694,000
Total Loans [Abstract]
Recorded Balance	1,421,000		1,421,000		1,522,000
Unpaid Principal Balance	2,130,000		2,130,000		2,223,000
Average recorded investment and interest income recognized [Abstract]
Average investment in impaired loans	1,425,000	1,014,000	1,445,000	1,014,000
Interest income recognized	0	0	0	0
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans	1,421,000		1,421,000		1,522,000
Troubled Debt Restructuring [Abstract]
Troubled Debt Restructurings Balance	1,409,000		1,409,000		1,522,000
Recorded Balance of Troubled Debt Restructurings [Abstract]
Financing Receivables, Modifications during Period, Number			0	3
Financing Receivables, Modifications during Period, Balance			0	1,014,000
Construction and land development | Pass
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	18,737,000		18,737,000		27,217,000
Construction and land development | Watch
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	2,099,000		2,099,000		2,135,000
Construction and land development | Substandard
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	1,766,000		1,766,000		1,989,000
Construction and land development | Doubtful
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	0		0		0
Agricultural real estate
Loans Receivable Aging Analysis [Abstract]
30-59 days Past Due	153,000		153,000		592,000
60-89 days Past Due	0		0		0
90 Days or More Past Due	103,000		103,000		293,000
Total Past Due	256,000		256,000		885,000
Current	95,021,000		95,021,000		85,386,000
Total Loans Receivable	95,277,000		95,277,000		86,271,000
Total Loans 90 days & 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	216,000		216,000		418,000
Unpaid Principal Balance	226,000		226,000		429,000
Total Loans [Abstract]
Recorded Balance	216,000		216,000		418,000
Unpaid Principal Balance	226,000		226,000		429,000
Average recorded investment and interest income recognized [Abstract]
Average investment in impaired loans	216,000	206,000	217,000	206,000
Interest income recognized	0	0	0	0
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans	216,000		216,000		418,000
Agricultural real estate | Pass
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	93,283,000		93,283,000		82,516,000
Agricultural real estate | Watch
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	1,225,000		1,225,000		2,662,000
Agricultural real estate | Substandard
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	769,000		769,000		1,093,000
Agricultural real estate | Doubtful
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	0		0		0
1-4 Family residential properties
Loans Receivable Aging Analysis [Abstract]
30-59 days Past Due	523,000		523,000		1,351,000
60-89 days Past Due	310,000		310,000		40,000
90 Days or More Past Due	478,000		478,000		944,000
Total Past Due	1,311,000		1,311,000		2,335,000
Current	186,944,000		186,944,000		184,163,000
Total Loans Receivable	188,255,000		188,255,000		186,498,000
Total Loans 90 days & Accruing	0		0		0
Loans with a specific allowance [Abstract]
Recorded Balance	0		0		636,000
Unpaid Principal Balance	0		0		723,000
Specific Allowance	0		0		162,000
Loans without a specific allowance [Abstract]
Recorded Balance	1,191,000		1,191,000		1,269,000
Unpaid Principal Balance	1,796,000		1,796,000		1,792,000
Total Loans [Abstract]
Recorded Balance	1,191,000		1,191,000		1,905,000
Unpaid Principal Balance	1,796,000		1,796,000		2,515,000
Average recorded investment and interest income recognized [Abstract]
Average investment in impaired loans	1,283,000	1,621,000	1,414,000	1,632,000
Interest income recognized	1,000	0	2,000	0
Loans Receivable, Modifications, Still Accruing Interest	103,000	7,000	103,000	7,000
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans	1,088,000		1,088,000		1,899,000
Troubled Debt Restructuring [Abstract]
Troubled Debt Restructurings Balance	511,000		511,000		445,000
Financing Receivable Modifications Performing Recorded Investment	103,000		103,000		6,000
Recorded Balance of Troubled Debt Restructurings [Abstract]
Financing Receivables, Modifications during Period, Number			3	2
Financing Receivables, Modifications during Period, Balance			98,000	94,000
1-4 Family residential properties | Pass
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	185,885,000		185,885,000		183,880,000
1-4 Family residential properties | Watch
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	275,000		275,000		424,000
1-4 Family residential properties | Substandard
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	2,095,000		2,095,000		2,194,000
1-4 Family residential properties | Doubtful
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	0		0		0
Multifamily residential properties
Loans Receivable Aging Analysis [Abstract]
30-59 days Past Due	0		0		0
60-89 days Past Due	0		0		0
90 Days or More Past Due	0		0		0
Total Past Due	0		0		0
Current	44,207,000		44,207,000		44,863,000
Total Loans Receivable	44,207,000		44,207,000		44,863,000
Total Loans 90 days & 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	0
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans	0		0		0
Multifamily residential properties | Pass
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	44,207,000		44,207,000		44,863,000
Multifamily residential properties | Watch
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	0		0		0
Multifamily residential properties | Substandard
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	0		0		0
Multifamily residential properties | Doubtful
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	0		0		0
Commercial real estate
Loans Receivable Aging Analysis [Abstract]
30-59 days Past Due	195,000		195,000		262,000
60-89 days Past Due	388,000		388,000		911,000
90 Days or More Past Due	215,000		215,000		255,000
Total Past Due	798,000		798,000		1,428,000
Current	334,006,000		334,006,000		314,894,000
Total Loans Receivable	334,804,000		334,804,000		316,322,000
Total Loans 90 days & Accruing	0		0		0
Loans with a specific allowance [Abstract]
Recorded Balance	819,000		819,000		0
Unpaid Principal Balance	819,000		819,000		0
Specific Allowance	89,000		89,000		0
Loans without a specific allowance [Abstract]
Recorded Balance	1,515,000		1,515,000		2,063,000
Unpaid Principal Balance	1,575,000		1,575,000		2,253,000
Total Loans [Abstract]
Recorded Balance	2,334,000		2,334,000		2,063,000
Unpaid Principal Balance	2,394,000		2,394,000		2,253,000
Average recorded investment and interest income recognized [Abstract]
Average investment in impaired loans	2,353,000	2,437,000	2,389,000	2,349,000
Interest income recognized	0	7,000	0	14,000
Loans Receivable, Modifications, Still Accruing Interest		389,000		389,000
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans	2,334,000		2,334,000		2,063,000
Troubled Debt Restructuring [Abstract]
Troubled Debt Restructurings Balance	898,000		898,000		950,000
Financing Receivable Modifications Performing Recorded Investment	0		0		0
Recorded Balance of Troubled Debt Restructurings [Abstract]
Financing Receivables, Modifications during Period, Number			0	5
Financing Receivables, Modifications during Period, Balance			0	296,000
Commercial real estate | Pass
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	308,675,000		308,675,000		287,794,000
Commercial real estate | Watch
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	22,636,000		22,636,000		24,213,000
Commercial real estate | Substandard
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	3,493,000		3,493,000		4,315,000
Commercial real estate | Doubtful
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	0		0		0
Agricultural loans
Loans Receivable Aging Analysis [Abstract]
30-59 days Past Due	50,000		50,000		0
60-89 days Past Due	0		0		0
90 Days or More Past Due	209,000		209,000		620,000
Total Past Due	259,000		259,000		620,000
Current	51,682,000		51,682,000		60,394,000
Total Loans Receivable	51,941,000		51,941,000		61,014,000
Total Loans 90 days & Accruing	0		0		0
Loans with a specific allowance [Abstract]
Recorded Balance	0		0		310,000
Unpaid Principal Balance	0		0		310,000
Specific Allowance	0		0		54,000
Loans without a specific allowance [Abstract]
Recorded Balance	209,000		209,000		620,000
Unpaid Principal Balance	209,000		209,000		1,568,000
Total Loans [Abstract]
Recorded Balance	209,000		209,000		930,000
Unpaid Principal Balance	209,000		209,000		1,878,000
Average recorded investment and interest income recognized [Abstract]
Average investment in impaired loans	229,000	864,000	253,000	883,000
Interest income recognized	0	0	0	0
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans	209,000		209,000		930,000
Agricultural loans | Pass
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	51,111,000		51,111,000		56,899,000
Agricultural loans | Watch
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	0		0		958,000
Agricultural loans | Substandard
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	830,000		830,000		3,157,000
Agricultural loans | Doubtful
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	0		0		0
Commercial and industrial loans
Loans Receivable Aging Analysis [Abstract]
30-59 days Past Due	83,000		83,000		413,000
60-89 days Past Due	254,000		254,000		275,000
90 Days or More Past Due	163,000		163,000		53,000
Total Past Due	500,000		500,000		741,000
Current	152,575,000		152,575,000		159,558,000
Total Loans Receivable	153,075,000		153,075,000		160,299,000
Total Loans 90 days & Accruing	0		0		0
Loans with a specific allowance [Abstract]
Recorded Balance	812,000		812,000		0
Unpaid Principal Balance	812,000		812,000		0
Specific Allowance	167,000		167,000		0
Loans without a specific allowance [Abstract]
Recorded Balance	597,000		597,000		704,000
Unpaid Principal Balance	898,000		898,000		0
Total Loans [Abstract]
Recorded Balance	1,409,000		1,409,000		704,000
Unpaid Principal Balance	1,710,000		1,710,000		0
Average recorded investment and interest income recognized [Abstract]
Average investment in impaired loans	1,430,000	780,000	1,482,000	834,000
Interest income recognized	0	3,000	0	7,000
Loans Receivable, Modifications, Still Accruing Interest		304,000		304,000
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans	1,409,000		1,409,000		704,000
Troubled Debt Restructuring [Abstract]
Troubled Debt Restructurings Balance	446,000		446,000		408,000
Financing Receivable Modifications Performing Recorded Investment	0		0		0
Recorded Balance of Troubled Debt Restructurings [Abstract]
Financing Receivables, Modifications during Period, Number			1	1
Financing Receivables, Modifications during Period, Balance			56,000	16,000
Commercial and industrial loans | Pass
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	141,874,000		141,874,000		157,461,000
Commercial and industrial loans | Watch
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	10,073,000		10,073,000		1,588,000
Commercial and industrial loans | Substandard
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	1,128,000		1,128,000		1,250,000
Commercial and industrial loans | Doubtful
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	0		0		0
Consumer loans
Loans Receivable Aging Analysis [Abstract]
30-59 days Past Due	81,000		81,000		119,000
60-89 days Past Due	36,000		36,000		24,000
90 Days or More Past Due	24,000		24,000		39,000
Total Past Due	141,000		141,000		182,000
Current	15,673,000		15,673,000		16,082,000
Total Loans Receivable	15,814,000		15,814,000		16,264,000
Total Loans 90 days & Accruing	0		0		0
Loans with a specific allowance [Abstract]
Recorded Balance	12,000		12,000		0
Unpaid Principal Balance	12,000		12,000		0
Specific Allowance	2,000		2,000		0
Loans without a specific allowance [Abstract]
Recorded Balance	44,000		44,000		51,000
Unpaid Principal Balance	83,000		83,000		58,000
Total Loans [Abstract]
Recorded Balance	56,000		56,000		51,000
Unpaid Principal Balance	95,000		95,000		58,000
Average recorded investment and interest income recognized [Abstract]
Average investment in impaired loans	57,000	15,000	59,000	17,000
Interest income recognized	1,000	0	1,000	0
Loans Receivable, Modifications, Still Accruing Interest	22,000		22,000
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans	34,000		34,000		37,000
Troubled Debt Restructuring [Abstract]
Troubled Debt Restructurings Balance	21,000		21,000		14,000
Financing Receivable Modifications Performing Recorded Investment	22,000		22,000		14,000
Recorded Balance of Troubled Debt Restructurings [Abstract]
Financing Receivables, Modifications during Period, Number			1	0
Financing Receivables, Modifications during Period, Balance			8,000	0
Consumer loans | Pass
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	15,774,000		15,774,000		16,236,000
Consumer loans | Watch
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	0		0		14,000
Consumer loans | Substandard
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	40,000		40,000		14,000
Consumer loans | Doubtful
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	0		0		0
All other loans
Loans Receivable Aging Analysis [Abstract]
30-59 days Past Due	0		0		0
60-89 days Past Due	0		0		0
90 Days or More Past Due	0		0		0
Total Past Due	0		0		0
Current	9,838,000		9,838,000		8,193,000
Total Loans Receivable	9,838,000		9,838,000		8,193,000
Total Loans 90 days & 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	0
Interest income recognized	0	0	0	0
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans	0		0		0
All other loans | Pass
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	9,838,000		9,838,000		8,193,000
All other loans | Watch
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	0		0		0
All other loans | Substandard
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	0		0		0
All other loans | Doubtful
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	0		0		0
Loans secured by real estate
Loans Receivable Aging Analysis [Abstract]
30-59 days Past Due	871,000		871,000		2,205,000
60-89 days Past Due	698,000		698,000		1,004,000
90 Days or More Past Due	809,000		809,000		1,492,000
Total Past Due	2,378,000		2,378,000		4,701,000
Current	682,767,000		682,767,000		660,594,000
Total Loans Receivable	685,145,000		685,145,000		665,295,000
Total Loans 90 days & Accruing	0		0		0
Loans with a specific allowance [Abstract]
Recorded Balance	2,227,000		2,227,000		1,750,000
Unpaid Principal Balance	2,928,000		2,928,000		2,252,000
Specific Allowance	270,000		270,000		457,000
Loans without a specific allowance [Abstract]
Recorded Balance	2,935,000		2,935,000		4,158,000
Unpaid Principal Balance	3,618,000		3,618,000		5,168,000
Total Loans [Abstract]
Recorded Balance	5,162,000		5,162,000		5,908,000
Unpaid Principal Balance	6,546,000		6,546,000		7,420,000
Average recorded investment and interest income recognized [Abstract]
Average investment in impaired loans	5,277,000	5,278,000	5,465,000	5,201,000
Interest income recognized	1,000	7,000	2,000	14,000
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans	5,059,000		5,059,000		5,902,000
Troubled Debt Restructuring [Abstract]
Troubled Debt Restructurings Balance	2,818,000		2,818,000		2,917,000
Financing Receivable Modifications Performing Recorded Investment	103,000		103,000		6,000
Recorded Balance of Troubled Debt Restructurings [Abstract]
Financing Receivables, Modifications during Period, Number			3	10
Financing Receivables, Modifications during Period, Balance			$ 98,000	$ 1,404,000