Loans and Allowance for Loan Losses, Part II (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 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	914,000		914,000		2,737,000
60-89 days Past Due	816,000		816,000		1,303,000
90 Days or More Past Due	871,000		871,000		2,204,000
Total Past Due	2,601,000		2,601,000		6,244,000
Current	940,490,000		940,490,000		904,821,000
Total Loans Receivable	943,091,000		943,091,000		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	3,084,000		3,084,000		2,060,000
Unpaid Principal Balance	3,785,000		3,785,000		2,562,000
Specific Allowance	540,000		540,000		511,000
Loans without a specific allowance [Abstract]
Recorded Balance	3,927,000		3,927,000		5,533,000
Unpaid Principal Balance	4,887,000		4,887,000		6,794,000
Total Loans [Abstract]
Recorded Balance	7,011,000		7,011,000		7,593,000
Unpaid Principal Balance	8,672,000		8,672,000		9,356,000
Average recorded investment and interest income recognized [Abstract]
Average investment in impaired loans	7,129,000	8,106,000	7,659,000	8,198,000
Interest income recognized	3,000	10,000	6,000	32,000
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans	6,880,000		6,880,000		7,573,000
Interest Lost on Nonaccrual Loans			109,000	165,000
Troubled Debt Restructuring [Abstract]
Troubled Debt Restructurings Balance	3,267,000		3,267,000		3,339,000
Troubled Debt Restructuring, Allowance	344,000		344,000		295,000
Financing Receivable Modifications Performing Recorded Investment	131,000		131,000		20,000
Recorded Balance of Troubled Debt Restructurings [Abstract]
Financing Receivables, Modifications during Period, Number			9	12
Financing Receivables, Modifications during Period, Balance			603,000	2,135,000
Subsequent Default, Number of Days Past Due			90 days
Pass
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	902,551,000		902,551,000		865,059,000
Watch
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	19,763,000		19,763,000		31,994,000
Substandard
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	20,777,000		20,777,000		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	20,045,000		20,045,000		31,288,000
Total Loans Receivable	20,058,000		20,058,000		31,341,000
Total Loans 90 days & Accruing	0		0		0
Loans with a specific allowance [Abstract]
Recorded Balance	1,735,000		1,735,000		1,114,000
Unpaid Principal Balance	2,436,000		2,436,000		1,529,000
Specific Allowance	172,000		172,000		295,000
Loans without a specific allowance [Abstract]
Recorded Balance	13,000		13,000		408,000
Unpaid Principal Balance	20,000		20,000		694,000
Total Loans [Abstract]
Recorded Balance	1,748,000		1,748,000		1,522,000
Unpaid Principal Balance	2,456,000		2,456,000		2,223,000
Average recorded investment and interest income recognized [Abstract]
Average investment in impaired loans	1,753,000	1,750,000	1,775,000	1,736,000
Interest income recognized	0	0	0	0
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans	1,748,000		1,748,000		1,522,000
Troubled Debt Restructuring [Abstract]
Troubled Debt Restructurings Balance	1,735,000		1,735,000		1,522,000
Recorded Balance of Troubled Debt Restructurings [Abstract]
Financing Receivables, Modifications during Period, Number			1	4
Financing Receivables, Modifications during Period, Balance			357,000	1,553,000
Construction and land development | Pass
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	18,323,000		18,323,000		27,217,000
Construction and land development | Watch
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	0		0		2,135,000
Construction and land development | Substandard
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	1,735,000		1,735,000		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	48,000		48,000		592,000
60-89 days Past Due	0		0		0
90 Days or More Past Due	0		0		293,000
Total Past Due	48,000		48,000		885,000
Current	101,806,000		101,806,000		85,386,000
Total Loans Receivable	101,854,000		101,854,000		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	235,000		235,000		418,000
Unpaid Principal Balance	244,000		244,000		429,000
Total Loans [Abstract]
Recorded Balance	235,000		235,000		418,000
Unpaid Principal Balance	244,000		244,000		429,000
Average recorded investment and interest income recognized [Abstract]
Average investment in impaired loans	238,000	199,000	238,000	199,000
Interest income recognized	0	0	0	0
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans	235,000		235,000		418,000
Agricultural real estate | Pass
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	100,824,000		100,824,000		82,516,000
Agricultural real estate | Watch
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	238,000		238,000		2,662,000
Agricultural real estate | Substandard
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	792,000		792,000		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	438,000		438,000		1,351,000
60-89 days Past Due	271,000		271,000		40,000
90 Days or More Past Due	443,000		443,000		944,000
Total Past Due	1,152,000		1,152,000		2,335,000
Current	188,288,000		188,288,000		184,163,000
Total Loans Receivable	189,440,000		189,440,000		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	1,003,000		1,003,000		1,269,000
Unpaid Principal Balance	1,540,000		1,540,000		1,792,000
Total Loans [Abstract]
Recorded Balance	1,003,000		1,003,000		1,905,000
Unpaid Principal Balance	1,540,000		1,540,000		2,515,000
Average recorded investment and interest income recognized [Abstract]
Average investment in impaired loans	1,007,000	1,972,000	1,172,000	1,982,000
Interest income recognized	2,000	0	4,000	0
Loans Receivable, Modifications, Still Accruing Interest	102,000	6,000	102,000	6,000
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans	901,000		901,000		1,899,000
Troubled Debt Restructuring [Abstract]
Troubled Debt Restructurings Balance	239,000		239,000		445,000
Financing Receivable Modifications Performing Recorded Investment	102,000		102,000		6,000
Recorded Balance of Troubled Debt Restructurings [Abstract]
Financing Receivables, Modifications during Period, Number			4	2
Financing Receivables, Modifications during Period, Balance			176,000	94,000
1-4 Family residential properties | Pass
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	187,245,000		187,245,000		183,880,000
1-4 Family residential properties | Watch
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	644,000		644,000		424,000
1-4 Family residential properties | Substandard
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	1,551,000		1,551,000		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	42,342,000		42,342,000		44,863,000
Total Loans Receivable	42,342,000		42,342,000		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	42,342,000		42,342,000		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	83,000		83,000		262,000
60-89 days Past Due	355,000		355,000		911,000
90 Days or More Past Due	61,000		61,000		255,000
Total Past Due	499,000		499,000		1,428,000
Current	342,081,000		342,081,000		314,894,000
Total Loans Receivable	342,580,000		342,580,000		316,322,000
Total Loans 90 days & Accruing	0		0		0
Loans with a specific allowance [Abstract]
Recorded Balance	1,255,000		1,255,000		0
Unpaid Principal Balance	1,255,000		1,255,000		0
Specific Allowance	274,000		274,000		0
Loans without a specific allowance [Abstract]
Recorded Balance	1,672,000		1,672,000		2,063,000
Unpaid Principal Balance	1,731,000		1,731,000		2,253,000
Total Loans [Abstract]
Recorded Balance	2,927,000		2,927,000		2,063,000
Unpaid Principal Balance	2,986,000		2,986,000		2,253,000
Average recorded investment and interest income recognized [Abstract]
Average investment in impaired loans	2,939,000	2,299,000	2,985,000	2,319,000
Interest income recognized	0	7,000	0	21,000
Loans Receivable, Modifications, Still Accruing Interest		388,000		388,000
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans	2,927,000		2,927,000		2,063,000
Troubled Debt Restructuring [Abstract]
Troubled Debt Restructurings Balance	878,000		878,000		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	1
Financing Receivables, Modifications during Period, Balance			0	289,000
Commercial real estate | Pass
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	317,846,000		317,846,000		287,794,000
Commercial real estate | Watch
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	17,930,000		17,930,000		24,213,000
Commercial real estate | Substandard
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	6,804,000		6,804,000		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	0		0		0
60-89 days Past Due	107,000		107,000		0
90 Days or More Past Due	209,000		209,000		620,000
Total Past Due	316,000		316,000		620,000
Current	60,273,000		60,273,000		60,394,000
Total Loans Receivable	60,589,000		60,589,000		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	209,000	837,000	238,000	867,000
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	59,551,000		59,551,000		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	1,038,000		1,038,000		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	297,000		297,000		413,000
60-89 days Past Due	62,000		62,000		275,000
90 Days or More Past Due	106,000		106,000		53,000
Total Past Due	465,000		465,000		741,000
Current	159,263,000		159,263,000		159,558,000
Total Loans Receivable	159,728,000		159,728,000		160,299,000
Total Loans 90 days & Accruing	0		0		0
Loans with a specific allowance [Abstract]
Recorded Balance	94,000		94,000		0
Unpaid Principal Balance	94,000		94,000		0
Specific Allowance	94,000		94,000		0
Loans without a specific allowance [Abstract]
Recorded Balance	720,000		720,000		704,000
Unpaid Principal Balance	1,053,000		1,053,000		0
Total Loans [Abstract]
Recorded Balance	814,000		814,000		704,000
Unpaid Principal Balance	1,147,000		1,147,000		0
Average recorded investment and interest income recognized [Abstract]
Average investment in impaired loans	905,000	1,019,000	1,169,000	1,063,000
Interest income recognized	0	3,000	0	10,000
Loans Receivable, Modifications, Still Accruing Interest		304,000		304,000
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans	814,000		814,000		704,000
Troubled Debt Restructuring [Abstract]
Troubled Debt Restructurings Balance	386,000		386,000		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	4
Financing Receivables, Modifications during Period, Balance			54,000	185,000
Commercial and industrial loans | Pass
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	149,971,000		149,971,000		157,461,000
Commercial and industrial loans | Watch
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	951,000		951,000		1,588,000
Commercial and industrial loans | Substandard
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	8,806,000		8,806,000		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	48,000		48,000		119,000
60-89 days Past Due	21,000		21,000		24,000
90 Days or More Past Due	39,000		39,000		39,000
Total Past Due	108,000		108,000		182,000
Current	15,188,000		15,188,000		16,082,000
Total Loans Receivable	15,296,000		15,296,000		16,264,000
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	75,000		75,000		51,000
Unpaid Principal Balance	90,000		90,000		58,000
Total Loans [Abstract]
Recorded Balance	75,000		75,000		51,000
Unpaid Principal Balance	90,000		90,000		58,000
Average recorded investment and interest income recognized [Abstract]
Average investment in impaired loans	78,000	30,000	82,000	32,000
Interest income recognized	1,000	0	2,000	1,000
Loans Receivable, Modifications, Still Accruing Interest	29,000		29,000
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans	46,000		46,000		37,000
Troubled Debt Restructuring [Abstract]
Troubled Debt Restructurings Balance	29,000		29,000		14,000
Financing Receivable Modifications Performing Recorded Investment	29,000		29,000		14,000
Recorded Balance of Troubled Debt Restructurings [Abstract]
Financing Receivables, Modifications during Period, Number			3	1
Financing Receivables, Modifications during Period, Balance			16,000	14,000
Consumer loans | Pass
Loans Receivable Aging Analysis [Abstract]
Total Loans Receivable	15,245,000		15,245,000		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	51,000		51,000		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	11,204,000		11,204,000		8,193,000
Total Loans Receivable	11,204,000		11,204,000		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	11,204,000		11,204,000		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	569,000		569,000		2,205,000
60-89 days Past Due	626,000		626,000		1,004,000
90 Days or More Past Due	517,000		517,000		1,492,000
Total Past Due	1,712,000		1,712,000		4,701,000
Current	694,562,000		694,562,000		660,594,000
Total Loans Receivable	696,274,000		696,274,000		665,295,000
Total Loans 90 days & Accruing	0		0		0
Loans with a specific allowance [Abstract]
Recorded Balance	2,990,000		2,990,000		1,750,000
Unpaid Principal Balance	3,691,000		3,691,000		2,252,000
Specific Allowance	446,000		446,000		457,000
Loans without a specific allowance [Abstract]
Recorded Balance	2,923,000		2,923,000		4,158,000
Unpaid Principal Balance	3,535,000		3,535,000		5,168,000
Total Loans [Abstract]
Recorded Balance	5,913,000		5,913,000		5,908,000
Unpaid Principal Balance	7,226,000		7,226,000		7,420,000
Average recorded investment and interest income recognized [Abstract]
Average investment in impaired loans	5,937,000	6,220,000	6,170,000	6,236,000
Interest income recognized	2,000	7,000	4,000	21,000
Balances of Nonaccrual Loans [Abstract]
Recorded balance of nonaccrual loans	5,811,000		5,811,000		5,902,000
Troubled Debt Restructuring [Abstract]
Troubled Debt Restructurings Balance	2,852,000		2,852,000		2,917,000
Financing Receivable Modifications Performing Recorded Investment	102,000		102,000		6,000
Recorded Balance of Troubled Debt Restructurings [Abstract]
Financing Receivables, Modifications during Period, Number			5	7
Financing Receivables, Modifications during Period, Balance			$ 533,000	$ 1,936,000