Allowance for Loan Losses, Loans by Class Modified as Troubled Debt Restructured Loans (Details) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Financing Receivable, Modifications [Line Items]
Specific reserves	$ 187,000	$ 904,000	$ 187,000	$ 904,000	$ 759,000
Troubled debt restructured loans, performing	2,100,000		2,100,000		4,900,000
Commitments to lend additional amounts to customers with outstanding loans that are classified as troubled debt restructurings	0	0	0	0	0
Modifications involving a reduction of the stated interest rate of the loan period			5 years
Loans by class modified as troubled debt restructured loans [Abstract]
Number of Loans	4	4	16	12	19
Pre Modification Outstanding Recorded Investment	406,000	897,000	1,489,000	4,230,000	4,846,000
Post-Modification Recorded Outstanding Investment	391,000	847,000	1,425,000	4,176,000	4,772,000
Increase in allowance for loan losses	0	0	19,000	126,000
General loss reserve					680,000
TDR's charge-offs	15,000	50,000	64,000	54,000	74,000
Period after which loan is considered to be in payment default			90 days
Troubled debt restructurings that subsequently default [Abstract]
Number of Loans					1
Recorded Investment					12,000
Number of Loans		0		1
Recorded Investment		0		12,000
Charge offs on troubled debt restructurings that subsequently defaulted		0		12,000	12,000
Minimum [Member]
Financing Receivable, Modifications [Line Items]
Modifications involving a reduction of the stated interest rate of the loan period				2 years	2 years
Period of modifications involving extension of maturity date			6 months	3 years	3 years
Maximum [Member]
Financing Receivable, Modifications [Line Items]
Modifications involving a reduction of the stated interest rate of the loan period				8 years	8 years
Period of modifications involving extension of maturity date			15 years	10 years	10 years
Performing [Member]
Financing Receivable, Modifications [Line Items]
Troubled debt restructured loans, performing	1,600,000		1,600,000		4,700,000
Commercial Real Estate [Member]
Loans by class modified as troubled debt restructured loans [Abstract]
Number of Loans		0	1	2	3
Pre Modification Outstanding Recorded Investment		0	116,000	3,032,000	3,224,000
Post-Modification Recorded Outstanding Investment		0	116,000	3,032,000	3,224,000
Troubled debt restructurings that subsequently default [Abstract]
Number of Loans					0
Recorded Investment					0
Number of Loans		0		0
Recorded Investment		0		0
Residential 1st Mortgages [Member]
Loans by class modified as troubled debt restructured loans [Abstract]
Number of Loans	1	4	5	4	5
Pre Modification Outstanding Recorded Investment	185,000	897,000	331,000	897,000	995,000
Post-Modification Recorded Outstanding Investment	173,000	847,000	312,000	847,000	940,000
Troubled debt restructurings that subsequently default [Abstract]
Number of Loans					0
Recorded Investment					0
Number of Loans		0		0
Recorded Investment		0		0
Home Equity Lines and Loans [Member]
Loans by class modified as troubled debt restructured loans [Abstract]
Number of Loans	1	0	4	2	7
Pre Modification Outstanding Recorded Investment	46,000	0	414,000	55,000	381,000
Post-Modification Recorded Outstanding Investment	43,000	0	369,000	51,000	362,000
Troubled debt restructurings that subsequently default [Abstract]
Number of Loans					1
Recorded Investment					12,000
Number of Loans		0		1
Recorded Investment		0		12,000
Agricultural [Member]
Loans by class modified as troubled debt restructured loans [Abstract]
Number of Loans	2	0	3	1	1
Pre Modification Outstanding Recorded Investment	175,000	0	355,000	140,000	140,000
Post-Modification Recorded Outstanding Investment	175,000	0	355,000	140,000	140,000
Troubled debt restructurings that subsequently default [Abstract]
Number of Loans					0
Recorded Investment					0
Number of Loans		0		0
Recorded Investment		0		0
Commercial [Member]
Loans by class modified as troubled debt restructured loans [Abstract]
Number of Loans	0	0	3	2	2
Pre Modification Outstanding Recorded Investment	0	0	273,000	82,000	82,000
Post-Modification Recorded Outstanding Investment	0	0	273,000	82,000	82,000
Troubled debt restructurings that subsequently default [Abstract]
Number of Loans					0
Recorded Investment					0
Number of Loans		0		0
Recorded Investment		0		0
Agricultural Real Estate [Member]
Loans by class modified as troubled debt restructured loans [Abstract]
Number of Loans		0		0
Pre Modification Outstanding Recorded Investment		0		0
Post-Modification Recorded Outstanding Investment		0		0
Troubled debt restructurings that subsequently default [Abstract]
Number of Loans					0
Recorded Investment					0
Number of Loans		0		0
Recorded Investment		0		0
Real Estate Construction [Member]
Loans by class modified as troubled debt restructured loans [Abstract]
Number of Loans		0		0
Pre Modification Outstanding Recorded Investment		0		0
Post-Modification Recorded Outstanding Investment		0		0
Troubled debt restructurings that subsequently default [Abstract]
Number of Loans					0
Recorded Investment					0
Number of Loans		0		0
Recorded Investment		0		0
Consumer & Other [Member]
Loans by class modified as troubled debt restructured loans [Abstract]
Number of Loans		0		1	1
Pre Modification Outstanding Recorded Investment		0		24,000	24,000
Post-Modification Recorded Outstanding Investment		0		24,000	24,000
Troubled debt restructurings that subsequently default [Abstract]
Number of Loans					0
Recorded Investment					0
Number of Loans		0		0
Recorded Investment		$ 0		$ 0