Fair Market Value of Financial Assets and Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Other real estate owned [Abstract]
Maximum frequency of periodic reviews of real estate owned in general				24 months
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total recognized gains (losses) Included in net income	$ (351)		$ (39)	$ (381)	$ (546)
Total gain (losses) for the period included in net income attributable to the change in unrealized gains or losses related to assets still held at the reporting date	(351)		(39)	(381)	(546)
Total gains (losses), noninterest income	(351)		(39)	$ (381)	(546)
Minimum [Member]
Other real estate owned [Abstract]
Frequency of periodic reviews				12 months
Maximum [Member]
Other real estate owned [Abstract]
Frequency of periodic reviews				18 months
Recurring [Member] | Fair Value [Member]
Available-for-sale securities [Abstract]
U.S. Treasury and government agencies	202,050	$ 188,932		$ 202,050		$ 188,932
State and political subdivisions	135,459	137,458		135,459		137,458
U.S. government sponsored agency mortgage-backed securities	214,176	288,907		214,176		288,907
CRA investment funds	25,028	24,889		25,028		24,889
Mortgage servicing rights	3,030	2,968		3,030		2,968
Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Available-for-sale securities [Abstract]
U.S. Treasury and government agencies	19,997	492		19,997		492
State and political subdivisions	0	0		0		0
U.S. government sponsored agency mortgage-backed securities	0	0		0		0
CRA investment funds	25,028	24,889		25,028		24,889
Mortgage servicing rights	0	0		0		0
Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Available-for-sale securities [Abstract]
U.S. Treasury and government agencies	182,053	188,440		182,053		188,440
State and political subdivisions	135,459	137,458		135,459		137,458
U.S. government sponsored agency mortgage-backed securities	214,176	288,907		214,176		288,907
CRA investment funds	0	0		0		0
Mortgage servicing rights	0	0		0		0
Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Available-for-sale securities [Abstract]
U.S. Treasury and government agencies	0	0		0		0
State and political subdivisions	0	0		0		0
U.S. government sponsored agency mortgage-backed securities	0	0		0		0
CRA investment funds	0	0		0		0
Mortgage servicing rights	3,030	2,968		3,030		2,968
Recurring [Member] | Mortgage Servicing Rights [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	3,235	3,112	3,062	2,968	3,424	3,424
Total recognized gains (losses) Included in net income	(228)		80	(37)	(212)
Issues	146		89	443	234
Settlements	(123)		(119)	(344)	(334)
Ending balance	3,030	2,968	3,112	3,030	3,112	2,968
Total gain (losses) for the period included in net income attributable to the change in unrealized gains or losses related to assets still held at the reporting date	(228)		80	(37)	(212)
Total gains (losses), noninterest income	(228)		80	(37)	(212)
Nonrecurring [Member]
Impaired loan (collateral dependent) [Abstract]
Impaired loans, fair value adjustments	300	300	1,300	900	1,500	400
Other real estate owned [Abstract]
Other real estate /assets owned, fair value adjustment	800	300	$ 200	1,100	$ 1,400	1,700
Nonrecurring [Member] | Fair Value [Member]
Assets measured-nonrecurring basis [Abstract]
Impaired loans (collateral dependent)	2,195	4,665		2,195		4,665
Other real estate /assets owned	4,015	6,472		4,015		6,472
Nonrecurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets measured-nonrecurring basis [Abstract]
Impaired loans (collateral dependent)	0	0		0		0
Other real estate /assets owned	0	0		0		0
Nonrecurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets measured-nonrecurring basis [Abstract]
Impaired loans (collateral dependent)	0	0		0		0
Other real estate /assets owned	0	0		0		0
Nonrecurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Assets measured-nonrecurring basis [Abstract]
Impaired loans (collateral dependent)	2,195	4,665		2,195		4,665
Other real estate /assets owned	$ 4,015	$ 6,472		$ 4,015		$ 6,472