Fair Value Measurement (Details) (Fair value measurement on a recurring basis [Member], USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Recorded amount of assets and liabilities measured at fair value on a recurring basis
Total assets measured at fair value	$ 149,438	$ 167,579
Obligations of U.S. government corporations and agencies [Member]
Recorded amount of assets and liabilities measured at fair value on a recurring basis
Total assets measured at fair value	133,964	151,701
Obligations of states and political subdivisions [Member]
Recorded amount of assets and liabilities measured at fair value on a recurring basis
Total assets measured at fair value	8,578	9,421
Corporate debt securities [Member]
Recorded amount of assets and liabilities measured at fair value on a recurring basis
Total assets measured at fair value	1,912	1,905
Mortgage servicing rights [Member]
Recorded amount of assets and liabilities measured at fair value on a recurring basis
Total assets measured at fair value	4,984	4,552
Level 1 [Member]
Recorded amount of assets and liabilities measured at fair value on a recurring basis
Total assets measured at fair value
Level 1 [Member] | Obligations of U.S. government corporations and agencies [Member]
Recorded amount of assets and liabilities measured at fair value on a recurring basis
Total assets measured at fair value
Level 1 [Member] | Obligations of states and political subdivisions [Member]
Recorded amount of assets and liabilities measured at fair value on a recurring basis
Total assets measured at fair value
Level 1 [Member] | Corporate debt securities [Member]
Recorded amount of assets and liabilities measured at fair value on a recurring basis
Total assets measured at fair value
Level 1 [Member] | Mortgage servicing rights [Member]
Recorded amount of assets and liabilities measured at fair value on a recurring basis
Total assets measured at fair value
Level 2 [Member]
Recorded amount of assets and liabilities measured at fair value on a recurring basis
Total assets measured at fair value	144,454	163,027
Level 2 [Member] | Obligations of U.S. government corporations and agencies [Member]
Recorded amount of assets and liabilities measured at fair value on a recurring basis
Total assets measured at fair value	133,964	151,701
Level 2 [Member] | Obligations of states and political subdivisions [Member]
Recorded amount of assets and liabilities measured at fair value on a recurring basis
Total assets measured at fair value	8,578	9,421
Level 2 [Member] | Corporate debt securities [Member]
Recorded amount of assets and liabilities measured at fair value on a recurring basis
Total assets measured at fair value	1,912	1,905
Level 3 [Member]
Recorded amount of assets and liabilities measured at fair value on a recurring basis
Total assets measured at fair value	4,984	4,552
Level 3 [Member] | Mortgage servicing rights [Member]
Recorded amount of assets and liabilities measured at fair value on a recurring basis
Total assets measured at fair value	$ 4,984	$ 4,552