Fair Value Measurements (Details 5) (Non-recurring, USD $)	3 Months Ended
	Mar. 31, 2014 Impaired loans	Mar. 31, 2014 Partnership investments	Mar. 31, 2014 Mortgage servicing rights	Mar. 31, 2014 Repossessions	Mar. 31, 2014 Other real estate	Mar. 31, 2014 Level 3	Dec. 31, 2013 Level 3	Mar. 31, 2014 Level 3 Partnership investments	Dec. 31, 2013 Level 3 Partnership investments	Mar. 31, 2014 Level 3 Mortgage servicing rights	Dec. 31, 2013 Level 3 Mortgage servicing rights	Mar. 31, 2014 Level 3 Repossessions	Dec. 31, 2013 Level 3 Repossessions	Mar. 31, 2014 Level 3 Other real estate	Dec. 31, 2013 Level 3 Other real estate	Mar. 31, 2014 Total	Dec. 31, 2013 Total	Mar. 31, 2014 Total Partnership investments	Dec. 31, 2013 Total Partnership investments	Mar. 31, 2014 Total Mortgage servicing rights	Dec. 31, 2013 Total Mortgage servicing rights	Mar. 31, 2014 Total Repossessions	Dec. 31, 2013 Total Repossessions	Mar. 31, 2014 Total Other real estate	Dec. 31, 2013 Total Other real estate
Fair value measurements
Impairment charges (recoveries)	$ 0	$ 30,000	$ 0	$ 0	$ (90,000)
Impaired loans - collateral based						996,000	670,000									996,000	670,000
Accrued income and other assets								2,002,000	2,156,000	4,759,000	4,844,000	7,998,000	4,262,000	2,892,000	5,490,000			2,002,000	2,156,000	4,759,000	4,844,000	7,998,000	4,262,000	2,892,000	5,490,000
Assets measured at fair value						$ 18,647,000	$ 17,422,000									$ 18,647,000	$ 17,422,000