Disclosures about fair value of assets and liabilities (Details 4) (Fair Value, Measurements, Nonrecurring [Member], USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Other assets measured at fair value on a nonrecurring basis
Impaired loans	$ 6,992	$ 8,652
Mortgage servicing rights	5,892	5,145
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Other assets measured at fair value on a nonrecurring basis
Impaired loans
Mortgage servicing rights
Significant Other Observable Inputs (Level 2) [Member]
Other assets measured at fair value on a nonrecurring basis
Impaired loans
Mortgage servicing rights
Significant Unobservable Inputs (Level 3) [Member]
Other assets measured at fair value on a nonrecurring basis
Impaired loans	6,992	8,652
Mortgage servicing rights	$ 5,892	$ 5,145