Disclosures about fair value of assets and liabilities (Details 5) (Level 3 [Member], USD $) In Thousands, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Impaired Loans [Member]
Qualitative information about unobservable inputs used in recurring and nonrecurring Level 3 fair value measurements, other than goodwill
Fair Value	$ 6,992	$ 8,652
Valuation Technique	Collateral based measurement	Collateral based measurement
Unobservable Inputs	Discount to reflect current market conditions and ultimate collectability	Discount to reflect current market conditions and ultimate collectability
Mortgage Servicing Rights [Member]
Qualitative information about unobservable inputs used in recurring and nonrecurring Level 3 fair value measurements, other than goodwill
Fair Value	$ 5,892	$ 5,145
Valuation Technique	Discounted cashflows	Discounted cashflows
Unobservable Inputs	Discount rate, Constant prepayment rate, Probably of default	Discount rate, Constant prepayment rate, Probably of default
Maximum [Member] | Impaired Loans [Member]
Qualitative information about unobservable inputs used in recurring and nonrecurring Level 3 fair value measurements, other than goodwill
Discount to reflect current market conditions and ultimate collectability	15.00%	15.00%
Maximum [Member] | Mortgage Servicing Rights [Member]
Qualitative information about unobservable inputs used in recurring and nonrecurring Level 3 fair value measurements, other than goodwill
Discount rate	15.00%	15.00%
Constant prepayment rate	7.00%	7.00%
Probably of default	10.00%	10.00%
Minimum [Member] | Impaired Loans [Member]
Qualitative information about unobservable inputs used in recurring and nonrecurring Level 3 fair value measurements, other than goodwill
Discount to reflect current market conditions and ultimate collectability	10.00%	10.00%
Minimum [Member] | Mortgage Servicing Rights [Member]
Qualitative information about unobservable inputs used in recurring and nonrecurring Level 3 fair value measurements, other than goodwill
Discount rate	10.00%	10.00%
Constant prepayment rate	4.00%	4.00%
Probably of default	1.00%	1.00%
Weighted Average [Member] | Impaired Loans [Member]
Qualitative information about unobservable inputs used in recurring and nonrecurring Level 3 fair value measurements, other than goodwill
Discount to reflect current market conditions and ultimate collectability	12.00%	12.00%
Weighted Average [Member] | Mortgage Servicing Rights [Member]
Qualitative information about unobservable inputs used in recurring and nonrecurring Level 3 fair value measurements, other than goodwill
Discount rate	12.00%	12.00%
Constant prepayment rate	4.60%	4.60%
Probably of default	4.50%	4.50%