Commitments, guarantees and contingencies (Summary of the Bank's Off-balance Sheet Financial Instruments) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Fair Value Disclosure, Off-balance Sheet Risks, Amount, Liability	$ 272,388	$ 251,599
Commitments To Extend Credit
Fair Value Disclosure, Off-balance Sheet Risks, Amount, Liability	245,906	224,531
Commitments Under Credit Card Lines Of Credit
Fair Value Disclosure, Off-balance Sheet Risks, Amount, Liability	24,321	22,847
Standby Letters Of Credit
Fair Value Disclosure, Off-balance Sheet Risks, Amount, Liability	$ 2,161	$ 4,221