Transfers of Financial Assets and Mortgage Servicing Assets Reserve for loan repurchases (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Reserve For Loan Respurchases [Roll Forward]
Beginning balance	$ 2,648	$ 2,394	$ 2,617	$ 2,269
Provision	447	522	1,462	1,103
Loss on repurchased loans and settlements	(586)	(312)	(1,570)	(768)
Ending balance	$ 2,509	$ 2,604	$ 2,509	$ 2,604