Mortgage Servicing Rights (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Mortgage Servicing Rights
Carrying amount before valuation allowance at beginning of year	$ 15,401	$ 16,321	$ 16,670
Additions - servicing obligations that result from transfers of financial assets	3,651	2,330	3,101
Amortization	(3,909)	(3,250)	(3,450)
Carrying amount before valuation allowance at end of year	15,143	15,401	16,321
Valuation allowance at beginning of year	(7,265)	(7,117)	(7,820)
(Provision for) recovery of valuation allowance	(931)	(148)	703
Valuation allowance at end of year	(8,196)	(7,265)	(7,117)
Net carrying amount at end of year	$ 6,947	$ 8,136	$ 9,204