Mortgage Servicing Rights (Details 2) (Mortgage Servicing Rights, USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Mortgage Servicing Rights
Change in Carrying Value of Mortgage Servicing Rights Accounted for Under the Amortization Method, Net of a Valuation Allowance
Balance at the beginning of the Period	$ 17,795	$ 16,220	$ 17,148	$ 15,153
Servicing Rights that Resulted From Asset Transfers	1,747	976	3,716	2,938
Amortization	(678)	(639)	(2,000)	(1,534)
Balance at the end of the Period	18,864	16,557	18,864	16,557
Fair Value of Mortgage Servicing Rights Accounted for Under the Amortization Method
Balance at the beginning of the Period	18,937	21,483	17,159	20,340
Balance at the end of the Period	$ 20,241	$ 17,156	$ 20,241	$ 17,156