Mortgage Servicing Rights (Details 2) (Mortgage Servicing Rights., USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
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	$ 15,153	$ 10,638	$ 1,796
Servicing Rights that Resulted From Asset Transfers	4,139	6,086	9,628
Amortization	(2,144)	(1,571)	(786)
Balance at the end of the Period	17,148	15,153	10,638
Valuation Allowance:
Balance at the beginning of the Period			292
Recoveries			(292)
Mortgage Servicing Rights Accounted for Under the Amortization Method, Net of a Valuation Allowance	17,148	15,153	10,638
Fair Value of Mortgage Servicing Rights Accounted for Under the Amortization Method
Balance at the beginning of the Period	20,340	14,853	1,504
Balance at the end of the Period	$ 17,159	$ 20,340	$ 14,853