Summary of Significant Accounting Policies Mortgage Servicing Rights Mortgage Banking Income (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Change in Accounting Estimate [Line Items]
Mortgage banking income	$ 25,674	$ 29,304	$ 25,061
Change in Accounting Method Accounted for as Change in Estimate [Member] | Interest Rate Lock Commitments [Member] | Mortgage Banking Income [Member]
Change in Accounting Estimate [Line Items]
Mortgage Banking Income, Fair Value Adjustments on Derivative Financial Instruments		3,300
Scenario, Previously Reported [Member]
Change in Accounting Estimate [Line Items]
Mortgage banking income		29,304	25,061
Scenario, Adjustment [Member]
Change in Accounting Estimate [Line Items]
Mortgage banking income		27,853	25,536
Difference [Member]
Change in Accounting Estimate [Line Items]
Mortgage banking income		$ 1,451	$ (475)