Fair Value Measurement (Narrative) (Details Textual) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012	Dec. 31, 2011	Jul. 15, 2020 Midwest [Member]	Mar. 31, 2013 Midwest [Member]	Dec. 31, 2012 Midwest [Member]	Mar. 31, 2012 Midwest [Member]	Apr. 14, 2020 George Washington [Member]	Mar. 31, 2013 George Washington [Member]	Dec. 31, 2012 George Washington [Member]	Mar. 31, 2012 George Washington [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Mortgage Servicing Rights	$ 21,378,000	$ 20,946,000	$ 21,316,000	$ 21,179,000
Mortgage Servicing rights Valuation Allowance	1,234,000	2,193,000	2,564,000	3,539,000
Mortgage Servicing Rights Net Carrying balance	20,144,000	18,753,000
Mortgage Servicing Rights (MSR) Impairment (Recovery)	1,330,000	1,346,000	975,000
Impaired Collateral Dependant Loans, Recorded Investment	58,900,000	65,200,000	57,800,000
Determination Of Specific Allowance For Loan Losses	4,500,000	5,200,000	3,300,000
Collateral Dependant Impaired and Non Accrual Loans Carrying Amount	54,400,000	60,000,000	54,500,000
Impairment of Real Estate	200,000	900,000	2,200,000
Impairment of Covered Other Real Esate Owned	100,000	600,000	1,700,000
Percent of available for sale securities classified as level 2	98.00%
Percent of available for sale securites at level 3	2.00%
True-up Liabitlity Discount Rate	2.91%	3.56%
True-up Liability Effect of Change in Discount Rate Increase By One Percent	900,000
Percent of FDIC Intrinsic Loss Estimate					20.00%
Intrinsic Loss Estimate of the FDIC					152,000,000
Percent of Asset Premium Paid					25.00%
Asset Premium Paid					20,000,000
Percent of cumulative shared loss payments under loss sharing agreements					25.00%				25.00%
Estimated fair value of true up liability						8,400,000	7,600,000	7,400,000		4,400,000	4,600,000	4,300,000
Percent of excess threshold paid by the Bank under loss sharing agreements									50.00%
Percent Theshold of Loss Sharing Agreements Paid by Bank									20.00%
Stated Threshold of Loss Sharing Agreements Paid by Bank									172,000,000
Percent of Asset Discount Under Loss Sharing Percent of Asset Discount Under Loss Sharing Agreements									25.00%
Asset discount received									$ 47,000,000
Number of loans that were 90 days or more past due, or were any on nonaccrual status	0