Fair Value Measurement (Schedule of a Description of the Valuation Technique, Unobservable Input, and Qualitative Information for the Company's Assets and Liabilities Classfied as Level 3) (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2012	Dec. 31, 2011
Constant prepayment rate	19.88%	20.39%
Discount rate	8.59%	8.60%
Weighted Average [Member]
Credit spread	5.7
Minimum [Member]
Credit spread	5.4
Maximum [Member]
Credit spread	6.7
Mortgage Servicing Rights [Member] | Level 3 [Member]
Fair value measurements, Valuation Techniques	Discounted cashflow
Junior Subordinated Debentures [Member] | Level 3 [Member]
Fair value measurements, Valuation Techniques	Discounted cashflow