Fair Value Measurements (Narrative) (Details) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2011
Fair Value Measurements [Abstract]
Conforming mortgage loans held for sale	$ 128,125,000
OREO and foreclosed property	126,657,000				125,046,000
Property write-downs included in earnings	2,556,000	906,000
Fair value Level 3 to Level 2 transfers amount	1,085,000
Number of FDIC-assisted transactions were excluded in assets and liabilities measured on a non-recurring basis			4	4
Impaired non-covered loans with an outstanding balance	5,104,000				4,532,000
Reserve in allowance for loan losses	$ 1,960,000				$ 2,186,000