Business Combinations (Summary of Acquisitions) (Details) (USD $)	6 Months Ended						0 Months Ended
	Jun. 30, 2011	Jun. 30, 2011 Lincoln Park [Member]	Jun. 30, 2011 Wheatland [Member]	Jun. 30, 2011 Ravenswood [Member]	Jun. 30, 2011 Community First Bank - Chicago [Member]	Jun. 30, 2011 The Bank Of Commerce [Member]	Apr. 13, 2011 River City Mortgage, LLC [Member]	Feb. 03, 2011 Woodfield Planning Corporation [Member]
Date of acquisition		April 23, 2010	April 23, 2010	August 6, 2010	February 4, 2011	March 25, 2011
Fair value of assets acquired, at the acquisition date		$ 157,078,000	$ 343,870,000	$ 173,919,000	$ 50,891,000	$ 173,986,000
Fair value of loans acquired, at the acquisition date		103,420,000	175,277,000	97,956,000	27,332,000	77,887,000
Fair value of liabilities assumed, at the acquisition date		192,018,000	415,560,000	122,943,000	49,779,000	168,472,000
Additional goodwill recorded on acquisition	2,111,000
Mortgage loans acquired							$ 500,000,000	$ 180,000,000