Business Combinations (Summary Of Acquisitions) (Details) (USD $) In Thousands	9 Months Ended
	Sep. 30, 2011
Lincoln Park [Member]
Date of acquisition	April 23, 2010
Fair value of assets acquired, at the acquisition date	$ 157,078
Fair value of loans acquired, at the acquisition date	103,420
Fair value of liabilities assumed, at the acquisition date	192,018
Wheatland [Member]
Date of acquisition	April 23, 2010
Fair value of assets acquired, at the acquisition date	343,870
Fair value of loans acquired, at the acquisition date	175,277
Fair value of liabilities assumed, at the acquisition date	415,560
Ravenswood [Member]
Date of acquisition	August 6, 2010
Fair value of assets acquired, at the acquisition date	173,919
Fair value of loans acquired, at the acquisition date	97,956
Fair value of liabilities assumed, at the acquisition date	122,943
Community First Bank - Chicago [Member]
Date of acquisition	February 4, 2011
Fair value of assets acquired, at the acquisition date	50,891
Fair value of loans acquired, at the acquisition date	27,332
Fair value of liabilities assumed, at the acquisition date	49,779
The Bank Of Commerce [Member]
Date of acquisition	March 25, 2011
Fair value of assets acquired, at the acquisition date	173,986
Fair value of loans acquired, at the acquisition date	77,887
Fair value of liabilities assumed, at the acquisition date	168,472
First Chicago [Member]
Date of acquisition	July 8, 2011
Fair value of assets acquired, at the acquisition date	768,873
Fair value of loans acquired, at the acquisition date	330,203
Fair value of liabilities assumed, at the acquisition date	$ 741,508