Business Combinations (Summary Of Acquisition Of Certain Assets And The Assumption Of Liabilities, Of Seven Financial Institutions In FDIC-Assisted Transactions) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012
Lincoln Park [Member]
Business Acquisition [Line Items]
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]
Business Acquisition [Line Items]
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]
Business Acquisition [Line Items]
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]
Business Acquisition [Line Items]
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]
Business Acquisition [Line Items]
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]
Business Acquisition [Line Items]
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
Charter National [Member]
Business Acquisition [Line Items]
Date of acquisition	February 10, 2012
Fair value of assets acquired, at the acquisition date	92,409
Fair value of loans acquired, at the acquisition date	45,555
Fair value of liabilities assumed, at the acquisition date	$ 91,570