Business Combinations (Narrative) (Details) (USD $)	3 Months Ended			6 Months Ended		12 Months Ended	6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended		6 Months Ended	12 Months Ended	3 Months Ended	6 Months Ended	3 Months Ended	6 Months Ended	0 Months Ended
	Jun. 30, 2011	Mar. 31, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010	Jun. 30, 2011 Lincoln Park [Member]	Dec. 31, 2010 Lincoln Park [Member]	Jun. 30, 2011 Wheatland [Member]	Dec. 31, 2010 Wheatland [Member]	Dec. 31, 2010 Lincoln Park And Wheatland [Member]	Jun. 30, 2011 Ravenswood [Member]	Dec. 31, 2010 Ravenswood [Member]	Mar. 31, 2011 Community First Bank - Chicago [Member]	Jun. 30, 2011 Community First Bank - Chicago [Member]	Mar. 31, 2011 The Bank Of Commerce [Member]	Jun. 30, 2011 The Bank Of Commerce [Member]	Oct. 22, 2010 Other Bank Acquisitions [Member]	Apr. 13, 2011 River City Mortgage, LLC [Member]
FDIC loss sharing percentage on purchased loans, OREO, and certain other assets				80.00%
Fair value of the reimbursable losses											$ 113,800,000
Fair value of the reimbursable losses	110,049,000		114,102,000	110,049,000	114,102,000	118,182,000							44,000,000		6,700,000		48,900,000
Bargain purchase gains	746,000	10,600,000	26,494,000	10,584,000	37,388,000	33,100,000		4,200,000		22,300,000			6,600,000	2,000,000		8,600,000
Fair value of assets acquired, at the acquisition date							157,078,000		343,870,000			173,919,000			50,891,000		173,986,000	22,900,000
Fair value of loans acquired, at the acquisition date							103,420,000		175,277,000			97,956,000			27,332,000		77,887,000	10,700,000
Fair value of liabilities assumed, at the acquisition date							192,018,000		415,560,000			122,943,000			49,779,000		168,472,000	22,900,000
Deposits																		22,800,000
Mortgage loans acquired																			500,000,000
Goodwill, Acquired During Period				$ 2,111,000														$ 1,700,000