Business Combinations (Summary of Acquisition of Certain Assets and the Assumption of Liabilities, of Six Financial Institutions in FDIC-Assisted Transactions) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended			0 Months Ended									0 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Apr. 23, 2010 Lincoln Park [Member]		Apr. 23, 2010 Wheatland [Member]		Aug. 06, 2010 Ravenswood [Member]		Feb. 03, 2011 Community First Bank - Chicago [Member]	Feb. 04, 2011 Community First Bank - Chicago [Member]		Mar. 25, 2011 The Bank Of Commerce [Member]		Jul. 08, 2011 First Chicago [Member]		Feb. 10, 2012 Charter National [Member]		Jul. 20, 2012 Second Federal [Member]		Sep. 28, 2012 First United Bank [Member]
Date of acquisition				Apr. 23, 2010		Apr. 23, 2010		Aug. 06, 2010		Feb. 04, 2011			Mar. 25, 2011		Jul. 08, 2011		Feb. 10, 2012		Jul. 20, 2012		Sep. 28, 2012
Fair value of assets acquired, at the acquisition date	$ 1,158,925	$ 1,257,085	$ 673,277	$ 157,078		$ 343,870		$ 173,919		$ 50,891			$ 173,986		$ 768,873		$ 92,409		$ 171,625		$ 328,408
Fair value of loans acquired, at the acquisition date				103,420		175,277		97,956			27,332		77,887		330,203		45,555		0		77,964
Fair value of liabilities assumed, at the acquisition date				192,018		415,560		122,943		49,779			168,472		741,508		91,570		171,582		321,734
FDIC Indemnification Asset	208,160	344,251	118,182	23,289	[1]	90,478	[1]	43,996	[1]		6,672	[1]	48,853	[1]	273,312	[1]	13,164	[1]	0	[1]	67,190	[1]
Gain on bargain purchase recognized	$ 7,503	$ 37,974	$ 44,231	$ 4,179		$ 22,315		$ 6,842		$ 1,957			$ 8,627		$ 27,390		$ 785		$ 43		$ 6,675

[1] As no assets subject to loss sharing agreements were acquired in the acquisition of Second Federal, there was no fair value of reimbursable losses.