Loans Details Narrative (Details) (USD $)	3 Months Ended							3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012	Dec. 31, 2010	Feb. 19, 2010 First Bank Branches [Member]	Feb. 19, 2010 George Washington Transaction [Member]	May 14, 2010 Midwest Transaction [Member]	Mar. 31, 2013 Covered Loans [Member]	Mar. 31, 2012 Covered Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Consumer Loans Guaranteed by Government	$ 3,500,000	$ 3,300,000	$ 3,400,000
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield, Reclassifications from Nonaccretable Difference	10,569,000	11,813,000
Acquired Non Impaired Loans	54,100,000	99,200,000	54,200,000	162,600,000
Covered Loans Loss Share Receivable	95,593,000	171,136,000	113,734,000
Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums	6,800,000	6,600,000	6,500,000
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Acquired During Period, Not Accounted for Using Income Recognition Model, at Acquisition					275,600,000	177,800,000	1,800,000,000
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Outstanding Balance	1,040,245,000	1,515,024,000	1,200,000,000
Provision for Loan Losses Before Benefit Attributable to FDIC Loss Share Agreements								9,677,000	10,831,000
Benefit Attributable to FDIC Loss Share Agreements								(5,539,000)	(4,899,000)
Provision for Loan Lease and Other Losses Covered	$ 4,138,000	$ 5,932,000						$ 4,138,000	$ 5,932,000
Loans Due Ninety Days or More or on Nonaccrual Status	0
Days past due for nonaccrual status credit card loans	120 days