Loans (Details) (USD $)	6 Months Ended									3 Months Ended		6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011		Dec. 31, 2011		Jun. 30, 2012 Acquired Loans Noncovered [Member]	Dec. 31, 2011 Acquired Loans Noncovered [Member]	Jun. 30, 2011 Acquired Loans Noncovered [Member]	Jun. 30, 2012 Loss Share Receivable [Member]	Jun. 30, 2011 Loss Share Receivable [Member]	Jun. 30, 2012 Loss Share Receivable [Member]	Jun. 30, 2011 Loss Share Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Proceeds from Sale of Mortgage Loans Held-for-sale	410.2		211.6
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing							$ 0	$ 3,000	$ 2,917,000
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing Guaranteed By US Government	3,500,000		2,500,000		3,000,000
Loans and Leases Receivable, Gross, Commercial	5,404,971,000		4,808,305,000		5,107,747,000
Loans and Leases Receivable, Gross, Consumer, Mortgage	438,147,000		400,661,000		413,664,000
Loans and Leases Receivable, Gross, Consumer, Installment, Other	1,262,877,000		1,259,072,000		1,263,665,000
Loans and Leases Receivable, Gross, Consumer, Home Equity	766,840,000		738,719,000		743,982,000
Loans and Leases Receivable, Gross, Consumer, Revolving, Credit Card	142,586,000		143,828,000		146,356,000
Loans and Leases Receivable, Gross, Consumer, Lease Financing	84,507,000		57,634,000		73,530,000
Total noncovered loans	8,099,928,000	[1]	7,408,219,000	[1]	7,748,944,000	[1]	67,900,000	113,200,000	192,200,000
Loans and Leases Receivable, Allowance	103,849,000		109,187,000		107,699,000
Net noncovered loans	7,996,079,000		7,299,032,000		7,641,245,000
Covered Loans and Leases Receivable Gross	1,271,888,000	[2]	1,755,107,000	[2]						152,615,000	239,424,000	152,615,000	239,424,000
Covered Certain Loans Acquired in Transfer not Accounted for as Debt Securities Allowance for Loan Losses	42,606,000		33,360,000		36,417,000
Covered Loans and Leases Receivable Net	1,229,282,000		1,721,747,000		1,460,723,000
Net loans	9,225,361,000		9,020,779,000		9,101,968,000
Changes in Loss Share Receivable Associated with Covered Loans [Roll Forward]
Balance at beginning of period	1,497,140,000	[2]								171,136,000	265,981,000	205,664,000	288,605,000
Accretion										(8,877,000)	(9,868,000)	(18,534,000)	(21,498,000)
Increase due to impairment										6,218,000	7,675,000	11,117,000	22,854,000
FDIC reimbursement										(10,651,000)	(22,771,000)	(38,081,000)	(48,402,000)
Covered loans paid in full										(5,211,000)	(1,593,000)	(7,551,000)	(2,135,000)
Balance at end of the period	$ 1,271,888,000	[2]	$ 1,755,107,000	[2]						$ 152,615,000	$ 239,424,000	$ 152,615,000	$ 239,424,000

[1] (a)Includes acquired, noncovered loans of $67.9 million, $113.2 million and $192.2 million as of June 30, 2012,December 31, 2011 and June 30, 2011, respectively.

[2] Includes loss share receivable of $152.6 million, $205.7 million and $239.4 million as of June 30, 2012, December 31, 2011 and June 30, 2011, respectively.