Estimated Fair Values (Estimated Fair Values For Certain Financial Assets And Financial Liabilities) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	$ 543,471		$ 533,599
Overnight investments	1,161,469		859,324
Investment securities available for sale	5,676,237		5,387,703
Investment securities held to maturity	782		907
Loans held for sale	53,361		47,271
FDIC Indemnification Asset	74,784		93,397
Income earned not collected	49,668		48,390
Deposits	18,763,545		17,874,066
FDIC loss share payable	111,339		109,378
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	543,471		533,599
Overnight investments	1,161,469		859,324
Investment securities available for sale	5,676,237		5,387,703
Investment securities held to maturity	782		907
Loans held for sale	53,361		47,271
Loans covered by loss share agreements, net of allowance for loan and lease losses	1,225,825		975,906
Loans and leases not covered by loss share agreements, net of allowance for loan and lease losses	12,022,277		11,924,424
FDIC Indemnification Asset	74,784	[1]	93,397	[1]
Income earned not collected	49,668		48,390
Preferred stock	17,783		33,564
Deposits	18,763,545		17,874,066
Short-term borrowings	617,794		511,418
Long-term obligations	440,300		510,769
FDIC loss share payable	111,339		109,378
Accrued interest payable	5,675		6,737
Derivative Liability, Fair Value, Gross Liability	6,501		7,220
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	543,471		533,599
Overnight investments	1,161,469		859,324
Investment securities available for sale	5,676,237		5,387,703
Investment securities held to maturity	835		974
Loans held for sale	54,057		47,956
Loans covered by loss share agreements, net of allowance for loan and lease losses	1,201,309		956,388
Loans and leases not covered by loss share agreements, net of allowance for loan and lease losses	11,659,364		11,589,149
FDIC Indemnification Asset	37,303	[1]	38,438	[1]
Income earned not collected	49,668		48,390
Stock issued by Federal Home Loan Bank	34,417		40,819
Preferred stock	18,521		34,786
Deposits	18,785,474		17,898,570
Short-term borrowings	617,794		511,418
Long-term obligations	453,313		526,037
FDIC loss share payable	115,129		111,941
Accrued interest payable	5,675		6,737
Derivative Liability, Fair Value, Gross Liability	$ 6,501		$ 7,220

[1] The fair value of the FDIC receivable excludes amortization expected to be recognized in prospective periods.