Estimated Fair Values (Estimated Fair Values For Certain Financial Assets And Financial Liabilities) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011	Dec. 31, 2010
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	$ 533,599		$ 639,730
Overnight investments	859,324		443,180
Investment securities available for sale	5,387,703		5,226,228
Investment securities held to maturity	907		1,342
Loans held for sale	47,271		86,333
FDIC Indemnification Asset	93,397		270,192		617,377	671,023
Income earned not collected	48,390		47,666
Stock issued by:
Deposits	17,874,066		18,086,025
Short-term borrowings	511,418		568,505
Long-term obligations	510,769		444,921
Payable to FDIC for loss share agreements	109,378		101,641
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	533,599		639,730
Overnight investments	859,324		443,180
Investment securities available for sale	5,387,703		5,226,228
Investment securities held to maturity	907		1,342
Loans held for sale	47,271		86,333
Loans covered by loss share agreements, net of allowance for loan and lease losses	975,906		1,669,263
Loans and leases not covered by loss share agreements, net of allowance for loan and lease losses	11,924,424		11,397,069
FDIC Indemnification Asset	93,397	[1]	270,192	[1]
Income earned not collected	48,390		47,666
Stock issued by:
Preferred stock	33,564		40,768
Deposits	17,874,066		18,086,025
Short-term borrowings	511,418		568,505
Long-term obligations	510,769		444,921
Payable to FDIC for loss share agreements	109,378		101,641
Accrued interest payable	6,737		9,353
Derivative Liability, Fair Value, Gross Liability	7,220		10,398
Carrying Value | Investment In Federal Home Loan Bank Of Atlanta Stock
Stock issued by:
Stock issued by Federal Home Loan Bank	30,813		36,139
Carrying Value | Investment In Federal Home Loan Bank Of San Francisco Stock
Stock issued by:
Stock issued by Federal Home Loan Bank	5,756		10,107
Carrying Value | Investment In Federal Home Loan Bank Of Seattle Stock
Stock issued by:
Stock issued by Federal Home Loan Bank	4,250		4,410
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	533,599		639,730
Overnight investments	859,324		443,180
Investment securities available for sale	5,387,703		5,226,228
Investment securities held to maturity	974		1,448
Loans held for sale	47,956		87,654
Loans covered by loss share agreements, net of allowance for loan and lease losses	956,388		1,635,878
Loans and leases not covered by loss share agreements, net of allowance for loan and lease losses	11,589,149		11,238,597
FDIC Indemnification Asset	38,438	[1]	100,161	[1]
Income earned not collected	48,390		47,666
Stock issued by:
Preferred stock	34,786		40,793
Deposits	17,898,570		18,126,893
Short-term borrowings	511,418		568,505
Long-term obligations	526,037		472,642
Payable to FDIC for loss share agreements	111,941		111,679
Accrued interest payable	6,737		9,353
Derivative Liability, Fair Value, Gross Liability	7,220		10,398
Fair Value | Investment In Federal Home Loan Bank Of Atlanta Stock
Stock issued by:
Stock issued by Federal Home Loan Bank	30,813		36,139
Fair Value | Investment In Federal Home Loan Bank Of San Francisco Stock
Stock issued by:
Stock issued by Federal Home Loan Bank	5,756		10,107
Fair Value | Investment In Federal Home Loan Bank Of Seattle Stock
Stock issued by:
Stock issued by Federal Home Loan Bank	$ 4,250		$ 4,410

[1] The fair value of the FDIC receivable excludes receivable related to accretable yield to be amortized in prospective periods.