Estimated Fair Values (Estimated Fair Values For Certain Financial Assets And Financial Liabilities) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013		Jun. 30, 2013	Dec. 31, 2012		Sep. 30, 2012	Jun. 30, 2012	Dec. 31, 2011
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	$ 569,118	[1]		$ 639,730	[2]
Overnight investments	1,354,131	[1]		443,180	[2]
Investment securities available for sale	5,161,585	[1]		5,226,228	[2]
Investment securities held to maturity	1,013	[1]		1,342	[2]
Loans held for sale	43,054	[1]		86,333	[2]
FDIC Indemnification Asset	100,553	[1]	158,013	270,192	[1]	329,619	405,626	617,377
Income earned not collected	46,110	[1]		47,666	[2]
Stock issued by:
Deposits	18,063,319	[1]		18,086,025	[2]
Payable to FDIC for loss share agreements	107,419			101,641
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	569,118			639,730
Overnight investments	1,354,131			443,180
Investment securities available for sale	5,161,585			5,226,228
Investment securities held to maturity	1,013			1,342
Loans held for sale	43,054			86,333
Loans covered by loss share agreements, net of allowance for loan and lease losses	1,128,764			1,669,263
Loans and leases not covered by loss share agreements, net of allowance for loan and lease losses	11,706,303			11,397,069
FDIC Indemnification Asset	100,553	[3]		270,192	[3]
Income earned not collected	46,110			47,666
Stock issued by:
Preferred stock	31,749			40,768
Deposits	18,063,319			18,086,025
Short-term borrowings	604,435			568,505
Long-term obligations	510,963			444,921
Payable to FDIC for loss share agreements	107,419			101,641
Accrued interest payable	6,051			9,353
Derivative Liability, Fair Value, Gross Liability	7,909			10,398
Carrying Value | Investment In Federal Home Loan Bank Of Atlanta Stock
Stock issued by:
Stock issued by Federal Home Loan Bank	31,938			36,139
Carrying Value | Investment In Federal Home Loan Bank Of San Francisco Stock
Stock issued by:
Stock issued by Federal Home Loan Bank	7,024			10,107
Carrying Value | Investment In Federal Home Loan Bank Of Seattle Stock
Stock issued by:
Stock issued by Federal Home Loan Bank	4,290			4,410
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	569,118			639,730
Overnight investments	1,354,131			443,180
Investment securities available for sale	5,161,585			5,226,228
Investment securities held to maturity	1,080			1,448
Loans held for sale	44,819			87,654
Loans covered by loss share agreements, net of allowance for loan and lease losses	1,106,189			1,635,878
Loans and leases not covered by loss share agreements, net of allowance for loan and lease losses	11,480,252			11,238,597
FDIC Indemnification Asset	28,450	[3]		100,161	[3]
Income earned not collected	46,110			47,666
Stock issued by:
Preferred stock	32,996			40,793
Deposits	18,089,336			18,126,893
Short-term borrowings	604,435			568,505
Long-term obligations	530,080			472,642
Payable to FDIC for loss share agreements	123,321			125,065
Accrued interest payable	6,051			9,353
Derivative Liability, Fair Value, Gross Liability	7,909			10,398
Fair Value | Investment In Federal Home Loan Bank Of Atlanta Stock
Stock issued by:
Stock issued by Federal Home Loan Bank	31,938			36,139
Fair Value | Investment In Federal Home Loan Bank Of San Francisco Stock
Stock issued by:
Stock issued by Federal Home Loan Bank	7,024			10,107
Fair Value | Investment In Federal Home Loan Bank Of Seattle Stock
Stock issued by:
Stock issued by Federal Home Loan Bank	$ 4,290			$ 4,410

[1] Unaudited

[2] Derived from 2012 Annual Report on Form 10-K.

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