Estimated Fair Values (Estimated Fair Values For Certain Financial Assets And Financial Liabilities) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014		Mar. 31, 2014	Dec. 31, 2013		Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	$ 566,952			$ 533,599
Overnight investments	1,118,474			859,324
Investment securities available for sale	5,538,166			5,387,703
Investment securities held to maturity	693			907
Loans held for sale	49,851			47,271
Loans and Leases Receivable, Net Amount	13,318,710			12,900,330
FDIC Indemnification Asset	49,959		74,784	93,397		158,013	195,942	270,192
Income earned not collected	49,019			48,390
Deposits	18,556,758			17,874,066
FDIC loss share payable	114,281			109,378
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	566,952			533,599
Overnight investments	1,118,474			859,324
Investment securities available for sale	5,538,166			5,387,703
Investment securities held to maturity	693			907
Loans held for sale	49,851			47,271
Loans and Leases Receivable, Net Amount	13,318,710			12,900,330
FDIC Indemnification Asset	49,959	[1]		93,397	[1]
Income earned not collected	49,019			48,390
Stock issued by Federal Home Loan Bank	32,878			40,819
Preferred stock	15,462			33,564
Deposits	18,556,758			17,874,066
Short-term borrowings	788,540			511,418
Long-term obligations	314,529			510,769
FDIC loss share payable	114,281			109,378
Accrued interest payable	7,297			6,737
Derivative Liability, Fair Value, Gross Liability	5,933			7,220
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	566,952			533,599
Overnight investments	1,118,474			859,324
Investment securities available for sale	5,538,166			5,387,703
Investment securities held to maturity	729			974
Loans held for sale	50,675			47,956
Loans and Leases Receivable, Net Amount	12,846,888			12,545,537
FDIC Indemnification Asset	22,741	[1]		38,438	[1]
Income earned not collected	49,019			48,390
Stock issued by Federal Home Loan Bank	32,878			40,819
Preferred stock	16,199			34,786
Deposits	18,113,243			17,898,570
Short-term borrowings	788,540			511,418
Long-term obligations	324,874			526,037
FDIC loss share payable	119,465			111,941
Accrued interest payable	7,297			6,737
Derivative Liability, Fair Value, Gross Liability	$ 5,933			$ 7,220

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