Loans And Allowance For Credit Losses (Summary Of ALLL And Outstanding Loan Balances According To The Company's Impairment Method) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2011		Jun. 30, 2011		Mar. 31, 2011		Dec. 31, 2010
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Individually evaluated for impairment	$ 71,159				$ 42,045
Allowance for loan losses: Collectively evaluated for impairment	895,606				1,001,894
Allowance for loan losses: Purchased loans with evidence of credit deterioration	4,951				6,019
Allowance for loan losses: Total	971,716		1,010,059		1,049,958		1,237,733		1,349,800		1,440,341
Outstanding loan balances: Individually evaluated for impairment	982,241				1,134,183
Outstanding loan balances: Collectively evaluated for impairment	35,794,313				35,900,262
Outstanding loan balances: Purchased loans with evidence of credit deterioration	96,796				110,207
Total loans	36,873,350				37,144,652
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Individually evaluated for impairment	34,434				11,456
Allowance for loan losses: Collectively evaluated for impairment	581,925				616,369
Allowance for loan losses: Purchased loans with evidence of credit deterioration	0				0
Allowance for loan losses: Total	616,359		631,169		627,825		667,646		694,090		761,107
Outstanding loan balances: Individually evaluated for impairment	368,751				349,662
Outstanding loan balances: Collectively evaluated for impairment	18,707,731				18,964,702
Outstanding loan balances: Purchased loans with evidence of credit deterioration	0				0
Total loans	19,076,482				19,314,364
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Individually evaluated for impairment	24,141				20,971
Allowance for loan losses: Collectively evaluated for impairment	207,908				254,575
Allowance for loan losses: Purchased loans with evidence of credit deterioration	0				0
Allowance for loan losses: Total	232,049		248,744		275,546		392,852		480,514		487,235
Outstanding loan balances: Individually evaluated for impairment	505,902				668,022
Outstanding loan balances: Collectively evaluated for impairment	9,604,443				9,480,321
Outstanding loan balances: Purchased loans with evidence of credit deterioration	0				0
Total loans	10,110,345				10,148,343
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Individually evaluated for impairment	12,042				8,995
Allowance for loan losses: Collectively evaluated for impairment	90,349				114,120
Allowance for loan losses: Purchased loans with evidence of credit deterioration	0				0
Allowance for loan losses: Total	102,391		109,101		123,115		149,773		148,110		154,326
Outstanding loan balances: Individually evaluated for impairment	105,769				113,798
Outstanding loan balances: Collectively evaluated for impairment	6,938,508				6,817,277
Outstanding loan balances: Purchased loans with evidence of credit deterioration	0				0
Total loans	7,044,277				6,931,075
FDIC- Supported [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Individually evaluated for impairment	542				623
Allowance for loan losses: Collectively evaluated for impairment	15,424				16,830
Allowance for loan losses: Purchased loans with evidence of credit deterioration	4,951				6,019
Allowance for loan losses: Total	20,917	[1]	21,045	[1]	23,472	[1]	27,462	[1]	27,086	[1]	37,673	[1]
Outstanding loan balances: Individually evaluated for impairment	1,819				2,701
Outstanding loan balances: Collectively evaluated for impairment	543,631				637,962
Outstanding loan balances: Purchased loans with evidence of credit deterioration	96,796				110,207
Total loans	$ 642,246				$ 750,870

[1] The Purchased Loans section following contains further discussion related to FDIC-supported loans.