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	Sep. 30, 2012		Jun. 30, 2012		Dec. 31, 2011		Sep. 30, 2011		Jun. 30, 2011		Dec. 31, 2010
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Individually evaluated for impairment	$ 81,893				$ 42,045
Allowance for loan losses: Collectively evaluated for impairment	840,667				1,001,894
Allowance for loan losses: Purchased loans with evidence of credit deterioration	2,781				6,019
Allowance for loan losses: Total	925,341		971,716		1,049,958		1,148,903		1,237,733		1,440,341
Outstanding loan balances: Individually evaluated for impairment	939,150				1,134,183
Outstanding loan balances: Collectively evaluated for impairment	36,139,197				35,900,262
Outstanding loan balances: Purchased loans with evidence of credit deterioration	92,472				110,207
Total loans	37,170,819				37,144,652
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Individually evaluated for impairment	36,278				11,456
Allowance for loan losses: Collectively evaluated for impairment	568,513				616,369
Allowance for loan losses: Purchased loans with evidence of credit deterioration	0				0
Allowance for loan losses: Total	604,791		616,359		627,825		661,151		667,646		761,107
Outstanding loan balances: Individually evaluated for impairment	344,411				349,662
Outstanding loan balances: Collectively evaluated for impairment	18,947,322				18,964,702
Outstanding loan balances: Purchased loans with evidence of credit deterioration	0				0
Total loans	19,291,733				19,314,364
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Individually evaluated for impairment	30,579				20,971
Allowance for loan losses: Collectively evaluated for impairment	179,508				254,575
Allowance for loan losses: Purchased loans with evidence of credit deterioration	0				0
Allowance for loan losses: Total	210,087		232,049		275,546		311,709		392,852		487,235
Outstanding loan balances: Individually evaluated for impairment	495,569				668,022
Outstanding loan balances: Collectively evaluated for impairment	9,600,163				9,480,321
Outstanding loan balances: Purchased loans with evidence of credit deterioration	0				0
Total loans	10,095,732				10,148,343
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Individually evaluated for impairment	15,036				8,995
Allowance for loan losses: Collectively evaluated for impairment	82,577				114,120
Allowance for loan losses: Purchased loans with evidence of credit deterioration	0				0
Allowance for loan losses: Total	97,613		102,391		123,115		150,101		149,773		154,326
Outstanding loan balances: Individually evaluated for impairment	97,589				113,798
Outstanding loan balances: Collectively evaluated for impairment	7,097,199				6,817,277
Outstanding loan balances: Purchased loans with evidence of credit deterioration	0				0
Total loans	7,194,788				6,931,075
FDIC- Supported [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Individually evaluated for impairment	0				623
Allowance for loan losses: Collectively evaluated for impairment	10,069				16,830
Allowance for loan losses: Purchased loans with evidence of credit deterioration	2,781				6,019
Allowance for loan losses: Total	12,850	[1]	20,917	[1]	23,472	[1]	25,942	[1]	27,462	[1]	37,673	[1]
Outstanding loan balances: Individually evaluated for impairment	1,581				2,701
Outstanding loan balances: Collectively evaluated for impairment	494,513				637,962
Outstanding loan balances: Purchased loans with evidence of credit deterioration	92,472				110,207
Total loans	$ 588,566				$ 750,870

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