Loans And Allowance For Credit Losses (Summary Of ALLL And Outstanding Loan Balances According To The Company's Impairment Method) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2013
Financing Receivable, Allowance for Credit Losses [Line Items]
Impaired Financing Receivable, Average Recorded Investment	$ 602,925	$ 829,533	$ 573,862	$ 853,216
Impaired Financing Receivable, Interest Income, Accrual Method	9,279	14,387	35,198	58,263
Allowance for loan losses: Individually evaluated for impairment	(46,103)		(46,103)			$ (41,713)
Allowance for loan losses: Collectively evaluated for impairment	549,132		549,132			560,150
Allowance for loan losses: Purchased loans with evidence of credit deterioration	1,205		1,205			2,800
Allowance for loan losses: Total	596,440	610,277	596,440	610,277	$ 609,375	604,663	$ 675,907	$ 746,291
Outstanding loan balances: Individually evaluated for impairment	494,603		494,603			521,909
Outstanding loan balances: Collectively evaluated for impairment	39,485,299		39,485,299			39,362,450
Financing Receivable Allowance For Credit Losses and Receivables Acquired With Deteriorated Credit Quality	133,221		133,221			179,299
Total loans	40,113,123		40,113,123			40,063,658
Commercial and Industrial Sector [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Impaired Financing Receivable, Average Recorded Investment	191,642	186,026	158,825	180,130
Impaired Financing Receivable, Interest Income, Accrual Method	1,314	2,335	5,525	8,819
Owner Occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Impaired Financing Receivable, Average Recorded Investment	138,194	232,484	135,212	235,380
Impaired Financing Receivable, Interest Income, Accrual Method	2,752	4,514	9,706	13,774
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Individually evaluated for impairment	(32,191)		(32,191)			(28,627)
Allowance for loan losses: Collectively evaluated for impairment	394,836		394,836			382,552
Allowance for loan losses: Purchased loans with evidence of credit deterioration	670		670			1,335
Allowance for loan losses: Total	427,697	412,045	427,697	412,045	437,770	412,514	442,965	469,213
Outstanding loan balances: Individually evaluated for impairment	279,928		279,928			259,207
Outstanding loan balances: Collectively evaluated for impairment	20,859,442		20,859,442			21,105,217
Financing Receivable Allowance For Credit Losses and Receivables Acquired With Deteriorated Credit Quality	64,280		64,280			79,940
Total loans	21,203,650		21,203,650			21,444,364
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Impaired Financing Receivable, Average Recorded Investment	31,506	59,735	31,920	62,404
Impaired Financing Receivable, Interest Income, Accrual Method	499	515	2,691	5,398
Allowance for loan losses: Total	122,269	153,765	122,269	153,765	125,796	145,009	187,940	216,012
Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Impaired Financing Receivable, Average Recorded Investment	36	6,284	4,109	7,333
Impaired Financing Receivable, Interest Income, Accrual Method	177	384	692	1,315
Allowance for loan losses: Individually evaluated for impairment	(11,014)		(11,014)			(9,059)
Allowance for loan losses: Collectively evaluated for impairment	35,010		35,010			37,508
Allowance for loan losses: Purchased loans with evidence of credit deterioration	450		450			573
Allowance for loan losses: Total	46,474	44,467	46,474	44,467	$ 45,809	47,140	$ 45,002	$ 61,066
Outstanding loan balances: Individually evaluated for impairment	92,612		92,612			95,267
Outstanding loan balances: Collectively evaluated for impairment	8,503,160		8,503,160			8,395,371
Financing Receivable Allowance For Credit Losses and Receivables Acquired With Deteriorated Credit Quality	10,978		10,978			15,648
Total loans	8,606,750		8,606,750			8,506,286
Commercial Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Impaired Financing Receivable, Average Recorded Investment	330,814	427,308	295,044	424,853
Impaired Financing Receivable, Interest Income, Accrual Method	4,066	6,849	15,231	22,593
Term [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Impaired Financing Receivable, Average Recorded Investment	119,694	225,536	124,446	248,587
Impaired Financing Receivable, Interest Income, Accrual Method	3,705	5,670	13,383	26,118
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Impaired Financing Receivable, Average Recorded Investment	151,200	285,271	156,366	310,991
Impaired Financing Receivable, Interest Income, Accrual Method	4,204	6,185	16,074	31,516
Allowance for loan losses: Individually evaluated for impairment	(2,898)		(2,898)			(4,027)
Allowance for loan losses: Collectively evaluated for impairment	119,286		119,286			140,090
Allowance for loan losses: Purchased loans with evidence of credit deterioration	85		85			892
Allowance for loan losses: Total	122,269		122,269			145,009
Outstanding loan balances: Individually evaluated for impairment	122,063		122,063			167,435
Outstanding loan balances: Collectively evaluated for impairment	10,122,697		10,122,697			9,861,862
Financing Receivable Allowance For Credit Losses and Receivables Acquired With Deteriorated Credit Quality	57,963		57,963			83,711
Total loans	10,302,723		10,302,723			$ 10,113,008
Home Equity Line of Credit [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Impaired Financing Receivable, Average Recorded Investment	25,095	26,328	24,329	25,756
Impaired Financing Receivable, Interest Income, Accrual Method	401	369	1,206	1,139
One Through Four Family Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Impaired Financing Receivable, Average Recorded Investment	90,240	81,116	91,671	81,168
Impaired Financing Receivable, Interest Income, Accrual Method	398	556	1,803	1,583
Construction And Other Consumer Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Impaired Financing Receivable, Average Recorded Investment	5,540	3,226	2,342	3,112
Impaired Financing Receivable, Interest Income, Accrual Method	32	43	91	115
Revolving Credit Facility [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Impaired Financing Receivable, Average Recorded Investment	0	0	1	3
Impaired Financing Receivable, Interest Income, Accrual Method	1	1	101	2
Consumer Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Impaired Financing Receivable, Average Recorded Investment	120,911	116,954	122,452	117,372
Impaired Financing Receivable, Interest Income, Accrual Method	1,009	1,353	3,893	4,154
Municipal [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Impaired Financing Receivable, Average Recorded Investment	978	8,798	1,007	9,343
Impaired Financing Receivable, Interest Income, Accrual Method	$ 0	$ 0	$ 0	$ 0