Loans And Allowance For Credit Losses (Summary Of Past Due Loans (Accruing And Nonaccruing)) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014
Financing Receivable, Allowance for Credit Losses [Line Items]
Current	$ 39,880,380		$ 39,796,072
30-89 days past due	142,643		104,491
90+ days past due	157,091		163,095
Total past due	299,734		267,586
Total loans	40,180,114		40,063,658
Accruing loans 90+ days past due	31,552		29,228
Financing Receivable Recorded Investment Nonaccrual Status That Are Current	211,126	[1]	154,778	[1]
Financing Receivable, Recorded Investment, Nonaccrual Status	382,066		306,648
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	21,535,990		21,444,364
Commercial Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current	21,364,561		21,298,184
30-89 days past due	89,589		57,702
90+ days past due	81,840		88,478
Total past due	171,429		146,180
Total loans	21,535,990		21,444,364
Accruing loans 90+ days past due	5,216		8,011
Financing Receivable Recorded Investment Nonaccrual Status That Are Current	151,717	[1]	105,360	[1]
Financing Receivable, Recorded Investment, Nonaccrual Status	262,382		194,185
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	10,133,071		10,113,008
Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	8,511,053		8,506,286
Consumer Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current	8,450,473		8,442,742
30-89 days past due	31,732		29,663
90+ days past due	28,848		33,881
Total past due	60,580		63,544
Total loans	8,511,053		8,506,286
Accruing loans 90+ days past due	1,836		1,425
Financing Receivable Recorded Investment Nonaccrual Status That Are Current	24,673	[1]	23,150	[1]
Financing Receivable, Recorded Investment, Nonaccrual Status	60,066		63,476
Commercial And Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current	13,182,403		13,092,731
30-89 days past due	42,881		28,295
90+ days past due	38,808		41,929
Total past due	81,689		70,224
Total loans	13,264,092		13,162,955
Accruing loans 90+ days past due	2,969		4,677
Financing Receivable Recorded Investment Nonaccrual Status That Are Current	109,978	[1]	64,385	[1]
Financing Receivable, Recorded Investment, Nonaccrual Status	163,499		105,591
Leasing [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current	406,902		408,724
30-89 days past due	208		225
90+ days past due	27		25
Total past due	235		250
Total loans	407,137		408,974
Accruing loans 90+ days past due	0		0
Financing Receivable Recorded Investment Nonaccrual Status That Are Current	197	[1]	270	[1]
Financing Receivable, Recorded Investment, Nonaccrual Status	247		295
Owner Occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current	7,222,254		7,275,842
30-89 days past due	44,380		29,182
90+ days past due	43,005		46,524
Total past due	87,385		75,706
Total loans	7,309,639		7,351,548
Accruing loans 90+ days past due	2,247		3,334
Financing Receivable Recorded Investment Nonaccrual Status That Are Current	40,515	[1]	39,649	[1]
Financing Receivable, Recorded Investment, Nonaccrual Status	97,609		87,243
Municipal [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current	553,002		520,887
30-89 days past due	2,120		0
90+ days past due	0		0
Total past due	2,120		0
Total loans	555,122		520,887
Accruing loans 90+ days past due	0		0
Financing Receivable Recorded Investment Nonaccrual Status That Are Current	1,027	[1]	1,056	[1]
Financing Receivable, Recorded Investment, Nonaccrual Status	1,027		1,056
Commercial Real Estate Construction Financing Receivable [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current	2,027,240		1,972,206
30-89 days past due	4,114		2,711
90+ days past due	13,287		11,491
Total past due	17,401		14,202
Total loans	2,044,641		1,986,408
Accruing loans 90+ days past due	2,590		92
Financing Receivable Recorded Investment Nonaccrual Status That Are Current	11,338	[1]	12,481	[1]
Financing Receivable, Recorded Investment, Nonaccrual Status	22,101		23,880
Term [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current	8,038,106		8,082,940
30-89 days past due	17,208		14,415
90+ days past due	33,116		29,245
Total past due	50,324		43,660
Total loans	8,088,430		8,126,600
Accruing loans 90+ days past due	21,910		19,700
Financing Receivable Recorded Investment Nonaccrual Status That Are Current	23,398	[1]	13,787	[1]
Financing Receivable, Recorded Investment, Nonaccrual Status	37,517		25,107
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current	10,065,346		10,055,146
30-89 days past due	21,322		17,126
90+ days past due	46,403		40,736
Total past due	67,725		57,862
Total loans	10,133,071		10,113,008
Accruing loans 90+ days past due	24,500		19,792
Financing Receivable Recorded Investment Nonaccrual Status That Are Current	34,736	[1]	26,268	[1]
Financing Receivable, Recorded Investment, Nonaccrual Status	59,618		48,987
Home Equity Line of Credit [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current	2,302,583		2,309,967
30-89 days past due	4,522		4,503
90+ days past due	7,701		6,680
Total past due	12,223		11,183
Total loans	2,314,806		2,321,150
Accruing loans 90+ days past due	0		1
Financing Receivable Recorded Investment Nonaccrual Status That Are Current	1,103	[1]	1,779	[1]
Financing Receivable, Recorded Investment, Nonaccrual Status	10,337		11,430
One Through Four Family Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current	5,181,356		5,163,610
30-89 days past due	12,780		12,416
90+ days past due	18,827		24,856
Total past due	31,607		37,272
Total loans	5,212,963		5,200,882
Accruing loans 90+ days past due	268		318
Financing Receivable Recorded Investment Nonaccrual Status That Are Current	22,781	[1]	20,599	[1]
Financing Receivable, Recorded Investment, Nonaccrual Status	48,078		49,861
Construction And Other Consumer Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current	361,483		359,723
30-89 days past due	10,682		9,675
90+ days past due	1,170		1,144
Total past due	11,852		10,819
Total loans	373,335		370,542
Accruing loans 90+ days past due	556		160
Financing Receivable Recorded Investment Nonaccrual Status That Are Current	664	[1]	608	[1]
Financing Receivable, Recorded Investment, Nonaccrual Status	1,301		1,735
Revolving Credit Facility [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current	402,775		397,882
30-89 days past due	2,859		2,425
90+ days past due	1,089		1,045
Total past due	3,948		3,470
Total loans	406,723		401,352
Accruing loans 90+ days past due	951		946
Financing Receivable Recorded Investment Nonaccrual Status That Are Current	98	[1]	80	[1]
Financing Receivable, Recorded Investment, Nonaccrual Status	318		196
Consumer Other Financing Receivable [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current	202,276		211,560
30-89 days past due	889		644
90+ days past due	61		156
Total past due	950		800
Total loans	203,226		212,360
Accruing loans 90+ days past due	61		0
Financing Receivable Recorded Investment Nonaccrual Status That Are Current	27	[1]	84	[1]
Financing Receivable, Recorded Investment, Nonaccrual Status	$ 32		$ 254

[1] Represents nonaccrual loans that are not past due more than 30 days; however, full payment of principal and interest is still not expected.