Loans And Allowance For Credit Losses (Summary Of Outstanding Loan Balances (Accruing And Nonaccruing) Categorized By Credit Quality Indicators) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans held for sale	$ 164,374	$ 171,328
Commercial and industrial	12,805,303	12,481,083
Leasing	415,205	387,929
Owner occupied	7,386,414	7,437,195
Municipal	522,327	449,418
Total commercial	21,129,249	20,755,625
Construction and land development	2,340,249	2,182,821
Term	7,968,625	8,005,837
Total commercial real estate	10,308,874	10,188,658
Home equity credit line	2,204,174	2,133,120
1-4 family residential	4,827,067	4,736,665
Construction and other consumer real estate	338,170	324,922
Bankcard and other revolving plans	376,366	356,240
Other	195,895	197,864
Total consumer	7,941,672	7,748,811
FDIC-supported loans	250,568	350,271
Total loans	39,630,363	39,043,365
FDIC-Supported Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
FDIC-supported loans	250,568
FDIC-supported loans		350,271
Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Home equity credit line	2,204,174	2,133,120
1-4 family residential	4,827,067	4,736,665
Construction and other consumer real estate	338,170	324,922
Bankcard and other revolving plans	376,366	356,240
Other	195,895	197,864
Total consumer	7,941,672	7,748,811
Total loans	7,941,672	7,748,811
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Term	7,968,625	8,005,837
Total commercial real estate	10,308,874	10,188,658
Total loans	10,308,874	10,188,658
Commercial Real Estate Construction Financing Receivable [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Construction and land development	2,340,249	2,182,821
Total loans	2,340,249	2,182,821
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Commercial and industrial	12,805,303	12,481,083
Leasing	415,205	387,929
Owner occupied	7,386,414	7,437,195
Municipal	522,327	449,418
Total commercial	21,129,249	20,755,625
Total loans	21,129,249	20,755,625
Pass [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans held for sale	148,381	171,328
Total loans	37,749,858	37,009,767
Pass [Member] | FDIC-Supported Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
FDIC-supported loans	153,253
FDIC-supported loans		232,893
Pass [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Home equity credit line	2,182,585	2,111,475
1-4 family residential	4,767,970	4,668,841
Construction and other consumer real estate	332,101	313,881
Bankcard and other revolving plans	374,281	353,618
Other	195,323	196,770
Total consumer	7,852,260	7,644,585
Pass [Member] | Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Term	7,634,361	7,569,472
Total commercial real estate	9,914,307	9,677,300
Pass [Member] | Commercial Real Estate Construction Financing Receivable [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Construction and land development	2,279,946	2,107,828
Pass [Member] | Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Commercial and industrial	12,105,752	11,807,825
Leasing	408,963	380,268
Owner occupied	6,801,947	6,827,464
Municipal	513,376	439,432
Total commercial	19,830,038	19,454,989
Special Mention [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans held for sale	15,993	0
Total loans	576,428	700,374
Special Mention [Member] | FDIC-Supported Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
FDIC-supported loans	17,286
FDIC-supported loans		22,532
Special Mention [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Home equity credit line	0	0
1-4 family residential	0	0
Construction and other consumer real estate	0	0
Bankcard and other revolving plans	0	0
Other	0	0
Total consumer	0	0
Special Mention [Member] | Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Term	107,039	172,856
Total commercial real estate	116,373	187,866
Special Mention [Member] | Commercial Real Estate Construction Financing Receivable [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Construction and land development	9,334	15,010
Special Mention [Member] | Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Commercial and industrial	237,639	303,598
Leasing	3,801	2,050
Owner occupied	201,329	184,328
Municipal	0	0
Total commercial	442,769	489,976
Total Allowance [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans held for sale	0	0
Total loans	675,907	746,291
Total Allowance [Member] | FDIC-Supported Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
FDIC-supported loans	3,877
FDIC-supported loans		6,918
Total Allowance [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total consumer	44,535	60,865
Total Allowance [Member] | Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total commercial real estate	187,261	213,363
Total Allowance [Member] | Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total commercial	440,234	465,145
Doubtful [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans held for sale	0	0
Total loans	2,745	9,269
Doubtful [Member] | FDIC-Supported Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
FDIC-supported loans	0	0
Doubtful [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Home equity credit line	0	0
1-4 family residential	0	0
Construction and other consumer real estate	0	0
Bankcard and other revolving plans	0	0
Other	0	0
Total consumer	0	0
Doubtful [Member] | Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Term	0	0
Total commercial real estate	0	0
Doubtful [Member] | Commercial Real Estate Construction Financing Receivable [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Construction and land development	0	0
Doubtful [Member] | Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Commercial and industrial	2,745	9,269
Leasing	0	0
Owner occupied	0	0
Municipal	0	0
Total commercial	2,745	9,269
Substandard [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans held for sale	0	0
Total loans	1,301,332	1,323,955
Substandard [Member] | FDIC-Supported Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
FDIC-supported loans	80,029
FDIC-supported loans		94,846
Substandard [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Home equity credit line	21,589	21,645
1-4 family residential	59,097	67,824
Construction and other consumer real estate	6,069	11,041
Bankcard and other revolving plans	2,085	2,622
Other	572	1,094
Total consumer	89,412	104,226
Substandard [Member] | Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Term	227,225	263,509
Total commercial real estate	278,194	323,492
Substandard [Member] | Commercial Real Estate Construction Financing Receivable [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Construction and land development	50,969	59,983
Substandard [Member] | Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Commercial and industrial	459,167	360,391
Leasing	2,441	5,611
Owner occupied	383,138	425,403
Municipal	8,951	9,986
Total commercial	$ 853,697	$ 801,391