Loans And Allowance For Loan Losses (Schedule Of Current, Accruing Past Due And Nonaccrual Loans) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Valuation and Qualifying Accounts Disclosure [Line Items]
Current	$ 24,645,203	$ 23,663,898
Accruing 30-89 Days Past Due	47,617	61,971
Accruing 90 Days or Greater Past Due	4,414	3,135
Total Accruing Past Due	52,031	65,106
Non-accrual	115,561	153,378
Total loans	24,812,795	23,882,382
Deferred fees and costs, net	25,331	25,991	$ 30,100
Total commercial real estate
Valuation and Qualifying Accounts Disclosure [Line Items]
Current	6,914,819	7,334,299
Accruing 30-89 Days Past Due	7,660	9,037
Accruing 90 Days or Greater Past Due	359	161
Total Accruing Past Due	8,019	9,198
Non-accrual	12,450	30,615
Total loans	6,935,288	7,374,112
Total commercial real estate | Investment properties
Valuation and Qualifying Accounts Disclosure [Line Items]
Current	5,663,665	5,861,198
Accruing 30-89 Days Past Due	2,506	2,795
Accruing 90 Days or Greater Past Due	90	0
Total Accruing Past Due	2,596	2,795
Non-accrual	3,804	5,268
Total loans	5,670,065	5,869,261
Total commercial real estate | 1-4 family properties
Valuation and Qualifying Accounts Disclosure [Line Items]
Current	775,023	874,477
Accruing 30-89 Days Past Due	3,545	4,801
Accruing 90 Days or Greater Past Due	202	161
Total Accruing Past Due	3,747	4,962
Non-accrual	2,849	9,114
Total loans	781,619	888,553
Total commercial real estate | Land and development
Valuation and Qualifying Accounts Disclosure [Line Items]
Current	476,131	598,624
Accruing 30-89 Days Past Due	1,609	1,441
Accruing 90 Days or Greater Past Due	67	0
Total Accruing Past Due	1,676	1,441
Non-accrual	5,797	16,233
Total loans	483,604	616,298
Total commercial and industrial
Valuation and Qualifying Accounts Disclosure [Line Items]
Current	11,927,277	11,439,810
Accruing 30-89 Days Past Due	18,094	27,455
Accruing 90 Days or Greater Past Due	1,495	964
Total Accruing Past Due	19,589	28,419
Non-accrual	76,784	75,577
Total loans	12,023,650	11,543,806
Total commercial and industrial | Commercial, financial and agricultural
Valuation and Qualifying Accounts Disclosure [Line Items]
Current	7,097,127	6,839,700
Accruing 30-89 Days Past Due	11,214	9,542
Accruing 90 Days or Greater Past Due	1,016	720
Total Accruing Past Due	12,230	10,262
Non-accrual	70,130	59,074
Total loans	7,179,487	6,909,036
Total commercial and industrial | Owner-occupied
Valuation and Qualifying Accounts Disclosure [Line Items]
Current	4,830,150	4,600,110
Accruing 30-89 Days Past Due	6,880	17,913
Accruing 90 Days or Greater Past Due	479	244
Total Accruing Past Due	7,359	18,157
Non-accrual	6,654	16,503
Total loans	4,844,163	4,634,770
Total consumer
Valuation and Qualifying Accounts Disclosure [Line Items]
Current	5,803,107	4,889,789
Accruing 30-89 Days Past Due	21,863	25,479
Accruing 90 Days or Greater Past Due	2,560	2,010
Total Accruing Past Due	24,423	27,489
Non-accrual	26,327	47,186
Total loans	5,853,857	4,964,464
Total consumer | Home equity lines
Valuation and Qualifying Accounts Disclosure [Line Items]
Current	1,490,808	1,585,228
Accruing 30-89 Days Past Due	5,629	10,013
Accruing 90 Days or Greater Past Due	335	473
Total Accruing Past Due	5,964	10,486
Non-accrual	17,455	21,551
Total loans	1,514,227	1,617,265
Total consumer | Consumer mortgages
Valuation and Qualifying Accounts Disclosure [Line Items]
Current	2,622,061	2,265,966
Accruing 30-89 Days Past Due	3,971	7,876
Accruing 90 Days or Greater Past Due	268	81
Total Accruing Past Due	4,239	7,957
Non-accrual	7,203	22,681
Total loans	2,633,503	2,296,604
Total consumer | Credit cards
Valuation and Qualifying Accounts Disclosure [Line Items]
Current	229,015	229,177
Accruing 30-89 Days Past Due	1,930	1,819
Accruing 90 Days or Greater Past Due	1,731	1,417
Total Accruing Past Due	3,661	3,236
Non-accrual	0	0
Total loans	232,676	232,413
Total consumer | Other consumer loans
Valuation and Qualifying Accounts Disclosure [Line Items]
Current	1,461,223	809,418
Accruing 30-89 Days Past Due	10,333	5,771
Accruing 90 Days or Greater Past Due	226	39
Total Accruing Past Due	10,559	5,810
Non-accrual	1,669	2,954
Total loans	$ 1,473,451	$ 818,182