Loans and Allowance for Loan Losses (Schedule Of Current, Accruing Past Due And Nonaccrual Loans) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016
Valuation and Qualifying Accounts Disclosure [Line Items]
Current	$ 24,230,445	$ 23,663,898
Accruing 30-89 Days Past Due	62,238	61,971
Accruing 90 Days or Greater Past Due	4,550	3,135
Total Accruing Past Due	66,788	65,106
Non-accrual	159,317	153,378
Total loans	24,456,550	23,882,382	$ 23,088,535
Deferred fees and costs, net	26,000	26,000	$ 27,600
Total commercial real estate
Valuation and Qualifying Accounts Disclosure [Line Items]
Current	7,376,691	7,326,161
Accruing 30-89 Days Past Due	14,103	9,037
Accruing 90 Days or Greater Past Due	299	161
Total Accruing Past Due	14,402	9,198
Non-accrual	23,178	30,615
Total loans	7,414,271	7,365,974
Investment properties
Valuation and Qualifying Accounts Disclosure [Line Items]
Current	6,028,397	5,861,198
Accruing 30-89 Days Past Due	3,482	2,795
Accruing 90 Days or Greater Past Due	72	0
Total Accruing Past Due	3,554	2,795
Non-accrual	3,712	5,268
Total loans	6,035,663	5,869,261
1-4 family properties
Valuation and Qualifying Accounts Disclosure [Line Items]
Current	818,327	873,231
Accruing 30-89 Days Past Due	8,657	4,801
Accruing 90 Days or Greater Past Due	101	161
Total Accruing Past Due	8,758	4,962
Non-accrual	8,535	9,114
Total loans	835,620	887,307
Land and development
Valuation and Qualifying Accounts Disclosure [Line Items]
Current	529,967	591,732
Accruing 30-89 Days Past Due	1,964	1,441
Accruing 90 Days or Greater Past Due	126	0
Total Accruing Past Due	2,090	1,441
Non-accrual	10,931	16,233
Total loans	542,988	609,406
Total commercial and industrial
Valuation and Qualifying Accounts Disclosure [Line Items]
Current	11,630,913	11,447,947
Accruing 30-89 Days Past Due	23,961	27,455
Accruing 90 Days or Greater Past Due	1,566	964
Total Accruing Past Due	25,527	28,419
Non-accrual	94,468	75,577
Total loans	11,750,908	11,551,943
Commercial, financial and agricultural
Valuation and Qualifying Accounts Disclosure [Line Items]
Current	6,915,588	6,846,591
Accruing 30-89 Days Past Due	14,670	9,542
Accruing 90 Days or Greater Past Due	765	720
Total Accruing Past Due	15,435	10,262
Non-accrual	69,550	59,074
Total loans	7,000,573	6,915,927
Owner-occupied
Valuation and Qualifying Accounts Disclosure [Line Items]
Current	4,715,325	4,601,356
Accruing 30-89 Days Past Due	9,291	17,913
Accruing 90 Days or Greater Past Due	801	244
Total Accruing Past Due	10,092	18,157
Non-accrual	24,918	16,503
Total loans	4,750,335	4,636,016
Total consumer
Valuation and Qualifying Accounts Disclosure [Line Items]
Current	5,222,841	4,889,790
Accruing 30-89 Days Past Due	24,174	25,479
Accruing 90 Days or Greater Past Due	2,685	2,010
Total Accruing Past Due	26,859	27,489
Non-accrual	41,671	47,186
Total loans	5,291,371	4,964,465
Home equity lines
Valuation and Qualifying Accounts Disclosure [Line Items]
Current	1,533,528	1,585,228
Accruing 30-89 Days Past Due	8,286	10,013
Accruing 90 Days or Greater Past Due	705	473
Total Accruing Past Due	8,991	10,486
Non-accrual	20,648	21,551
Total loans	1,563,167	1,617,265
Consumer mortgages
Valuation and Qualifying Accounts Disclosure [Line Items]
Current	2,444,866	2,265,966
Accruing 30-89 Days Past Due	7,141	7,876
Accruing 90 Days or Greater Past Due	623	81
Total Accruing Past Due	7,764	7,957
Non-accrual	18,035	22,681
Total loans	2,470,665	2,296,604
Credit cards
Valuation and Qualifying Accounts Disclosure [Line Items]
Current	223,092	229,177
Accruing 30-89 Days Past Due	1,550	1,819
Accruing 90 Days or Greater Past Due	1,258	1,417
Total Accruing Past Due	2,808	3,236
Non-accrual	0	0
Total loans	225,900	232,413
Other consumer loans
Valuation and Qualifying Accounts Disclosure [Line Items]
Current	1,021,355	809,419
Accruing 30-89 Days Past Due	7,197	5,771
Accruing 90 Days or Greater Past Due	99	39
Total Accruing Past Due	7,296	5,810
Non-accrual	2,988	2,954
Total loans	$ 1,031,639	$ 818,183