Loans and Allowance for Loan Losses (Schedule Of Current, Accruing Past Due And Nonaccrual Loans) (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	$ 25,134,056	$ 24,787,464
Non-accrual	117,328	115,561
Total loans	25,156,773	24,812,795	$ 24,456,550
Deferred fees and costs, net	22,700	25,300	$ 26,000
Total commercial and industrial
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Non-accrual	87,307	76,784
Total loans	12,275,472	12,023,650
Total commercial and industrial | Commercial, financial and agricultural
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Non-accrual	81,231	70,130
Total loans	7,271,080	7,179,487
Total commercial and industrial | Owner-occupied
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Non-accrual	6,076	6,654
Total loans	5,004,392	4,844,163
Total commercial real estate
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Non-accrual	9,609	12,450
Total loans	6,644,171	6,935,288
Total commercial real estate | Investment properties
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Non-accrual	1,738	3,804
Total loans	5,509,596	5,670,065
Total commercial real estate | 1-4 family properties
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Non-accrual	3,247	2,849
Total loans	720,710	781,619
Total commercial real estate | Land and development
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Non-accrual	4,624	5,797
Total loans	413,865	483,604
Total consumer
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Non-accrual	20,412	26,327
Total loans	6,237,130	5,853,857
Total consumer | Home equity lines
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Non-accrual	14,265	17,455
Total loans	1,453,855	1,514,227
Total consumer | Consumer mortgages
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Non-accrual	4,822	7,203
Total loans	2,750,935	2,633,503
Total consumer | Credit cards
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Non-accrual	0	0
Total loans	238,424	232,676
Total consumer | Other consumer loans
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Non-accrual	1,325	1,669
Total loans	1,793,916	1,473,451
Current
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	24,983,831	24,645,203
Current | Total commercial and industrial
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	12,164,915	11,927,277
Current | Total commercial and industrial | Commercial, financial and agricultural
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	7,170,877	7,097,127
Current | Total commercial and industrial | Owner-occupied
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	4,994,038	4,830,150
Current | Total commercial real estate
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	6,628,202	6,914,819
Current | Total commercial real estate | Investment properties
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	5,505,409	5,663,665
Current | Total commercial real estate | 1-4 family properties
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	715,154	775,023
Current | Total commercial real estate | Land and development
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	407,639	476,131
Current | Total consumer
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	6,190,714	5,803,107
Current | Total consumer | Home equity lines
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	1,430,778	1,490,808
Current | Total consumer | Consumer mortgages
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	2,741,064	2,622,061
Current | Total consumer | Credit cards
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	235,406	229,015
Current | Total consumer | Other consumer loans
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	1,783,466	1,461,223
Accruing 30-89 Days Past Due
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	52,392	47,617
Accruing 30-89 Days Past Due | Total commercial and industrial
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	22,605	18,094
Accruing 30-89 Days Past Due | Total commercial and industrial | Commercial, financial and agricultural
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	18,425	11,214
Accruing 30-89 Days Past Due | Total commercial and industrial | Owner-occupied
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	4,180	6,880
Accruing 30-89 Days Past Due | Total commercial real estate
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	5,749	7,660
Accruing 30-89 Days Past Due | Total commercial real estate | Investment properties
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	1,838	2,506
Accruing 30-89 Days Past Due | Total commercial real estate | 1-4 family properties
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	2,309	3,545
Accruing 30-89 Days Past Due | Total commercial real estate | Land and development
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	1,602	1,609
Accruing 30-89 Days Past Due | Total consumer
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	24,038	21,863
Accruing 30-89 Days Past Due | Total consumer | Home equity lines
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	8,450	5,629
Accruing 30-89 Days Past Due | Total consumer | Consumer mortgages
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	4,805	3,971
Accruing 30-89 Days Past Due | Total consumer | Credit cards
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	1,793	1,930
Accruing 30-89 Days Past Due | Total consumer | Other consumer loans
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	8,990	10,333
Accruing 90 Days or Greater Past Due
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	3,222	4,414
Accruing 90 Days or Greater Past Due | Total commercial and industrial
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	645	1,495
Accruing 90 Days or Greater Past Due | Total commercial and industrial | Commercial, financial and agricultural
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	547	1,016
Accruing 90 Days or Greater Past Due | Total commercial and industrial | Owner-occupied
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	98	479
Accruing 90 Days or Greater Past Due | Total commercial real estate
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	611	359
Accruing 90 Days or Greater Past Due | Total commercial real estate | Investment properties
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	611	90
Accruing 90 Days or Greater Past Due | Total commercial real estate | 1-4 family properties
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	0	202
Accruing 90 Days or Greater Past Due | Total commercial real estate | Land and development
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	0	67
Accruing 90 Days or Greater Past Due | Total consumer
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	1,966	2,560
Accruing 90 Days or Greater Past Due | Total consumer | Home equity lines
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	362	335
Accruing 90 Days or Greater Past Due | Total consumer | Consumer mortgages
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	244	268
Accruing 90 Days or Greater Past Due | Total consumer | Credit cards
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	1,225	1,731
Accruing 90 Days or Greater Past Due | Total consumer | Other consumer loans
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	135	226
Total Accruing Past Due
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	55,614	52,031
Total Accruing Past Due | Total commercial and industrial
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	23,250	19,589
Total Accruing Past Due | Total commercial and industrial | Commercial, financial and agricultural
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	18,972	12,230
Total Accruing Past Due | Total commercial and industrial | Owner-occupied
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	4,278	7,359
Total Accruing Past Due | Total commercial real estate
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	6,360	8,019
Total Accruing Past Due | Total commercial real estate | Investment properties
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	2,449	2,596
Total Accruing Past Due | Total commercial real estate | 1-4 family properties
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	2,309	3,747
Total Accruing Past Due | Total commercial real estate | Land and development
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	1,602	1,676
Total Accruing Past Due | Total consumer
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	26,004	24,423
Total Accruing Past Due | Total consumer | Home equity lines
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	8,812	5,964
Total Accruing Past Due | Total consumer | Consumer mortgages
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	5,049	4,239
Total Accruing Past Due | Total consumer | Credit cards
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	3,018	3,661
Total Accruing Past Due | Total consumer | Other consumer loans
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans and leases receivables	$ 9,125	$ 10,559