Loans and Allowance for Loan Losses (Schedule Of Current, Accruing Past Due And Nonaccrual Loans) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Valuation and Qualifying Accounts Disclosure [Line Items]
Current	$ 22,545,515	$ 22,243,382
Accruing 30-89 Days Past Due	60,638	45,291
Accruing 90 Days or Greater Past Due	3,214	2,621
Total Accruing Past Due	63,852	47,912
Non-accrual	178,167	168,370
Total loans	22,787,534	22,459,664	$ 21,135,581
Deferred fees and costs, net	29,300	30,100	$ 29,400
Commercial Real Estate [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Current	7,520,193	7,308,461
Accruing 30-89 Days Past Due	15,768	9,223
Accruing 90 Days or Greater Past Due	234	135
Total Accruing Past Due	16,002	9,358
Non-accrual	55,523	57,647
Total loans	7,591,718	7,375,466
Investment Properties [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Current	5,954,011	5,726,307
Accruing 30-89 Days Past Due	9,484	2,284
Accruing 90 Days or Greater Past Due	0	0
Total Accruing Past Due	9,484	2,284
Non-accrual	23,749	23,040
Total loans	5,987,244	5,751,631
1-4 Family Properties [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Current	1,113,140	1,086,612
Accruing 30-89 Days Past Due	3,860	6,300
Accruing 90 Days or Greater Past Due	234	103
Total Accruing Past Due	4,094	6,403
Non-accrual	17,358	16,839
Total loans	1,134,592	1,109,854
Land Acquisition [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Current	453,042	495,542
Accruing 30-89 Days Past Due	2,424	639
Accruing 90 Days or Greater Past Due	0	32
Total Accruing Past Due	2,424	671
Non-accrual	14,416	17,768
Total loans	469,882	513,981
Commercial and Industrial [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Current	10,723,825	10,703,646
Accruing 30-89 Days Past Due	24,984	17,476
Accruing 90 Days or Greater Past Due	686	880
Total Accruing Past Due	25,670	18,356
Non-accrual	81,894	69,430
Total loans	10,831,389	10,791,432
Commercial, Financial and Agricultural [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Current	6,477,031	6,410,338
Accruing 30-89 Days Past Due	18,403	12,222
Accruing 90 Days or Greater Past Due	425	785
Total Accruing Past Due	18,828	13,007
Non-accrual	63,312	49,137
Total loans	6,559,171	6,472,482
Owner-Occupied [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Current	4,246,794	4,293,308
Accruing 30-89 Days Past Due	6,581	5,254
Accruing 90 Days or Greater Past Due	261	95
Total Accruing Past Due	6,842	5,349
Non-accrual	18,582	20,293
Total loans	4,272,218	4,318,950
Retail [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Current	4,301,497	4,231,275
Accruing 30-89 Days Past Due	19,886	18,592
Accruing 90 Days or Greater Past Due	2,294	1,606
Total Accruing Past Due	22,180	20,198
Non-accrual	40,750	41,293
Total loans	4,364,427	4,292,766
Home Equity Lines [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Current	1,647,483	1,667,552
Accruing 30-89 Days Past Due	5,321	5,882
Accruing 90 Days or Greater Past Due	170	0
Total Accruing Past Due	5,491	5,882
Non-accrual	16,432	16,480
Total loans	1,669,406	1,689,914
Consumer Mortgages [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Current	1,937,378	1,907,644
Accruing 30-89 Days Past Due	10,415	8,657
Accruing 90 Days or Greater Past Due	644	134
Total Accruing Past Due	11,059	8,791
Non-accrual	21,756	22,248
Total loans	1,970,193	1,938,683
Credit Cards [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Current	229,613	237,742
Accruing 30-89 Days Past Due	1,470	1,663
Accruing 90 Days or Greater Past Due	1,471	1,446
Total Accruing Past Due	2,941	3,109
Non-accrual	0	0
Total loans	232,554	240,851
Other Retail Loans [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Current	487,023	418,337
Accruing 30-89 Days Past Due	2,680	2,390
Accruing 90 Days or Greater Past Due	9	26
Total Accruing Past Due	2,689	2,416
Non-accrual	2,562	2,565
Total loans	$ 492,274	$ 423,318