Loans And Allowance For Loan Losses (Schedule Of Allowances For Loan Losses And Recorded Investment In Loans) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				$ 252,496				$ 261,317	$ 252,496	$ 261,317	$ 307,560
Allowance for loan losses of sold Memphis loans											(1,019)
Charge-offs									(57,960)	(57,339)	(113,538)
Recoveries									29,222	29,508	34,483
Provision for loan losses	$ 6,259	$ 5,671	$ 6,693	9,377	$ 5,021	$ 2,956	$ 6,636	4,397	28,000	19,010	33,831
Ending balance	251,758				252,496				251,758	252,496	261,317
Ending balance: individually evaluated for impairment	18,111				30,435				18,111	30,435	33,476
Ending balance: collectively evaluated for impairment	233,647				222,061				233,647	222,061	227,841
Ending balance: total loans	23,882,382				22,459,664				23,882,382	22,459,664	21,128,489
Ending balance: individually evaluated for impairment	249,496				301,800				249,496	301,800	442,148
Ending balance: collectively evaluated for impairment	23,632,886				22,157,864				23,632,886	22,157,864	20,686,341
Deferred fees and costs, net	25,991				30,099				25,991	30,099	30,800
Commercial Real Estate [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				87,133				101,471	87,133	101,471	127,646
Allowance for loan losses of sold Memphis loans											(281)
Charge-offs									(18,216)	(13,998)	(49,716)
Recoveries									15,226	13,644	11,787
Provision for loan losses									(2,327)	(13,984)	12,035
Ending balance	81,816				87,133				81,816	87,133	101,471
Ending balance: individually evaluated for impairment	7,916				18,969				7,916	18,969	21,755
Ending balance: collectively evaluated for impairment	73,900				68,164				73,900	68,164	79,716
Ending balance: total loans	7,365,974				7,394,768				7,365,974	7,394,768	6,926,602
Ending balance: individually evaluated for impairment	91,410				157,958				91,410	157,958	251,536
Ending balance: collectively evaluated for impairment	7,274,564				7,236,810				7,274,564	7,236,810	6,675,066
Commercial And Industrial [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				122,989				118,110	122,989	118,110	115,435
Allowance for loan losses of sold Memphis loans											(398)
Charge-offs									(25,039)	(22,583)	(38,941)
Recoveries									9,071	8,611	14,628
Provision for loan losses									18,757	18,851	27,386
Ending balance	125,778				122,989				125,778	122,989	118,110
Ending balance: individually evaluated for impairment	8,384				10,477				8,384	10,477	10,451
Ending balance: collectively evaluated for impairment	117,394				112,512				117,394	112,512	107,659
Ending balance: total loans	11,551,943				10,772,130				11,551,943	10,772,130	10,267,719
Ending balance: individually evaluated for impairment	120,560				105,599				120,560	105,599	146,026
Ending balance: collectively evaluated for impairment	11,431,383				10,666,531				11,431,383	10,666,531	10,121,693
Retail [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				42,374				41,736	42,374	41,736	41,479
Allowance for loan losses of sold Memphis loans											(340)
Charge-offs									(14,705)	(20,758)	(24,881)
Recoveries									4,925	7,253	8,068
Provision for loan losses									11,570	14,143	17,410
Ending balance	44,164				42,374				44,164	42,374	41,736
Ending balance: individually evaluated for impairment	1,811				989				1,811	989	1,270
Ending balance: collectively evaluated for impairment	42,353				41,385				42,353	41,385	40,466
Ending balance: total loans	4,964,465				4,292,766				4,964,465	4,292,766	3,934,168
Ending balance: individually evaluated for impairment	37,526				38,243				37,526	38,243	44,586
Ending balance: collectively evaluated for impairment	4,926,939				4,254,523				4,926,939	4,254,523	3,889,582
Unallocated [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				$ 0				$ 0	0	0	23,000
Charge-offs									0	0	0
Recoveries									0	0	0
Provision for loan losses									0	0	(23,000)
Ending balance	0				0				0	0	0
Ending balance: individually evaluated for impairment	0				0				0	0	0
Ending balance: collectively evaluated for impairment	0				0				0	0	0
Ending balance: total loans	0				0				0	0	0
Ending balance: individually evaluated for impairment	0				0				0	0	0
Ending balance: collectively evaluated for impairment	$ 0				$ 0				$ 0	$ 0	$ 0