Loans And Allowance For Loan Losses (Schedule Of Allowances For Loan Losses And Recorded Investment In Loans) (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				$ 249,268,000				$ 251,758,000	$ 249,268,000	$ 251,758,000	$ 252,496,000
Charge-offs									(74,054,000)	(90,419,000)	(57,960,000)
Recoveries									23,644,000	20,744,000	29,222,000
Provision for loan losses	$ 12,149,000	$ 14,982,000	$ 11,790,000	12,776,000	$ 8,565,000	$ 39,686,000	$ 10,260,000	8,674,000	51,697,000	67,185,000	28,000,000
Ending balance	250,555,000				249,268,000				250,555,000	249,268,000	251,758,000
Ending balance: individually evaluated for impairment	13,549,000				14,908,000				13,549,000	14,908,000	18,111,000
Ending balance: collectively evaluated for impairment	237,006,000				234,360,000				237,006,000	234,360,000	233,647,000
Total loans	25,970,716,000				24,812,795,000				25,970,716,000	24,812,795,000	23,882,382,000
Ending balance: individually evaluated for impairment	166,926,000				200,286,000				166,926,000	200,286,000	249,496,000
Ending balance: collectively evaluated for impairment	25,803,790,000				24,612,509,000				25,803,790,000	24,612,509,000	23,632,886,000
Deferred fees and costs, net	24,143,000				25,331,000				24,143,000	25,331,000	26,000,000
Purchased credit-impaired loans									0	0	0
Allowance for purchased credit-impaired loans									0	0	0
Total commercial and industrial
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				126,803,000				125,778,000	126,803,000	125,778,000	122,989,000
Charge-offs									(48,775,000)	(49,244,000)	(25,039,000)
Recoveries									7,165,000	6,685,000	9,071,000
Provision for loan losses									47,930,000	43,584,000	18,757,000
Ending balance	133,123,000				126,803,000				133,123,000	126,803,000	125,778,000
Ending balance: individually evaluated for impairment	10,207,000				9,515,000				10,207,000	9,515,000	8,384,000
Ending balance: collectively evaluated for impairment	122,916,000				117,288,000				122,916,000	117,288,000	117,394,000
Total loans	12,781,206,000				12,023,650,000				12,781,206,000	12,023,650,000	11,543,806,000
Ending balance: individually evaluated for impairment	105,422,000				111,334,000				105,422,000	111,334,000	120,560,000
Ending balance: collectively evaluated for impairment	12,675,784,000				11,912,316,000				12,675,784,000	11,912,316,000	11,423,246,000
Total commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				74,998,000				81,816,000	74,998,000	81,816,000	87,133,000
Charge-offs									(4,408,000)	(12,193,000)	(18,216,000)
Recoveries									10,188,000	8,026,000	15,226,000
Provision for loan losses									(11,982,000)	(2,651,000)	(2,327,000)
Ending balance	68,796,000				74,998,000				68,796,000	74,998,000	81,816,000
Ending balance: individually evaluated for impairment	2,598,000				4,240,000				2,598,000	4,240,000	7,916,000
Ending balance: collectively evaluated for impairment	66,198,000				70,758,000				66,198,000	70,758,000	73,900,000
Total loans	6,564,491,000				6,935,288,000				6,564,491,000	6,935,288,000	7,374,112,000
Ending balance: individually evaluated for impairment	33,198,000				56,896,000				33,198,000	56,896,000	91,410,000
Ending balance: collectively evaluated for impairment	6,531,293,000				6,878,392,000				6,531,293,000	6,878,392,000	7,282,702,000
Total consumer
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance				$ 47,467,000				$ 44,164,000	47,467,000	44,164,000	42,374,000
Charge-offs									(20,871,000)	(28,982,000)	(14,705,000)
Recoveries									6,291,000	6,033,000	4,925,000
Provision for loan losses									15,749,000	26,252,000	11,570,000
Ending balance	48,636,000				47,467,000				48,636,000	47,467,000	44,164,000
Ending balance: individually evaluated for impairment	744,000				1,153,000				744,000	1,153,000	1,811,000
Ending balance: collectively evaluated for impairment	47,892,000				46,314,000				47,892,000	46,314,000	42,353,000
Total loans	6,625,019,000				5,853,857,000				6,625,019,000	5,853,857,000	4,964,464,000
Ending balance: individually evaluated for impairment	28,306,000				32,056,000				28,306,000	32,056,000	37,526,000
Ending balance: collectively evaluated for impairment	$ 6,596,713,000				$ 5,821,801,000				$ 6,596,713,000	$ 5,821,801,000	$ 4,926,938,000