Loans and Allowance for Loan Losses (Schedule Of Allowances For Loan Losses And Recorded Investment In Loans) (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance, allowance	$ 254,516,000	$ 253,371,000	$ 252,496,000	$ 261,317,000
Charge-offs	(15,771,000)	(10,604,000)	(27,086,000)	(31,228,000)
Recoveries	9,638,000	5,299,000	13,596,000	13,579,000
Provision for loan losses	6,693,000	6,636,000	16,070,000	11,034,000
Ending balance, allowance	255,076,000	254,702,000	255,076,000	254,702,000
Ending balance: individually evaluated for impairment, allowance	28,427,000	28,581,000	28,427,000	28,581,000
Ending balance: collectively evaluated for impairment, allowance	226,649,000	226,121,000	226,649,000	226,121,000
Total loans	23,088,535,000	21,523,990,000	23,088,535,000	21,523,990,000	$ 22,459,664,000
Ending balance: individually evaluated for impairment, loans	270,547,000	346,734,000	270,547,000	346,734,000
Ending balance: collectively evaluated for impairment, loans	22,817,988,000	21,177,256,000	22,817,988,000	21,177,256,000
Purchased credit-impaired loans	0	0	0	0
Allowance for purchased credit-impaired loans	0	0	0	0
Deferred fees and costs, net	27,600,000	29,100,000	27,600,000	29,100,000	$ 30,100,000
Commercial Real Estate [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance, allowance	84,557,000	94,208,000	87,133,000	101,471,000
Charge-offs	(7,455,000)	(2,957,000)	(9,277,000)	(10,397,000)
Recoveries	5,397,000	2,540,000	6,690,000	6,481,000
Provision for loan losses	(3,140,000)	(3,100,000)	(5,187,000)	(6,864,000)
Ending balance, allowance	79,359,000	90,691,000	79,359,000	90,691,000
Ending balance: individually evaluated for impairment, allowance	12,515,000	17,197,000	12,515,000	17,197,000
Ending balance: collectively evaluated for impairment, allowance	66,844,000	73,494,000	66,844,000	73,494,000
Total loans	7,507,695,000	7,071,595,000	7,507,695,000	7,071,595,000
Ending balance: individually evaluated for impairment, loans	112,954,000	193,230,000	112,954,000	193,230,000
Ending balance: collectively evaluated for impairment, loans	7,394,741,000	6,878,365,000	7,394,741,000	6,878,365,000
Commercial and Industrial [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance, allowance	124,878,000	117,806,000	122,989,000	118,110,000
Charge-offs	(5,136,000)	(3,802,000)	(10,661,000)	(9,074,000)
Recoveries	3,078,000	1,305,000	4,342,000	3,570,000
Provision for loan losses	6,813,000	7,741,000	12,963,000	10,444,000
Ending balance, allowance	129,633,000	123,050,000	129,633,000	123,050,000
Ending balance: individually evaluated for impairment, allowance	14,221,000	10,292,000	14,221,000	10,292,000
Ending balance: collectively evaluated for impairment, allowance	115,412,000	112,758,000	115,412,000	112,758,000
Total loans	10,955,430,000	10,404,527,000	10,955,430,000	10,404,527,000
Ending balance: individually evaluated for impairment, loans	119,805,000	112,491,000	119,805,000	112,491,000
Ending balance: collectively evaluated for impairment, loans	10,835,625,000	10,292,036,000	10,835,625,000	10,292,036,000
Retail [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance, allowance	45,081,000	41,357,000	42,374,000	41,736,000
Charge-offs	(3,180,000)	(3,845,000)	(7,148,000)	(11,757,000)
Recoveries	1,163,000	1,454,000	2,564,000	3,528,000
Provision for loan losses	3,020,000	1,995,000	8,294,000	7,454,000
Ending balance, allowance	46,084,000	40,961,000	46,084,000	40,961,000
Ending balance: individually evaluated for impairment, allowance	1,691,000	1,092,000	1,691,000	1,092,000
Ending balance: collectively evaluated for impairment, allowance	44,393,000	39,869,000	44,393,000	39,869,000
Total loans	4,625,410,000	4,047,868,000	4,625,410,000	4,047,868,000
Ending balance: individually evaluated for impairment, loans	37,788,000	41,013,000	37,788,000	41,013,000
Ending balance: collectively evaluated for impairment, loans	$ 4,587,622,000	$ 4,006,855,000	$ 4,587,622,000	$ 4,006,855,000