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		12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Allowance for loan losses:
Beginning balance, allowance	$ 253,514,000	$ 254,516,000	$ 251,758,000	$ 252,496,000	$ 252,496,000
Charge-offs	(19,663,000)	(15,771,000)	(32,398,000)	(27,086,000)
Recoveries	3,984,000	9,638,000	9,801,000	13,596,000
Provision for loan losses	10,260,000	6,693,000	18,934,000	16,070,000
Ending balance, allowance	248,095,000	255,076,000	248,095,000	255,076,000	251,758,000
Ending balance: individually evaluated for impairment, allowance	12,650,000	28,427,000	12,650,000	28,427,000
Ending balance: collectively evaluated for impairment, allowance	235,445,000	226,649,000	235,445,000	226,649,000
Ending balance: total loans	24,456,550,000	23,088,535,000	24,456,550,000	23,088,535,000	23,882,382,000
Ending balance: individually evaluated for impairment, loans	228,215,000	270,547,000	228,215,000	270,547,000
Ending balance: collectively evaluated for impairment, loans	24,228,335,000	22,817,988,000	24,228,335,000	22,817,988,000
Purchased credit-impaired loans	0	0	0	0
Allowance for purchased credit-impaired loans	0	0	0	0
Deferred fees and costs, net	26,000,000	27,600,000	26,000,000	27,600,000	26,000,000
Commercial Real Estate
Allowance for loan losses:
Beginning balance, allowance	78,314,000	84,557,000	81,816,000	87,133,000	87,133,000
Charge-offs	(1,299,000)	(7,455,000)	(3,207,000)	(9,277,000)
Recoveries	759,000	5,397,000	3,648,000	6,690,000
Provision for loan losses	(247,000)	(3,140,000)	(4,730,000)	(5,187,000)
Ending balance, allowance	77,527,000	79,359,000	77,527,000	79,359,000	81,816,000
Ending balance: individually evaluated for impairment, allowance	4,386,000	12,515,000	4,386,000	12,515,000
Ending balance: collectively evaluated for impairment, allowance	73,141,000	66,844,000	73,141,000	66,844,000
Ending balance: total loans	7,414,271,000	7,507,695,000	7,414,271,000	7,507,695,000
Ending balance: individually evaluated for impairment, loans	73,638,000	112,954,000	73,638,000	112,954,000
Ending balance: collectively evaluated for impairment, loans	7,340,633,000	7,394,741,000	7,340,633,000	7,394,741,000
Commercial & Industrial
Allowance for loan losses:
Beginning balance, allowance	127,096,000	124,878,000	125,778,000	122,989,000	122,989,000
Charge-offs	(12,642,000)	(5,136,000)	(19,535,000)	(10,661,000)
Recoveries	1,458,000	3,078,000	3,282,000	4,342,000
Provision for loan losses	7,525,000	6,813,000	13,912,000	12,963,000
Ending balance, allowance	123,437,000	129,633,000	123,437,000	129,633,000	125,778,000
Ending balance: individually evaluated for impairment, allowance	7,226,000	14,221,000	7,226,000	14,221,000
Ending balance: collectively evaluated for impairment, allowance	116,211,000	115,412,000	116,211,000	115,412,000
Ending balance: total loans	11,750,908,000	10,955,430,000	11,750,908,000	10,955,430,000
Ending balance: individually evaluated for impairment, loans	122,889,000	119,805,000	122,889,000	119,805,000
Ending balance: collectively evaluated for impairment, loans	11,628,019,000	10,835,625,000	11,628,019,000	10,835,625,000
Retail
Allowance for loan losses:
Beginning balance, allowance	48,104,000	45,081,000	44,164,000	42,374,000	42,374,000
Charge-offs	(5,722,000)	(3,180,000)	(9,656,000)	(7,148,000)
Recoveries	1,767,000	1,163,000	2,871,000	2,564,000
Provision for loan losses	2,982,000	3,020,000	9,752,000	8,294,000
Ending balance, allowance	47,131,000	46,084,000	47,131,000	46,084,000	$ 44,164,000
Ending balance: individually evaluated for impairment, allowance	1,038,000	1,691,000	1,038,000	1,691,000
Ending balance: collectively evaluated for impairment, allowance	46,093,000	44,393,000	46,093,000	44,393,000
Ending balance: total loans	5,291,371,000	4,625,410,000	5,291,371,000	4,625,410,000
Ending balance: individually evaluated for impairment, loans	31,688,000	37,788,000	31,688,000	37,788,000
Ending balance: collectively evaluated for impairment, loans	$ 5,259,683,000	$ 4,587,622,000	$ 5,259,683,000	$ 4,587,622,000