Loans and Leases (Allowance For Loan And Lease Losses By Portfolio Segment) (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2017
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period				$ 212,353				$ 199,994	$ 212,353	$ 199,994	$ 194,320
Provision (benefit) charged to expense	$ 6,000	$ 11,300	$ 11,900	8,600	$ 10,000	$ 10,500	$ 10,500	11,000	37,800	42,000	40,900
Losses charged off									(52,480)	(43,387)	(44,927)
Recoveries									11,423	13,746	9,701
Balance, end of period	209,096			212,353	212,353			199,994	212,353	199,994	194,320	$ 199,994
Individually evaluated for impairment	14,249				15,350							16,554
Collectively evaluated for impairment	194,847				197,003							183,440
Individually evaluated for impairment	256,410				259,330							246,753
Collectively evaluated for impairment	19,780,576				18,206,159							17,277,105
Total Loans and Leases	20,036,986				18,465,489							17,523,858
Residential Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period				19,599				19,058	19,599	19,058	23,226
Provision (benefit) charged to expense									4,110	2,016	(2,692)
Losses charged off									(4,153)	(3,455)	(2,500)
Recoveries									1,363	1,980	1,024
Balance, end of period	20,919			19,599	19,599			19,058	19,599	19,058	23,226	19,058
Individually evaluated for impairment	3,618				4,286							4,805
Collectively evaluated for impairment	17,301				15,313							14,253
Individually evaluated for impairment	90,096				103,531							114,295
Collectively evaluated for impairment	4,882,589				4,313,106							4,376,583
Total Loans and Leases	4,972,685				4,416,637							4,490,878
Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period				28,681				36,190	28,681	36,190	45,233
Provision (benefit) charged to expense									4,516	4,628	9,367
Losses charged off									(15,000)	(19,228)	(24,447)
Recoveries									8,311	7,091	6,037
Balance, end of period	26,508			28,681	28,681			36,190	28,681	36,190	45,233	36,190
Individually evaluated for impairment	1,203				1,383							1,668
Collectively evaluated for impairment	25,305				27,298							34,522
Individually evaluated for impairment	35,191				39,144							45,436
Collectively evaluated for impairment	2,198,933				2,357,560							2,544,789
Total Loans and Leases	2,234,124				2,396,704							2,590,225
Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period				98,793				89,533	98,793	89,533	71,905
Provision (benefit) charged to expense									20,370	23,041	23,417
Losses charged off									(29,033)	(18,220)	(8,147)
Recoveries									1,626	4,439	2,358
Balance, end of period	91,756			98,793	98,793			89,533	98,793	89,533	71,905	89,533
Individually evaluated for impairment	7,867				7,824							9,786
Collectively evaluated for impairment	83,889				90,969							79,747
Individually evaluated for impairment	102,393				99,512							72,471
Collectively evaluated for impairment	6,241,104				6,117,094							5,296,223
Total Loans and Leases	6,343,497				6,216,606							5,368,694
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period				60,151				49,407	60,151	49,407	47,477
Provision (benefit) charged to expense									8,550	12,644	11,040
Losses charged off									(3,501)	(2,061)	(9,275)
Recoveries									45	161	165
Balance, end of period	65,245			60,151	60,151			49,407	60,151	49,407	47,477	49,407
Individually evaluated for impairment	1,143				1,661							272
Collectively evaluated for impairment	64,102				58,490							49,135
Individually evaluated for impairment	23,297				10,828							11,226
Collectively evaluated for impairment	5,926,042				4,916,317							4,512,602
Total Loans and Leases	5,949,339				4,927,145							4,523,828
Finance Leases Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period				5,129				5,806	5,129	5,806	6,479
Provision (benefit) charged to expense									254	(329)	(232)
Losses charged off									(793)	(423)	(558)
Recoveries									78	75	117
Balance, end of period	4,668			$ 5,129	5,129			$ 5,806	$ 5,129	$ 5,806	$ 6,479	5,806
Individually evaluated for impairment	418				196							23
Collectively evaluated for impairment	4,250				4,933							5,783
Individually evaluated for impairment	5,433				6,315							3,325
Collectively evaluated for impairment	531,908				502,082							546,908
Total Loans and Leases	$ 537,341				$ 508,397							$ 550,233