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Loans and Leases (Allowance For Loan And Lease Losses By Portfolio Segment) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	$ 209,096	$ 212,353	$ 199,994
Provision (benefit) charged to expense	137,848	37,800	42,000
Losses charged off	(55,333)	(52,480)	(43,387)
Recoveries	10,252	11,423	13,746
Balance, end of period	209,096	212,353	199,994	$ 359,431	$ 209,096	$ 212,353	$ 199,994
Individually evaluated for impairment				16,137	14,249	15,350
Collectively evaluated for impairment				343,294	194,847	197,003
Individually evaluated for impairment				309,422	256,410	259,330
Collectively evaluated for impairment				21,331,793	19,780,576	18,206,159
Total Loans and Leases				21,641,215	20,036,986	18,465,489
Financing Receivable, Allowance for Credit Loss					209,096
Cumulative Effect, Period of Adoption, Adjustment [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Financing Receivable, Allowance for Credit Loss					57,568	0	0
Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	47,427	48,280	55,248
Provision (benefit) charged to expense	(18,488)	8,626	6,644
Losses charged off	(12,408)	(19,153)	(22,683)
Recoveries	7,112	9,674	9,071
Balance, end of period	47,427	48,280	55,248	47,187	47,427	48,280	55,248
Individually evaluated for impairment				4,450	4,821	5,669
Collectively evaluated for impairment				42,737	42,606	42,611
Individually evaluated for impairment				145,767	125,287	142,675
Collectively evaluated for impairment				6,594,913	7,081,522	6,670,666
Total Loans and Leases				6,740,680	7,206,809	6,813,341
Consumer Portfolio Segment [Member] \| Cumulative Effect, Period of Adoption, Adjustment [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Financing Receivable, Allowance for Credit Loss					23,544	0	0
Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	161,669	164,073	144,746
Provision (benefit) charged to expense	156,336	29,174	35,356
Losses charged off	(42,925)	(33,327)	(20,704)
Recoveries	3,140	1,749	4,675
Balance, end of period	$ 161,669	$ 164,073	$ 144,746	312,244	161,669	164,073	144,746
Individually evaluated for impairment				11,687	9,428	9,681
Collectively evaluated for impairment				300,557	152,241	154,392
Individually evaluated for impairment				163,655	131,123	116,655
Collectively evaluated for impairment				14,736,880	12,699,054	11,535,493
Total Loans and Leases				$ 14,900,535	12,830,177	11,652,148
Commercial Portfolio Segment [Member] \| Cumulative Effect, Period of Adoption, Adjustment [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Financing Receivable, Allowance for Credit Loss					34,024	$ 0	$ 0
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Total Loans and Leases					5,949,339
Finance Leases Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Total Loans and Leases					$ 537,341