Loans and Leases (Summary Of Loan And Lease Portfolio Aging By Class Of Loan) (Detail) - USD ($)	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	$ 199,498,000	$ 193,766,000
Financing Receivable, Nonaccrual	162,430,000	151,059,000	$ 151,059,000
Financing Receivable, 90 Days or More Past Due, Still Accruing	75,000	0
Financing Receivable, Not Past Due	20,692,026,000	19,843,220,000
Loans and leases	20,891,524,000	20,036,986,000	18,814,290,000
Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	26,510,000	28,545,000
Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	10,483,000	14,162,000
Commercial Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Nonaccrual	87,136,000		76,504,000
Loans and leases	13,688,421,000	12,830,177,000	11,842,767,000
Commercial Portfolio Segment [Member] \| Commercial and Industrial Sector [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	69,032,000	62,080,000
Financing Receivable, Nonaccrual	65,139,000	59,369,000	59,369,000
Financing Receivable, Not Past Due	5,769,641,000	5,234,531,000
Loans and leases	5,838,673,000	5,296,611,000
Commercial Portfolio Segment [Member] \| Commercial and Industrial Sector [Member] \| Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	3,303,000	2,094,000
Commercial Portfolio Segment [Member] \| Commercial and Industrial Sector [Member] \| Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	515,000	617,000
Financing Receivable, 90 Days or More Past Due, Still Accruing	75,000	0
Commercial Portfolio Segment [Member] \| Asset Based Lending
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	137,000	139,000
Financing Receivable, Nonaccrual	137,000	139,000	139,000
Financing Receivable, Not Past Due	1,180,191,000	1,046,747,000
Loans and leases	1,180,328,000	1,046,886,000
Commercial Portfolio Segment [Member] \| Asset Based Lending \| Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	0	0
Commercial Portfolio Segment [Member] \| Asset Based Lending \| Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	0	0
Financing Receivable, 90 Days or More Past Due, Still Accruing	0	0
Commercial Portfolio Segment [Member] \| Commercial Real Estate
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	15,132,000	13,273,000
Financing Receivable, Nonaccrual	12,910,000	11,563,000	11,563,000
Financing Receivable, Not Past Due	6,107,342,000	5,936,066,000
Loans and leases	6,122,474,000	5,949,339,000
Commercial Portfolio Segment [Member] \| Commercial Real Estate \| Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	2,222,000	1,256,000
Commercial Portfolio Segment [Member] \| Commercial Real Estate \| Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	0	454,000
Financing Receivable, 90 Days or More Past Due, Still Accruing	0	0
Commercial Portfolio Segment [Member] \| 6172 Finance Lessors
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	13,355,000	11,218,000
Financing Receivable, Nonaccrual	8,950,000	5,433,000	5,433,000
Financing Receivable, Not Past Due	533,591,000	526,123,000
Loans and leases	546,946,000	537,341,000
Commercial Portfolio Segment [Member] \| 6172 Finance Lessors \| Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	3,922,000	5,493,000
Commercial Portfolio Segment [Member] \| 6172 Finance Lessors \| Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	483,000	292,000
Financing Receivable, 90 Days or More Past Due, Still Accruing	0	0
Consumer Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Nonaccrual	75,294,000		74,555,000
Loans and leases	7,203,103,000	7,206,809,000	6,971,523,000
Consumer Portfolio Segment [Member] \| Residential Mortgage [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	54,300,000	56,800,000
Financing Receivable, Nonaccrual	42,465,000	43,193,000	43,193,000
Financing Receivable, Not Past Due	4,937,212,000	4,915,885,000
Loans and leases	4,991,512,000	4,972,685,000
Consumer Portfolio Segment [Member] \| Residential Mortgage [Member] \| Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	7,603,000	7,166,000
Consumer Portfolio Segment [Member] \| Residential Mortgage [Member] \| Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	4,232,000	6,441,000
Financing Receivable, 90 Days or More Past Due, Still Accruing	0	0
Consumer Portfolio Segment [Member] \| Home Equity Loan [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	44,488,000	43,988,000
Financing Receivable, Nonaccrual	31,796,000	30,170,000	$ 30,170,000
Financing Receivable, Not Past Due	1,947,884,000	1,970,556,000
Loans and leases	1,992,372,000	2,014,544,000
Consumer Portfolio Segment [Member] \| Home Equity Loan [Member] \| Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	8,230,000	8,267,000
Consumer Portfolio Segment [Member] \| Home Equity Loan [Member] \| Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	4,462,000	5,551,000
Financing Receivable, 90 Days or More Past Due, Still Accruing	0	0
Consumer Portfolio Segment [Member] \| Consumer Borrower [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	3,054,000	6,268,000
Financing Receivable, Nonaccrual	1,033,000	1,192,000
Financing Receivable, Not Past Due	216,165,000	213,312,000
Loans and leases	219,219,000	219,580,000
Consumer Portfolio Segment [Member] \| Consumer Borrower [Member] \| Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	1,230,000	4,269,000
Consumer Portfolio Segment [Member] \| Consumer Borrower [Member] \| Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Past Due	791,000	807,000
Financing Receivable, 90 Days or More Past Due, Still Accruing	$ 0	$ 0

Amount of financing receivable 90 days or more past due and still accruing.

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