Loans and Leases (Summary Of Loan And Lease Portfolio Aging By Class Of Loan) (Detail) - USD ($)	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	$ 200,942,000	$ 193,766,000
90 or More Days Past Due and Accruing	445,000	0
Non-accrual	167,960,000	151,059,000
Current	21,440,273,000	19,843,220,000
Total Loans and Leases	21,641,215,000	20,036,986,000	$ 18,465,489,000
Consumer Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	92,177,000	107,056,000
Non-accrual	72,763,000	74,555,000
Current	6,648,503,000	7,099,753,000
Total Loans and Leases	6,740,680,000	7,206,809,000	6,813,341,000
Consumer Portfolio Segment [Member] | Home Equity Loan [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	38,301,000	43,988,000
Non-accrual	31,030,000	30,170,000
Current	1,764,564,000	1,970,556,000
Total Loans and Leases	1,802,865,000	2,014,544,000
Consumer Portfolio Segment [Member] | Consumer Borrower [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	2,131,000	6,268,000
Non-accrual	652,000	1,192,000
Current	153,668,000	213,312,000
Total Loans and Leases	155,799,000	219,580,000
Consumer Portfolio Segment [Member] | Residential Mortgage [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	51,745,000	56,800,000
Non-accrual	41,081,000	43,193,000
Current	4,730,271,000	4,915,885,000
Total Loans and Leases	4,782,016,000	4,972,685,000
Commercial Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	108,765,000	86,710,000
Non-accrual	95,197,000	76,504,000
Current	14,791,770,000	12,743,467,000
Total Loans and Leases	14,900,535,000	12,830,177,000	$ 11,652,148,000
Commercial Portfolio Segment [Member] | Commercial Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	24,250,000	13,273,000
Non-accrual	21,231,000	11,563,000
Current	6,298,387,000	5,936,066,000
Total Loans and Leases	6,322,637,000	5,949,339,000
Commercial Portfolio Segment [Member] | Non-Real Estate Receivables [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	66,033,000	62,080,000
Non-accrual	64,073,000	59,369,000
Current	7,019,043,000	5,234,531,000
Total Loans and Leases	7,085,076,000	5,296,611,000
Commercial Portfolio Segment [Member] | Asset Based Lending [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	3,768,000	139,000
Non-accrual	2,594,000	139,000
Current	886,830,000	1,046,747,000
Total Loans and Leases	890,598,000	1,046,886,000
Commercial Portfolio Segment [Member] | 6172 Finance Lessors [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	14,714,000	11,218,000
Non-accrual	7,299,000	5,433,000
Current	587,510,000	526,123,000
Total Loans and Leases	602,224,000	537,341,000
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Loans and Leases		5,949,339,000
Finance Leases Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Loans and Leases		537,341,000
Financial Asset, 30 to 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	20,005,000	28,545,000
Financial Asset, 30 to 59 Days Past Due [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	10,712,000	19,702,000
Financial Asset, 30 to 59 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Home Equity Loan [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	5,500,000	8,267,000
Financial Asset, 30 to 59 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Consumer Borrower [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	878,000	4,269,000
Financial Asset, 30 to 59 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Residential Mortgage [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	4,334,000	7,166,000
Financial Asset, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	9,293,000	8,843,000
Financial Asset, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Commercial Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	2,400,000	1,256,000
Financial Asset, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Non-Real Estate Receivables [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	612,000	2,094,000
Financial Asset, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Asset Based Lending [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	1,174,000	0
Financial Asset, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member] | 6172 Finance Lessors [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	5,107,000	5,493,000
Financial Asset, 60 to 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	12,532,000	14,162,000
Financial Asset, 60 to 89 Days Past Due [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	8,702,000	12,799,000
Financial Asset, 60 to 89 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Home Equity Loan [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	1,771,000	5,551,000
Financial Asset, 60 to 89 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Consumer Borrower [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	601,000	807,000
Financial Asset, 60 to 89 Days Past Due [Member] | Consumer Portfolio Segment [Member] | Residential Mortgage [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	6,330,000	6,441,000
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	3,830,000	1,363,000
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Commercial Real Estate [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	619,000	454,000
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Non-Real Estate Receivables [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	903,000	617,000
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Asset Based Lending [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	0	0
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member] | 6172 Finance Lessors [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	2,308,000	292,000
Financial Asset, Equal to or Greater than 90 Days Past Due | Consumer Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
90 or More Days Past Due and Accruing	0	0
Financial Asset, Equal to or Greater than 90 Days Past Due | Consumer Portfolio Segment [Member] | Home Equity Loan [Member]
Financing Receivable, Past Due [Line Items]
90 or More Days Past Due and Accruing	0	0
Financial Asset, Equal to or Greater than 90 Days Past Due | Consumer Portfolio Segment [Member] | Consumer Borrower [Member]
Financing Receivable, Past Due [Line Items]
90 or More Days Past Due and Accruing	0	0
Financial Asset, Equal to or Greater than 90 Days Past Due | Consumer Portfolio Segment [Member] | Residential Mortgage [Member]
Financing Receivable, Past Due [Line Items]
90 or More Days Past Due and Accruing	0	0
Financial Asset, Equal to or Greater than 90 Days Past Due | Commercial Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
90 or More Days Past Due and Accruing	445,000	0
Financial Asset, Equal to or Greater than 90 Days Past Due | Commercial Portfolio Segment [Member] | Commercial Real Estate [Member]
Financing Receivable, Past Due [Line Items]
90 or More Days Past Due and Accruing	0	0
Financial Asset, Equal to or Greater than 90 Days Past Due | Commercial Portfolio Segment [Member] | Non-Real Estate Receivables [Member]
Financing Receivable, Past Due [Line Items]
90 or More Days Past Due and Accruing	445,000	0
Financial Asset, Equal to or Greater than 90 Days Past Due | Commercial Portfolio Segment [Member] | Asset Based Lending [Member]
Financing Receivable, Past Due [Line Items]
90 or More Days Past Due and Accruing	0	0
Financial Asset, Equal to or Greater than 90 Days Past Due | Commercial Portfolio Segment [Member] | 6172 Finance Lessors [Member]
Financing Receivable, Past Due [Line Items]
90 or More Days Past Due and Accruing	$ 0	$ 0