Loans and Leases (Summary Of Loan And Lease Portfolio Aging By Class Of Loan) (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	$ 197,366	$ 175,864
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing	934	749
Financing Receivable, Recorded Investment, Nonaccrual Status	163,763	133,816
Financing Receivable, Recorded Investment, Current	17,249,055	16,850,724
Loans and leases	17,446,421	17,026,588	$ 16,623,401
Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	22,019	28,337
Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	10,650	12,962
Residential Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	57,399	58,519
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing	0	0
Financing Receivable, Recorded Investment, Nonaccrual Status	45,676	47,279
Financing Receivable, Recorded Investment, Current	4,442,042	4,196,163
Loans and leases	4,499,441	4,254,682	4,234,047
Residential Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	8,069	8,631
Residential Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	3,654	2,609
Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases	2,566,983	2,684,500	2,707,343
Consumer Portfolio Segment [Member] | Home Equity Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	49,403	50,539
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing	0	0
Financing Receivable, Recorded Investment, Nonaccrual Status	37,105	35,926
Financing Receivable, Recorded Investment, Current	2,269,468	2,359,354
Loans and leases	2,318,871	2,409,893
Consumer Portfolio Segment [Member] | Home Equity Loan [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	7,613	8,831
Consumer Portfolio Segment [Member] | Home Equity Loan [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	4,685	5,782
Consumer Portfolio Segment [Member] | Consumer Borrower [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	5,537	5,381
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing	0	0
Financing Receivable, Recorded Investment, Nonaccrual Status	1,859	1,663
Financing Receivable, Recorded Investment, Current	242,575	269,226
Loans and leases	248,112	274,607
Consumer Portfolio Segment [Member] | Consumer Borrower [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	2,224	2,233
Consumer Portfolio Segment [Member] | Consumer Borrower [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	1,454	1,485
Commercial Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases	5,348,303	4,940,931	4,779,802
Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	62,161	40,898
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing	934	749
Financing Receivable, Recorded Investment, Nonaccrual Status	58,915	38,190
Financing Receivable, Recorded Investment, Current	4,402,543	4,094,727
Loans and leases	4,464,704	4,135,625
Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	1,948	1,382
Commercial Portfolio Segment [Member] | Commercial and Industrial Sector [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	364	577
Commercial Portfolio Segment [Member] | Asset Based Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	8,558	0
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing	0	0
Financing Receivable, Recorded Investment, Nonaccrual Status	8,558	0
Financing Receivable, Recorded Investment, Current	875,041	805,306
Loans and leases	883,599	805,306
Commercial Portfolio Segment [Member] | Asset Based Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Commercial Portfolio Segment [Member] | Asset Based Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans and leases	4,464,917	4,510,846	4,280,513
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	477	662
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing	0	0
Financing Receivable, Recorded Investment, Nonaccrual Status	477	662
Financing Receivable, Recorded Investment, Current	290,474	374,398
Loans and leases	290,951	375,060
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	0	0
Commercial Real Estate Portfolio Segment [Member] | Real Estate Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	12,394	18,044
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing	0	0
Financing Receivable, Recorded Investment, Nonaccrual Status	10,603	9,871
Financing Receivable, Recorded Investment, Current	4,161,572	4,117,742
Loans and leases	4,173,966	4,135,786
Commercial Real Estate Portfolio Segment [Member] | Real Estate Loan [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	1,347	6,357
Commercial Real Estate Portfolio Segment [Member] | Real Estate Loan [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	444	1,816
Finance Leases Portfolio Segment [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	1,437	1,821
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing	0	0
Financing Receivable, Recorded Investment, Nonaccrual Status	570	225
Financing Receivable, Recorded Investment, Current	565,340	633,808
Loans and leases	566,777	635,629	$ 621,696
Finance Leases Portfolio Segment [Member] | Financing Receivables, 30 to 59 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	818	903
Finance Leases Portfolio Segment [Member] | Financing Receivables, 60 to 89 Days Past Due [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Financing Receivable, Recorded Investment, Past Due	$ 49	$ 693