Loans and Leases (Interest Income From Impaired Loans And Leases, By Class) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	$ 282,917	$ 257,870	$ 253,042
Accrued Interest Income	9,366	8,173	8,313
Cash Basis Interest Income	3,268	2,059	2,086
Consumer Portfolio Segment [Member] | Home Equity Loan [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	41,070	37,167	42,290
Accrued Interest Income	1,315	1,045	1,158
Cash Basis Interest Income	$ 1,826	$ 981	$ 980