Loans and Leases (Summary Of The Recorded Investment Of Company's TDRs) (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total recorded investment of TDR	$ 237,438	$ 230,414
Specific reserves for TDR included in the balance of ALLL	209,096	212,353	$ 199,994	$ 194,320
Additional funds committed to borrowers in TDR status	4,856	3,893
Performing Financial Instruments [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total recorded investment of TDR	136,449	138,479
Nonperforming Financial Instruments [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Total recorded investment of TDR	100,989	91,935
Troubled Debt Restructures [Member] | Nonperforming Financial Instruments [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Specific reserves for TDR included in the balance of ALLL	$ 12,956	$ 11,930