Income Taxes (Schedule of Deferred Tax Assets and Liabilities) (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Net unrealized loss on securities available for sale and transferred securities	$ 291,023	$ 349,237
Lease liabilities under operating leases	66,442	67,608
Allowance for credit losses	62,592	60,137
Bonus accrual	9,680	11,204
FDIC deposit insurance special assessment	9,468	0
Stock-based compensation	7,712	6,622
Net actuarial loss on defined benefit post-retirement benefit plans	6,493	9,172
Deferred loan and lease origination fees	4,129	3,675
Other	5,892	6,109
Total gross deferred tax assets	463,431	513,764
Right-of-use assets under operating leases	(58,905)	(60,651)
Premises and equipment	(42,640)	(45,647)
Intangible assets	(18,106)	(17,732)
Defined benefit post-retirement benefit plans	(13,073)	(12,730)
Other	(2,368)	(2,601)
Total gross deferred tax liabilities	(135,092)	(139,361)
Deferred Tax Assets, Net	$ 328,339	$ 374,403