Income Taxes (Schedule of Deferred Tax Assets and Liabilities) (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Lease liabilities under operating leases	$ 67,975	$ 0
Allowance for loan losses	27,755	27,748
Net actuarial loss on defined benefit post-retirement benefit plans	12,210	12,626
Stock-based compensation	11,211	10,622
Bonus accrual	5,055	4,586
Net unrealized loss on securities available for sale and transferred securities	0	4,283
Deferred loan and lease origination fees	2,254	2,153
Other	2,163	4,761
Total gross deferred tax assets	128,623	66,779
Net unrealized gain on securities available for sale and transferred securities	(83,281)	0
Right-of-use assets under operating leases	(63,463)	0
Premises and equipment	(29,730)	(23,859)
Intangible assets	(12,642)	(10,726)
Defined benefit post-retirement benefit plans	(9,419)	(9,452)
Partnership interests	(2,894)	0
Leases	(1,572)	(1,709)
Other	(1,440)	(1,257)
Total gross deferred tax liabilities	(204,441)	(47,003)
Deferred Tax Liabilities, Net	$ (75,818)
Deferred Tax Assets, Net		$ 19,776