Investment Securities (Debt and Equity Securities Allowance for Credit Losses) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Debt Securities, Held-to-maturity, Allowance for Credit Loss	$ 182	$ 214	$ 299	$ 0
Debt Securities, Held-to-maturity, Allowance for Credit Loss, Recovery	(32)	(85)	(98)
Pledged Financial Instruments, Not Separately Reported, Debt Securities Available-for-sale or Held-for-investment	3,768,173	1,780,164
Pledged Financial Instruments, Not Separately Reported, Debt Securities Held-to-Maturity	1,857,512	3,077,256
Pledged For Municipal Deposits
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Pledged Financial Instruments, Not Separately Reported, Debt Securities Available-for-sale or Held-for-investment	2,573,072	855,323
Pledged Financial Instruments, Not Separately Reported, Debt Securities Held-to-Maturity	1,596,777	1,834,117
Pledged For Borrowings
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Pledged Financial Instruments, Not Separately Reported, Debt Securities Available-for-sale or Held-for-investment	1,195,101	924,841
Pledged Financial Instruments, Not Separately Reported, Debt Securities Held-to-Maturity	$ 260,735	1,243,139
Cumulative Effect, Period of Adoption, Adjustment [Member]
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Debt Securities, Held-to-maturity, Allowance for Credit Loss		$ 0	$ 0	$ 397