Investment Securities - Reconciliation of Held-to-Maturity Securities (Detail) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022	Dec. 31, 2021
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 902,655	$ 923,415
Gross Unrealized Gains	137	70
Gross Unrealized Losses	(139,915)	(162,923)
Allowance for Credit Losses	(157)	(107)	$ (199)	$ (181)
Fair Value	762,720	760,455
U.S. government agencies
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	10,968	11,099
Gross Unrealized Gains	10	11
Gross Unrealized Losses	(622)	(725)
Allowance for Credit Losses	0	0
Fair Value	10,356	10,385
Mortgage-backed securities, residential
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	354,514	360,683
Gross Unrealized Gains	123	57
Gross Unrealized Losses	(52,843)	(58,128)
Allowance for Credit Losses	0	0
Fair Value	301,794	302,612
Collateralized mortgage obligations, residential
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	12,813	13,026
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(2,325)	(2,570)
Allowance for Credit Losses	0	0
Fair Value	10,488	10,456
Mortgage-backed securities, multifamily
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	5,071	5,094
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(665)	(747)
Allowance for Credit Losses	0	0
Fair Value	4,406	4,347
Obligations of states and political subdivisions
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	516,289	530,513
Gross Unrealized Gains	4	2
Gross Unrealized Losses	(83,042)	(100,400)
Allowance for Credit Losses	(45)	(7)
Fair Value	433,206	430,108
Corporate bonds
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	3,000	3,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(418)	(353)
Allowance for Credit Losses	(112)	(100)
Fair Value	$ 2,470	$ 2,547