Investment Securities - Reconciliation of Held-to-Maturity Securities (Detail) - USD ($) $ in Thousands	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 941,748		$ 825,137
Gross Unrealized Gains	53		2,046
Gross Unrealized Losses	(132,948)		(11,791)
Allowance for Credit Losses	(190)	$ (199)	(181)	$ (137)	$ 0	$ 0
Fair Value	808,663		815,211
U.S. government agencies
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	16,418		18,672
Gross Unrealized Gains	13		293
Gross Unrealized Losses	(425)		0
Allowance for Credit Losses	0		0
Fair Value	16,006		18,965
Mortgage-backed securities, residential
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	363,071		370,247
Gross Unrealized Gains	23		718
Gross Unrealized Losses	(43,156)		(5,989)
Allowance for Credit Losses	0		0
Fair Value	319,938		364,976
Collateralized mortgage obligations, residential
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	13,773		13,921
Gross Unrealized Gains	0		168
Gross Unrealized Losses	(1,705)		0
Allowance for Credit Losses	0		0
Fair Value	12,068		14,089
Mortgage-backed securities, multifamily
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	5,139		2,710
Gross Unrealized Gains	0		26
Gross Unrealized Losses	(477)		(2)
Allowance for Credit Losses	0		0
Fair Value	4,662		2,734
Obligations of states and political subdivisions
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	540,347		416,587
Gross Unrealized Gains	17		810
Gross Unrealized Losses	(86,962)		(5,800)
Allowance for Credit Losses	(21)		(21)
Fair Value	453,381		411,576
Corporate bonds
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	3,000		3,000
Gross Unrealized Gains	0		31
Gross Unrealized Losses	(223)		0
Allowance for Credit Losses	(169)		(160)
Fair Value	$ 2,608		$ 2,871