Investment Securities - Reconciliation of Held-to-Maturity Securities (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 940,985	$ 825,137
Gross Unrealized Gains	147	2,046
Gross Unrealized Losses	(81,005)	(11,791)
Allowance for Credit Losses	(199)	(181)
Fair Value	859,928	815,211
U.S. government agencies
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	21,795	18,672
Gross Unrealized Gains	52	293
Gross Unrealized Losses	(248)	0
Allowance for Credit Losses	0	0
Fair Value	21,599	18,965
Mortgage-backed securities, residential
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	367,084	370,247
Gross Unrealized Gains	71	718
Gross Unrealized Losses	(27,444)	(5,989)
Allowance for Credit Losses	0	0
Fair Value	339,711	364,976
Collateralized mortgage obligations, residential
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	14,433	13,921
Gross Unrealized Gains	0	168
Gross Unrealized Losses	(1,116)	0
Allowance for Credit Losses	0	0
Fair Value	13,317	14,089
Mortgage-backed securities, multifamily
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	4,270	2,710
Gross Unrealized Gains	0	26
Gross Unrealized Losses	(204)	(2)
Allowance for Credit Losses	0	0
Fair Value	4,066	2,734
Obligations of states and political subdivisions
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	530,403	416,587
Gross Unrealized Gains	24	810
Gross Unrealized Losses	(51,898)	(5,800)
Allowance for Credit Losses	(49)	(21)
Fair Value	478,480	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	(95)	0
Allowance for Credit Losses	(150)	(160)
Fair Value	$ 2,755	$ 2,871