Investment Securities - Reconciliation of Available-for-Sale and Held-to-Maturity Securities in Continuous Unrealized Loss Position (Detail) $ in Thousands	Mar. 31, 2024 USD ($) security	Dec. 31, 2023 USD ($) security
Fair Value
Less Than 12 Months	$ 7,547	$ 5,561
12 Months or Longer	884,612	927,745
Total	$ 892,159	$ 933,306
Number of Securities | security	404	407
Unrealized Losses
Less Than 12 Months	$ 14	$ 25
12 Months or Longer	90,403	89,046
Total	90,417	89,071
Fair Value
Less Than 12 Months	9,401	3,976
12 Months or Longer	658,251	679,756
Total	667,652	683,732
Unrealized Losses
Less Than 12 Months	24	4
12 Months or Longer	145,262	133,942
Total	$ 145,286	$ 133,946
Number of Securities | security	538	542
U.S. government agencies
Fair Value
Less Than 12 Months	$ 3,515	$ 2,587
12 Months or Longer	290,930	308,315
Total	$ 294,445	$ 310,902
Number of Securities | security	57	59
Unrealized Losses
Less Than 12 Months	$ 7	$ 0
12 Months or Longer	19,563	19,694
Total	19,570	19,694
Fair Value
Less Than 12 Months	0	0
12 Months or Longer	8,913	8,956
Total	8,913	8,956
Unrealized Losses
Less Than 12 Months	0	0
12 Months or Longer	499	499
Total	$ 499	$ 499
Number of Securities | security	3	3
Mortgage-backed securities, residential
Fair Value
Less Than 12 Months	$ 212	$ 10
12 Months or Longer	276,555	284,803
Total	$ 276,767	$ 284,813
Number of Securities | security	130	129
Unrealized Losses
Less Than 12 Months	$ 1	$ 0
12 Months or Longer	36,345	34,546
Total	36,346	34,546
Fair Value
Less Than 12 Months	5,208	285
12 Months or Longer	263,239	274,528
Total	268,447	274,813
Unrealized Losses
Less Than 12 Months	8	2
12 Months or Longer	57,881	52,163
Total	$ 57,889	$ 52,165
Number of Securities | security	184	183
Collateralized mortgage obligations, residential
Fair Value
Less Than 12 Months	$ 0	$ 0
12 Months or Longer	132,206	137,070
Total	$ 132,206	$ 137,070
Number of Securities | security	100	100
Unrealized Losses
Less Than 12 Months	$ 0	$ 0
12 Months or Longer	13,874	13,656
Total	13,874	13,656
Fair Value
Less Than 12 Months	0	0
12 Months or Longer	9,201	9,447
Total	9,201	9,447
Unrealized Losses
Less Than 12 Months	0	0
12 Months or Longer	2,878	2,796
Total	$ 2,878	$ 2,796
Number of Securities | security	10	11
Mortgage-backed securities, multifamily
Fair Value
Less Than 12 Months	$ 0	$ 0
12 Months or Longer	667	676
Total	$ 667	$ 676
Number of Securities | security	1	1
Unrealized Losses
Less Than 12 Months	$ 0	$ 0
12 Months or Longer	184	180
Total	184	180
Fair Value
Less Than 12 Months	0	0
12 Months or Longer	3,449	3,494
Total	3,449	3,494
Unrealized Losses
Less Than 12 Months	0	0
12 Months or Longer	677	651
Total	$ 677	$ 651
Number of Securities | security	3	3
Collateralized mortgage obligations, multifamily
Fair Value
Less Than 12 Months	$ 0	$ 0
12 Months or Longer	41,773	42,496
Total	$ 41,773	$ 42,496
Number of Securities | security	18	20
Unrealized Losses
Less Than 12 Months	$ 0	$ 0
12 Months or Longer	4,033	4,045
Total	4,033	4,045
Asset-backed securities
Fair Value
Less Than 12 Months	1,532	2,694
12 Months or Longer	32,814	40,999
Total	$ 34,346	$ 43,693
Number of Securities | security	14	16
Unrealized Losses
Less Than 12 Months	$ 0	$ 25
12 Months or Longer	412	843
Total	412	868
Obligations of states and political subdivisions
Fair Value
Less Than 12 Months	2,288	270
12 Months or Longer	15,570	16,353
Total	$ 17,858	$ 16,623
Number of Securities | security	39	36
Unrealized Losses
Less Than 12 Months	$ 6	$ 0
12 Months or Longer	599	571
Total	605	571
Fair Value
Less Than 12 Months	4,193	3,691
12 Months or Longer	371,272	380,787
Total	375,465	384,478
Unrealized Losses
Less Than 12 Months	16	2
12 Months or Longer	82,504	77,377
Total	$ 82,520	$ 77,379
Number of Securities | security	337	341
Corporate bonds
Fair Value
Less Than 12 Months	$ 0	$ 0
12 Months or Longer	94,097	97,033
Total	$ 94,097	$ 97,033
Number of Securities | security	45	46
Unrealized Losses
Less Than 12 Months	$ 0	$ 0
12 Months or Longer	15,393	15,511
Total	15,393	15,511
Fair Value
Less Than 12 Months	0	0
12 Months or Longer	2,177	2,544
Total	2,177	2,544
Unrealized Losses
Less Than 12 Months	0	0
12 Months or Longer	823	456
Total	$ 823	$ 456
Number of Securities | security	1	1