Investment Securities - Reconciliation of Available-for-Sale and Held-to-Maturity Securities in Continuous Unrealized Loss Position (Detail) $ in Thousands	Sep. 30, 2022 USD ($) security	Dec. 31, 2021 USD ($) security
Fair Value
Less Than 12 Months	$ 872,592	$ 378,941
12 Months or Longer	172,569	38,045
Total	$ 1,045,161	$ 416,986
Number of Securities | security	445	94
Unrealized Losses
Less Than 12 Months	$ 78,955	$ 3,508
12 Months or Longer	26,574	923
Total	105,529	4,431
Fair Value
Less Than 12 Months	310,605	650,352
12 Months or Longer	413,892	2,376
Total	724,497	652,728
Unrealized Losses
Less Than 12 Months	63,496	11,684
12 Months or Longer	117,906	107
Total	$ 181,402	$ 11,791
Number of Securities | security	586	336
U.S. government agencies
Fair Value
Less Than 12 Months	$ 303,011	$ 76,106
12 Months or Longer	28,189	14,670
Total	$ 331,200	$ 90,776
Number of Securities | security	66	15
Unrealized Losses
Less Than 12 Months	$ 25,348	$ 322
12 Months or Longer	3,968	467
Total	29,316	789
Fair Value
Less Than 12 Months	14,214
12 Months or Longer	0
Total	14,214
Unrealized Losses
Less Than 12 Months	733
12 Months or Longer	0
Total	$ 733
Number of Securities | security	4
Mortgage-backed securities, residential
Fair Value
Less Than 12 Months	$ 254,502	176,990
12 Months or Longer	58,564	14,582
Total	$ 313,066	$ 191,572
Number of Securities | security	136	45
Unrealized Losses
Less Than 12 Months	$ 34,557	$ 1,465
12 Months or Longer	11,293	266
Total	45,850	1,731
Fair Value
Less Than 12 Months	80,909	340,474
12 Months or Longer	214,223	2,376
Total	295,132	342,850
Unrealized Losses
Less Than 12 Months	12,964	5,882
12 Months or Longer	49,006	107
Total	$ 61,970	$ 5,989
Number of Securities | security	182	96
Collateralized mortgage obligations, residential
Fair Value
Less Than 12 Months	$ 100,681	$ 86,749
12 Months or Longer	60,543	5,000
Total	$ 161,224	$ 91,749
Number of Securities | security	107	18
Unrealized Losses
Less Than 12 Months	$ 7,502	$ 1,429
12 Months or Longer	8,306	59
Total	15,808	1,488
Fair Value
Less Than 12 Months	10,947
12 Months or Longer	0
Total	10,947
Unrealized Losses
Less Than 12 Months	2,380
12 Months or Longer	0
Total	$ 2,380
Number of Securities | security	12
Mortgage-backed securities, multifamily
Fair Value
Less Than 12 Months	$ 0	0
12 Months or Longer	785	1,741
Total	$ 785	$ 1,741
Number of Securities | security	1	1
Unrealized Losses
Less Than 12 Months	$ 0	$ 0
12 Months or Longer	221	75
Total	221	75
Fair Value
Less Than 12 Months	4,349
12 Months or Longer	0
Total	4,349
Unrealized Losses
Less Than 12 Months	768
12 Months or Longer	0
Total	$ 768
Number of Securities | security	4
Collateralized mortgage obligations, multifamily
Fair Value
Less Than 12 Months	$ 40,474	9,083
12 Months or Longer	6,249	1,072
Total	$ 46,723	$ 10,155
Number of Securities | security	20	4
Unrealized Losses
Less Than 12 Months	$ 3,270	$ 210
12 Months or Longer	1,717	36
Total	4,987	246
Fair Value
Less Than 12 Months		2,051
12 Months or Longer		0
Total		2,051
Unrealized Losses
Less Than 12 Months		2
12 Months or Longer		0
Total		$ 2
Number of Securities | security		1
Asset-backed securities
Fair Value
Less Than 12 Months	44,227	$ 14,688
12 Months or Longer	13,317	0
Total	$ 57,544	$ 14,688
Number of Securities | security	18	3
Unrealized Losses
Less Than 12 Months	$ 1,049	$ 87
12 Months or Longer	539	0
Total	1,588	87
Obligations of states and political subdivisions
Fair Value
Less Than 12 Months	20,594
12 Months or Longer	0
Total	$ 20,594
Number of Securities | security	47
Unrealized Losses
Less Than 12 Months	$ 1,504
12 Months or Longer	0
Total	1,504
Fair Value
Less Than 12 Months	197,570	307,827
12 Months or Longer	199,669	0
Total	397,239	307,827
Unrealized Losses
Less Than 12 Months	46,268	5,800
12 Months or Longer	68,900	0
Total	$ 115,168	$ 5,800
Number of Securities | security	383	239
Corporate bonds
Fair Value
Less Than 12 Months	$ 109,103	$ 15,325
12 Months or Longer	4,922	980
Total	$ 114,025	$ 16,305
Number of Securities | security	50	8
Unrealized Losses
Less Than 12 Months	$ 5,725	$ (5)
12 Months or Longer	530	20
Total	6,255	$ 15
Fair Value
Less Than 12 Months	2,616
12 Months or Longer	0
Total	2,616
Unrealized Losses
Less Than 12 Months	383
12 Months or Longer	0
Total	$ 383
Number of Securities | security	1