Securities - Summary of Debt Securities with Unrealized Losses, Segregated by Duration of Unrealized Loss (Detail) $ in Thousands	Jun. 30, 2024 USD ($) Investments	Dec. 31, 2023 USD ($) Investments
Debt Securities, Available-for-Sale [Abstract]
Number of investments \| Investments	144	155
Available-for-sale Securities, Less than 12 Months, Fair Value	$ 92,344	$ 6,324
Available-for-sale Securities, Less than 12 Months, Unrealized Losses	940	97
Available-for-sale Securities, 12 Months or Longer, Fair Value	1,322,533	1,436,062
Available-for-sale Securities, 12 Months or Longer, Unrealized Losses	62,418	66,004
Available-for-sale Securities, Fair Value, Total	1,414,877	1,442,386
Available-for-sale Securities, Unrealized Losses, Total	$ 63,358	$ 66,101
U.S. Treasuries [Member]
Debt Securities, Available-for-Sale [Abstract]
Number of investments \| Investments	62	68
Available-for-sale Securities, Less than 12 Months, Fair Value	$ 90,084	$ 4,838
Available-for-sale Securities, Less than 12 Months, Unrealized Losses	926	90
Available-for-sale Securities, 12 Months or Longer, Fair Value	1,300,697	1,401,669
Available-for-sale Securities, 12 Months or Longer, Unrealized Losses	59,207	62,545
Available-for-sale Securities, Fair Value, Total	1,390,781	1,406,507
Available-for-sale Securities, Unrealized Losses, Total	$ 60,133	$ 62,635
U.S. Federal Agencies [Member]
Debt Securities, Available-for-Sale [Abstract]
Number of investments \| Investments	2	3
Available-for-sale Securities, Less than 12 Months, Fair Value	$ 205	$ 1,100
Available-for-sale Securities, Less than 12 Months, Unrealized Losses	2	3
Available-for-sale Securities, 12 Months or Longer, Fair Value	688
Available-for-sale Securities, 12 Months or Longer, Unrealized Losses	1
Available-for-sale Securities, Fair Value, Total	893	1,100
Available-for-sale Securities, Unrealized Losses, Total	$ 3	$ 3
Mortgage Backed Securities [Member]
Debt Securities, Available-for-Sale [Abstract]
Number of investments \| Investments	69	74
Available-for-sale Securities, Less than 12 Months, Fair Value	$ 1,188	$ 80
Available-for-sale Securities, Less than 12 Months, Unrealized Losses	9
Available-for-sale Securities, 12 Months or Longer, Fair Value	12,455	13,261
Available-for-sale Securities, 12 Months or Longer, Unrealized Losses	1,737	1,677
Available-for-sale Securities, Fair Value, Total	13,643	13,341
Available-for-sale Securities, Unrealized Losses, Total	$ 1,746	$ 1,677
States and Political Subdivisions [Member]
Debt Securities, Available-for-Sale [Abstract]
Number of investments \| Investments	8	6
Available-for-sale Securities, Less than 12 Months, Fair Value	$ 867	$ 306
Available-for-sale Securities, Less than 12 Months, Unrealized Losses	3	4
Available-for-sale Securities, 12 Months or Longer, Fair Value	1,871	1,847
Available-for-sale Securities, 12 Months or Longer, Unrealized Losses	132	110
Available-for-sale Securities, Fair Value, Total	2,738	2,153
Available-for-sale Securities, Unrealized Losses, Total	$ 135	$ 114
Asset backed Securities [Member]
Debt Securities, Available-for-Sale [Abstract]
Number of investments \| Investments		1
Available-for-sale Securities, 12 Months or Longer, Fair Value		$ 12,512
Available-for-sale Securities, 12 Months or Longer, Unrealized Losses		282
Available-for-sale Securities, Fair Value, Total		12,512
Available-for-sale Securities, Unrealized Losses, Total		$ 282
Other Securities [Member]
Debt Securities, Available-for-Sale [Abstract]
Number of investments \| Investments	3	3
Available-for-sale Securities, 12 Months or Longer, Fair Value	$ 6,822	$ 6,773
Available-for-sale Securities, 12 Months or Longer, Unrealized Losses	1,341	1,390
Available-for-sale Securities, Fair Value, Total	6,822	6,773
Available-for-sale Securities, Unrealized Losses, Total	$ 1,341	$ 1,390

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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