Securities - Summary of Debt Securities with Unrealized Losses, Segregated by Duration of Unrealized Loss (Detail) $ in Thousands	Jun. 30, 2025 USD ($) Investments	Dec. 31, 2024 USD ($) Investments
Debt Securities, Available-for-Sale [Abstract]
Number of investments \| Investments	109	126
Available-for-sale Securities, Less than 12 Months, Fair Value	$ 2,601	$ 92,564
Available-for-sale Securities, Less than 12 Months, Unrealized Losses	6	1,051
Available-for-sale Securities, 12 Months or Longer, Fair Value	999,309	1,106,088
Available-for-sale Securities, 12 Months or Longer, Unrealized Losses	23,783	42,083
Available-for-sale Securities, Fair Value, Total	1,001,910	1,198,652
Available-for-sale Securities, Unrealized Losses, Total	$ 23,789	$ 43,134
U.S. Treasuries [Member]
Debt Securities, Available-for-Sale [Abstract]
Number of investments \| Investments	42	51
Available-for-sale Securities, Less than 12 Months, Fair Value	$ 0	$ 89,867
Available-for-sale Securities, Less than 12 Months, Unrealized Losses	0	1,030
Available-for-sale Securities, 12 Months or Longer, Fair Value	979,845	1,086,142
Available-for-sale Securities, 12 Months or Longer, Unrealized Losses	21,223	39,219
Available-for-sale Securities, Fair Value, Total	979,845	1,176,009
Available-for-sale Securities, Unrealized Losses, Total	$ 21,223	$ 40,249
U.S. Federal Agencies [Member]
Debt Securities, Available-for-Sale [Abstract]
Number of investments \| Investments	5	5
Available-for-sale Securities, Less than 12 Months, Fair Value	$ 637	$ 681
Available-for-sale Securities, Less than 12 Months, Unrealized Losses	3	4
Available-for-sale Securities, 12 Months or Longer, Fair Value	440	500
Available-for-sale Securities, 12 Months or Longer, Unrealized Losses	2	2
Available-for-sale Securities, Fair Value, Total	1,077	1,181
Available-for-sale Securities, Unrealized Losses, Total	$ 5	$ 6
Mortgage Backed Securities [Member]
Debt Securities, Available-for-Sale [Abstract]
Number of investments \| Investments	55	63
Available-for-sale Securities, Less than 12 Months, Fair Value	$ 1,163	$ 1,214
Available-for-sale Securities, Less than 12 Months, Unrealized Losses	2	15
Available-for-sale Securities, 12 Months or Longer, Fair Value	11,068	11,498
Available-for-sale Securities, 12 Months or Longer, Unrealized Losses	1,467	1,757
Available-for-sale Securities, Fair Value, Total	12,231	12,712
Available-for-sale Securities, Unrealized Losses, Total	$ 1,469	$ 1,772
States and Political Subdivisions [Member]
Debt Securities, Available-for-Sale [Abstract]
Number of investments \| Investments	4	4
Available-for-sale Securities, Less than 12 Months, Fair Value	$ 801	$ 802
Available-for-sale Securities, Less than 12 Months, Unrealized Losses	1	2
Available-for-sale Securities, 12 Months or Longer, Fair Value	758	752
Available-for-sale Securities, 12 Months or Longer, Unrealized Losses	126	138
Available-for-sale Securities, Fair Value, Total	1,559	1,554
Available-for-sale Securities, Unrealized Losses, Total	$ 127	$ 140
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	$ 7,198	$ 7,196
Available-for-sale Securities, 12 Months or Longer, Unrealized Losses	965	967
Available-for-sale Securities, Fair Value, Total	7,198	7,196
Available-for-sale Securities, Unrealized Losses, Total	$ 965	$ 967

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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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