Securities - Summary of Debt Securities with Unrealized Losses, Segregated by Duration of Unrealized Loss (Detail) $ in Thousands	Dec. 31, 2023 USD ($) Investments	Dec. 31, 2022 USD ($) Investments
Debt Securities, Available-for-Sale [Abstract]
Number of investments \| Investments	155	179
Available-for-sale Securities, Less than 12 Months, Fair Value	$ 6,324	$ 818,115
Available-for-sale Securities, Less than 12 Months, Unrealized Losses	97	29,153
Available-for-sale Securities, 12 Months or Longer, Fair Value	1,436,062	698,341
Available-for-sale Securities, 12 Months or Longer, Unrealized Losses	66,004	64,771
Available-for-sale Securities, Fair Value, Total	1,442,386	1,516,456
Available-for-sale Securities, Unrealized Losses, Total	$ 66,101	$ 93,924
U.S. Treasuries [Member]
Debt Securities, Available-for-Sale [Abstract]
Number of investments \| Investments	68	74
Available-for-sale Securities, Less than 12 Months, Fair Value	$ 4,838	$ 787,925
Available-for-sale Securities, Less than 12 Months, Unrealized Losses	90	27,078
Available-for-sale Securities, 12 Months or Longer, Fair Value	1,401,669	689,939
Available-for-sale Securities, 12 Months or Longer, Unrealized Losses	62,545	63,621
Available-for-sale Securities, Fair Value, Total	1,406,507	1,477,864
Available-for-sale Securities, Unrealized Losses, Total	$ 62,635	$ 90,699
U.S. Federal Agencies [Member]
Debt Securities, Available-for-Sale [Abstract]
Number of investments \| Investments	3	1
Available-for-sale Securities, Less than 12 Months, Fair Value	$ 1,100
Available-for-sale Securities, Less than 12 Months, Unrealized Losses	3
Available-for-sale Securities, 12 Months or Longer, Fair Value		$ 349
Available-for-sale Securities, 12 Months or Longer, Unrealized Losses		1
Available-for-sale Securities, Fair Value, Total	1,100	349
Available-for-sale Securities, Unrealized Losses, Total	$ 3	$ 1
Mortgage Backed Securities [Member]
Debt Securities, Available-for-Sale [Abstract]
Number of investments \| Investments	74	92
Available-for-sale Securities, Less than 12 Months, Fair Value	$ 80	$ 10,001
Available-for-sale Securities, Less than 12 Months, Unrealized Losses		1,239
Available-for-sale Securities, 12 Months or Longer, Fair Value	13,261	5,055
Available-for-sale Securities, 12 Months or Longer, Unrealized Losses	1,677	645
Available-for-sale Securities, Fair Value, Total	13,341	15,056
Available-for-sale Securities, Unrealized Losses, Total	$ 1,677	$ 1,884
States and Political Subdivisions [Member]
Debt Securities, Available-for-Sale [Abstract]
Number of investments \| Investments	6	8
Available-for-sale Securities, Less than 12 Months, Fair Value	$ 306	$ 2,308
Available-for-sale Securities, Less than 12 Months, Unrealized Losses	4	184
Available-for-sale Securities, 12 Months or Longer, Fair Value	1,847	464
Available-for-sale Securities, 12 Months or Longer, Unrealized Losses	110	37
Available-for-sale Securities, Fair Value, Total	2,153	2,772
Available-for-sale Securities, Unrealized Losses, Total	$ 114	$ 221
Asset backed Securities [Member]
Debt Securities, Available-for-Sale [Abstract]
Number of investments \| Investments	1	1
Available-for-sale Securities, Less than 12 Months, Fair Value		$ 13,010
Available-for-sale Securities, Less than 12 Months, Unrealized Losses		361
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	13,010
Available-for-sale Securities, Unrealized Losses, Total	$ 282	$ 361
Other Securities [Member]
Debt Securities, Available-for-Sale [Abstract]
Number of investments \| Investments	3	3
Available-for-sale Securities, Less than 12 Months, Fair Value		$ 4,871
Available-for-sale Securities, Less than 12 Months, Unrealized Losses		291
Available-for-sale Securities, 12 Months or Longer, Fair Value	$ 6,773	2,534
Available-for-sale Securities, 12 Months or Longer, Unrealized Losses	1,390	467
Available-for-sale Securities, Fair Value, Total	6,773	7,405
Available-for-sale Securities, Unrealized Losses, Total	$ 1,390	$ 758

No definition available.

Name:	us-gaap_AvailableForSaleSecuritiesAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 55
-Paragraph 8
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479081/326-30-55-8

Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-7

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479106/326-30-50-5

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-7

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479106/326-30-50-5

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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 less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

+ References

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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 less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

+ References

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position without allowance for credit loss.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 55
-Paragraph 8
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479081/326-30-55-8

Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-6

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479106/326-30-50-4

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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 unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-6

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479106/326-30-50-4

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Number of investments in debt securities measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (b)(3)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-6

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (b)(3)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479106/326-30-50-4

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_USTreasurySecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_USGovernmentAgenciesDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_MortgageBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_USStatesAndPoliticalSubdivisionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_AssetBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_OtherDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: