Investments - Investment Securities Continuous Unrealized Loss Position (Detail) - USD ($) $ in Thousands	Dec. 31, 2025	Dec. 31, 2024
Marketable Securities [Line Items]
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	$ 642	$ 7,984
Available-for Sale, Gross Unrealized Losses, Total	6,939	12,621
Available-for Sale, Fair value of Investments with Unrealized Losses, Less Than 12 Months	34,429	175,099
Available-for Sale, Gross Unrealized Losses, Less Than 12 Months	642	7,984
Available-for Sale, Fair Value of Investments with Unrealized Losses, 12 Months or Greater	123,699	60,615
Available-for Sale, Gross Unrealized Losses, 12 Months or Greater	6,297	4,637
Available-for Sale, Fair Value of Investments with Unrealized Losses, Total	158,128	235,714
States and Political Subdivisions [Member]
Marketable Securities [Line Items]
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	634	5,748
Available-for Sale, Gross Unrealized Losses, Total	5,482	8,430
Available-for Sale, Fair value of Investments with Unrealized Losses, Less Than 12 Months	28,892	100,190
Available-for Sale, Gross Unrealized Losses, Less Than 12 Months	634	5,748
Available-for Sale, Fair Value of Investments with Unrealized Losses, 12 Months or Greater	76,440	27,446
Available-for Sale, Gross Unrealized Losses, 12 Months or Greater	4,848	2,682
Available-for Sale, Fair Value of Investments with Unrealized Losses, Total	105,332	127,636
Corporate Bonds [Member]
Marketable Securities [Line Items]
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	8	1,790
Available-for Sale, Gross Unrealized Losses, Total	725	2,783
Available-for Sale, Fair value of Investments with Unrealized Losses, Less Than 12 Months	5,537	71,069
Available-for Sale, Gross Unrealized Losses, Less Than 12 Months	8	1,790
Available-for Sale, Fair Value of Investments with Unrealized Losses, 12 Months or Greater	31,115	19,000
Available-for Sale, Gross Unrealized Losses, 12 Months or Greater	717	993
Available-for Sale, Fair Value of Investments with Unrealized Losses, Total	36,652	90,069
U.S. Agency-Based Mortgage-Backed Securities [Member]
Marketable Securities [Line Items]
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		446
Available-for Sale, Gross Unrealized Losses, Total	305	486
Available-for Sale, Fair value of Investments with Unrealized Losses, Less Than 12 Months		3,840
Available-for Sale, Gross Unrealized Losses, Less Than 12 Months		446
Available-for Sale, Fair Value of Investments with Unrealized Losses, 12 Months or Greater	3,641	219
Available-for Sale, Gross Unrealized Losses, 12 Months or Greater	305	40
Available-for Sale, Fair Value of Investments with Unrealized Losses, Total	3,641	4,059
U.S. Treasury Securities and Obligations of U.S. Government Agencies [Member]
Marketable Securities [Line Items]
Debt Securities, Available-for-Sale, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		0
Available-for Sale, Gross Unrealized Losses, Total	427	922
Available-for Sale, Fair value of Investments with Unrealized Losses, Less Than 12 Months		0
Available-for Sale, Gross Unrealized Losses, Less Than 12 Months		0
Available-for Sale, Fair Value of Investments with Unrealized Losses, 12 Months or Greater	12,503	13,950
Available-for Sale, Gross Unrealized Losses, 12 Months or Greater	427	922
Available-for Sale, Fair Value of Investments with Unrealized Losses, Total	$ 12,503	$ 13,950

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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