Schedule of Amortized Cost and Estimated Fair Value of Company's Fixed Maturities Securities (Detail) - USD ($) $ in Thousands	Jun. 30, 2026	Dec. 31, 2025
Schedule Of Available For Sale Securities [Line Items]
Fixed maturities, Amortized Cost	$ 1,295,106	$ 1,330,310
Fixed maturities, Allowance for Expected Credit Losses	0	0
Fixed maturities, Gross Unrealized Gains	2,980	5,657
Fixed maturities, Gross Unrealized losses	(11,362)	(10,465)
Fixed maturities, Estimated Fair Value	1,286,724	1,325,502
U.S. Treasuries
Schedule Of Available For Sale Securities [Line Items]
Fixed maturities, Amortized Cost	562,521	640,533
Fixed maturities, Allowance for Expected Credit Losses	0	0
Fixed maturities, Gross Unrealized Gains	8	216
Fixed maturities, Gross Unrealized losses	(251)	(120)
Fixed maturities, Estimated Fair Value	562,278	640,629
Obligations of States and Political Subdivisions
Schedule Of Available For Sale Securities [Line Items]
Fixed maturities, Amortized Cost	9,606	14,515
Fixed maturities, Allowance for Expected Credit Losses	0	0
Fixed maturities, Gross Unrealized Gains	0	0
Fixed maturities, Gross Unrealized losses	(347)	(350)
Fixed maturities, Estimated Fair Value	9,259	14,165
Mortgage Backed Securities
Schedule Of Available For Sale Securities [Line Items]
Fixed maturities, Amortized Cost	219,577	199,901
Fixed maturities, Allowance for Expected Credit Losses	0	0
Fixed maturities, Gross Unrealized Gains	1,465	2,610
Fixed maturities, Gross Unrealized losses	(3,893)	(3,451)
Fixed maturities, Estimated Fair Value	217,149	199,060
Asset-backed Securities
Schedule Of Available For Sale Securities [Line Items]
Fixed maturities, Amortized Cost	204,124	139,690
Fixed maturities, Allowance for Expected Credit Losses	0	0
Fixed maturities, Gross Unrealized Gains	687	1,227
Fixed maturities, Gross Unrealized losses	(4,146)	(3,649)
Fixed maturities, Estimated Fair Value	200,665	137,268
Commercial Mortgage-Backed Securities
Schedule Of Available For Sale Securities [Line Items]
Fixed maturities, Amortized Cost	80,311	58,202
Fixed maturities, Allowance for Expected Credit Losses	0	0
Fixed maturities, Gross Unrealized Gains	398	89
Fixed maturities, Gross Unrealized losses	(1,405)	(1,463)
Fixed maturities, Estimated Fair Value	79,304	56,828
Corporate Bonds
Schedule Of Available For Sale Securities [Line Items]
Fixed maturities, Amortized Cost	158,040	198,970
Fixed maturities, Allowance for Expected Credit Losses	0	0
Fixed maturities, Gross Unrealized Gains	288	1,090
Fixed maturities, Gross Unrealized losses	(752)	(867)
Fixed maturities, Estimated Fair Value	157,576	199,193
Foreign Corporate Bonds
Schedule Of Available For Sale Securities [Line Items]
Fixed maturities, Amortized Cost	60,927	78,499
Fixed maturities, Allowance for Expected Credit Losses	0	0
Fixed maturities, Gross Unrealized Gains	134	425
Fixed maturities, Gross Unrealized losses	(568)	(565)
Fixed maturities, Estimated Fair Value	$ 60,493	$ 78,359

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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