Fair Value of Financial Instruments Additional Information (Detail) - USD ($) $ in Millions	Sep. 30, 2026	Dec. 31, 2025
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Ceded Policy Loans	$ 3,216.4	$ 3,353.8
Derivative Credit Risk Valuation Adjustment, Derivative Assets	0.0	0.0
Derivative Credit Risk Valuation Adjustment, Derivative Liabilities	$ 0.0	$ 0.0
Fair Value Inputs Other Than Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Percentage of Total Fair Value of Fixed Maturities Securities	75.60%
Fair Value Inputs Level 2 Or Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Percentage of Total Fair Value of Fixed Maturities Securities	2.60%
Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Percentage of Total Fair Value of Fixed Maturities Securities	24.40%
Fair Value, Inputs, Level 2 \| Pricing Service
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Percentage of Total Fair Value of Fixed Maturities Securities	56.00%
Fair Value, Inputs, Level 2 \| Other Observable Market Data
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Percentage of Total Fair Value of Fixed Maturities Securities	17.00%

Available For Sale Securities, Percent Of Total Fair Value

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- Definition

Fair Value Additional Information

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- Definition

Loans ceded to reinsurers. These loans use insurance policy funds such as cash surrender values as collateral.

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- Definition

Amount of credit risk valuation adjustment to derivative assets to properly reflect the credit quality of the counterparties.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 35
-Paragraph 18L
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482134/820-10-35-18L

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Amount of credit risk valuation adjustment to derivative liabilities to properly reflect the credit quality of the entity.

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