Fair Value of Financial Instruments Additional Information (Detail) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Ceded Policy Loans	$ 3,384.7	$ 3,353.8
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	23.80%
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	57.50%
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	17.50%
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	76.20%
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	1.20%