Long-Duration Insurance Contracts - Weighted-Average Durations of LFPB (Details)	Mar. 31, 2026	Mar. 31, 2025
Whole Life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Weighted-average duration	19 years 10 months 24 days	19 years 6 months
Term Life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Weighted-average duration	15 years 8 months 12 days	15 years 9 months 18 days
Experience life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Weighted-average duration	9 years 6 months	10 years
Limited-Pay Whole Life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Weighted-average duration	24 years 9 months 18 days	24 years 6 months
Supplemental health
Liability for Future Policy Benefit, by Product Segment [Line Items]
Weighted-average duration	11 years 10 months 24 days	11 years 4 months 24 days
SPIA (life contingent)
Liability for Future Policy Benefit, by Product Segment [Line Items]
Weighted-average duration	7 years 4 months 24 days	7 years 6 months