Long-Duration Insurance Contracts - Weighted-Average Durations of LFPB (Details)	Mar. 31, 2025	Mar. 31, 2024
Whole Life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Weighted-average duration	19 years 6 months	17 years 10 months 24 days
Term Life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Weighted-average duration	15 years 9 months 18 days	16 years 7 months 6 days
Experience life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Weighted-average duration	10 years	10 years 3 months 18 days
Limited-Pay Whole Life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Weighted-average duration	24 years 6 months	21 years 10 months 24 days
Supplemental health
Liability for Future Policy Benefit, by Product Segment [Line Items]
Weighted-average duration	11 years 4 months 24 days	10 years 9 months 18 days
SPIA (life contingent)
Liability for Future Policy Benefit, by Product Segment [Line Items]
Weighted-average duration	7 years 6 months	7 years 7 months 6 days