Long-Duration Insurance Contracts - Weighted-Average Durations of LFPB (Details)	Mar. 31, 2024	Mar. 31, 2023
Whole Life Insurance
Liability for Future Policy Benefit, by Product Segment [Line Items]
Weighted-average duration	17 years 10 months 24 days	18 years
Term Life Insurance
Liability for Future Policy Benefit, by Product Segment [Line Items]
Weighted-average duration	16 years 7 months 6 days	17 years
Experience Life Insurance
Liability for Future Policy Benefit, by Product Segment [Line Items]
Weighted-average duration	10 years 3 months 18 days	11 years
Limited Pay Whole Life Insurance
Liability for Future Policy Benefit, by Product Segment [Line Items]
Weighted-average duration	21 years 10 months 24 days	23 years
Supplemental health
Liability for Future Policy Benefit, by Product Segment [Line Items]
Weighted-average duration	10 years 9 months 18 days	10 years 2 months 12 days
Life Contingent SPIA Retirement Insurance
Liability for Future Policy Benefit, by Product Segment [Line Items]
Weighted-average duration	7 years 7 months 6 days	8 years