Long-Duration Insurance Contracts - Actual and Expected Experience of Mortality Rate and Lapse Rate (Details)	Mar. 31, 2026	Mar. 31, 2025
Whole Life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Mortality / Morbidity, actual experience	0.80%	1.00%
Mortality / Morbidity, expected experience	0.80%	0.80%
Lapses, actual experience	3.60%	3.10%
Lapses, expected experience	3.30%	3.70%
Term Life | Minimum
Liability for Future Policy Benefit, by Product Segment [Line Items]
Mortality / Morbidity, actual experience	0.10%	0.10%
Mortality / Morbidity, expected experience	0.10%	0.10%
Lapses, actual experience	1.70%	2.60%
Lapses, expected experience	4.70%	5.00%
Term Life | Maximum
Liability for Future Policy Benefit, by Product Segment [Line Items]
Mortality / Morbidity, actual experience	0.40%	0.10%
Mortality / Morbidity, expected experience	0.50%	0.50%
Lapses, actual experience	4.10%	3.80%
Lapses, expected experience	4.80%	5.10%
Experience life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Mortality / Morbidity, actual experience	1.90%	2.30%
Mortality / Morbidity, expected experience	2.00%	1.90%
Lapses, actual experience	4.10%	3.30%
Lapses, expected experience	3.20%	3.00%
Limited-Pay Whole Life
Liability for Future Policy Benefit, by Product Segment [Line Items]
Mortality / Morbidity, actual experience	0.10%	0.40%
Mortality / Morbidity, expected experience	0.30%	0.30%
Lapses, actual experience	4.80%	3.80%
Lapses, expected experience	3.60%	4.00%
Supplemental health
Liability for Future Policy Benefit, by Product Segment [Line Items]
Mortality / Morbidity, actual experience	31.60%	41.90%
Mortality / Morbidity, expected experience	27.60%	26.80%
Lapses, actual experience	10.60%	13.90%
Lapses, expected experience	10.30%	14.00%