Future Policy Benefits - Actual Experience and Expected Experience for Mortality and Lapses (Details)	Mar. 31, 2024	Dec. 31, 2023
Actual experience | Traditional Life
Liability for Future Policy Benefit, Activity [Line Items]
Mortality rate	1.20%	1.70%
Lapse rate	0.00%	0.00%
Actual experience | Immediate Annuities
Liability for Future Policy Benefit, Activity [Line Items]
Mortality rate	3.20%	3.20%
Lapse rate	0.00%	0.00%
Actual experience | PRT
Liability for Future Policy Benefit, Activity [Line Items]
Mortality rate	4.20%	3.20%
Lapse rate	0.00%	0.00%
Expected experience | Traditional Life
Liability for Future Policy Benefit, Activity [Line Items]
Mortality rate	1.40%	1.40%
Lapse rate	0.40%	0.30%
Expected experience | Immediate Annuities
Liability for Future Policy Benefit, Activity [Line Items]
Mortality rate	2.30%	1.80%
Lapse rate	0.00%	0.00%
Expected experience | PRT
Liability for Future Policy Benefit, Activity [Line Items]
Mortality rate	2.80%	2.30%
Lapse rate	0.00%	0.00%