Reserve for Future Policy Benefits and Contractholder Funds - Schedule of Incurred Claims, Cumulative Paid Claims and Allocated Claim Adjustment Expenses, Net of Recoverables (Details) - Group and individual accident and health claim in Thousands, $ in Millions	Dec. 31, 2024 USD ($) claim	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Increase (decrease) in claims and claims expense
Incurred claims and allocated claim adjustment expenses, net of recoverables	$ 2,098
Cumulative paid claims and allocated claims adjustment expenses, net of recoverables	1,912
All outstanding liabilities before 2020, net of recoverables	0
Liabilities for claims and claim adjustment expenses, net of recoverables	186
Accident Year 2020
Increase (decrease) in claims and claims expense
Incurred claims and allocated claim adjustment expenses, net of recoverables	290	$ 291	$ 294	$ 293	$ 297
IBNR reserves plus expected development on reported claims	$ 0
Cumulative number of reported claims (in thousands) | claim	415
Cumulative paid claims and allocated claims adjustment expenses, net of recoverables	$ 290	290	290	284	184
Accident Year 2021
Increase (decrease) in claims and claims expense
Incurred claims and allocated claim adjustment expenses, net of recoverables	417	415	420	424	0
IBNR reserves plus expected development on reported claims	$ 0
Cumulative number of reported claims (in thousands) | claim	679
Cumulative paid claims and allocated claims adjustment expenses, net of recoverables	$ 416	413	408	272	0
Accident Year 2022
Increase (decrease) in claims and claims expense
Incurred claims and allocated claim adjustment expenses, net of recoverables	399	402	437	0	0
IBNR reserves plus expected development on reported claims	$ 1
Cumulative number of reported claims (in thousands) | claim	590
Cumulative paid claims and allocated claims adjustment expenses, net of recoverables	$ 398	393	275		0
Accident Year 2023
Increase (decrease) in claims and claims expense
Incurred claims and allocated claim adjustment expenses, net of recoverables	455	476	0	0	0
IBNR reserves plus expected development on reported claims	$ 10
Cumulative number of reported claims (in thousands) | claim	582
Cumulative paid claims and allocated claims adjustment expenses, net of recoverables	$ 446	312	0	0	0
Accident Year 2024
Increase (decrease) in claims and claims expense
Incurred claims and allocated claim adjustment expenses, net of recoverables	537	0	0	0	0
IBNR reserves plus expected development on reported claims	$ 175
Cumulative number of reported claims (in thousands) | claim	456
Cumulative paid claims and allocated claims adjustment expenses, net of recoverables	$ 362	$ 0	$ 0	$ 0	$ 0