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 $ in Millions	Dec. 31, 2023 USD ($) claim	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Increase (decrease) in claims and claims expense
Incurred claims and allocated claim adjustment expenses, net of recoverables	$ 1,826
Cumulative paid claims and allocated claims adjustment expenses, net of recoverables	1,651
All outstanding liabilities before 2019, net of recoverables	0
Liabilities for claims and claim adjustment expenses, net of recoverables	175
Accident Year 2019
Increase (decrease) in claims and claims expense
Incurred claims and allocated claim adjustment expenses, net of recoverables	242	$ 242	$ 242	$ 239	$ 257
IBNR reserves plus expected development on reported claims	$ 0
Cumulative number of reported claims | claim	313,017
Cumulative paid claims and allocated claims adjustment expenses, net of recoverables	$ 242	242	242	234	158
Accident Year 2020
Increase (decrease) in claims and claims expense
Incurred claims and allocated claim adjustment expenses, net of recoverables	291	294	293	297	0
IBNR reserves plus expected development on reported claims	$ 1
Cumulative number of reported claims | claim	415,364
Cumulative paid claims and allocated claims adjustment expenses, net of recoverables	$ 290	290	284	184	0
Accident Year 2021
Increase (decrease) in claims and claims expense
Incurred claims and allocated claim adjustment expenses, net of recoverables	415	420	424	0	0
IBNR reserves plus expected development on reported claims	$ 2
Cumulative number of reported claims | claim	677,649
Cumulative paid claims and allocated claims adjustment expenses, net of recoverables	$ 414	408	272		0
Accident Year 2022
Increase (decrease) in claims and claims expense
Incurred claims and allocated claim adjustment expenses, net of recoverables	402	437	0	0	0
IBNR reserves plus expected development on reported claims	$ 8
Cumulative number of reported claims | claim	587,462
Cumulative paid claims and allocated claims adjustment expenses, net of recoverables	$ 393	275	0	0	0
Accident Year 2023
Increase (decrease) in claims and claims expense
Incurred claims and allocated claim adjustment expenses, net of recoverables	476	0	0	0	0
IBNR reserves plus expected development on reported claims	$ 164
Cumulative number of reported claims | claim	413,651
Cumulative paid claims and allocated claims adjustment expenses, net of recoverables	$ 312	$ 0	$ 0	$ 0	$ 0