Reserve for Future Policy Benefits and Contractholder Funds - Claims and allocated claim adjustment expenses, net of reinsurance (Details) - Group and individual accident and health $ in Millions	Dec. 31, 2022 USD ($) claim	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Increase (decrease) in claims and claims expense
Incurred claims and allocated claim adjustment expenses, net of recoverables	$ 1,596
Cumulative paid claims and allocated claims adjustment expenses, net of recoverables	1,418
All outstanding liabilities before 2018, net of recoverables	0
Liabilities for claims and claim adjustment expenses, net of recoverables	178
Accident Year 2018
Increase (decrease) in claims and claims expense
Incurred claims and allocated claim adjustment expenses, net of recoverables	203	$ 203	$ 203	$ 205	$ 235
IBNR reserves plus expected development on reported claims	$ 0
Cumulative number of reported claims | claim	292,491
Cumulative paid claims and allocated claims adjustment expenses, net of recoverables	$ 203	203	203	201	126
Accident Year 2019
Increase (decrease) in claims and claims expense
Incurred claims and allocated claim adjustment expenses, net of recoverables	242	242	239	257	0
IBNR reserves plus expected development on reported claims	$ 0
Cumulative number of reported claims | claim	311,662
Cumulative paid claims and allocated claims adjustment expenses, net of recoverables	$ 242	242	234	158	0
Accident Year 2020
Increase (decrease) in claims and claims expense
Incurred claims and allocated claim adjustment expenses, net of recoverables	294	293	297	0	0
IBNR reserves plus expected development on reported claims	$ 4
Cumulative number of reported claims | claim	414,634
Cumulative paid claims and allocated claims adjustment expenses, net of recoverables	$ 290	284	184	0	0
Accident Year 2021
Increase (decrease) in claims and claims expense
Incurred claims and allocated claim adjustment expenses, net of recoverables	420	424	0	0	0
IBNR reserves plus expected development on reported claims	$ 12
Cumulative number of reported claims | claim	671,483
Cumulative paid claims and allocated claims adjustment expenses, net of recoverables	$ 408	272	0	0	0
Accident Year 2022
Increase (decrease) in claims and claims expense
Incurred claims and allocated claim adjustment expenses, net of recoverables	437	0	0	0	0
IBNR reserves plus expected development on reported claims	$ 162
Cumulative number of reported claims | claim	427,124
Cumulative paid claims and allocated claims adjustment expenses, net of recoverables	$ 275	$ 0	$ 0	$ 0	$ 0