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, 2021 USD ($) claim	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Increase (decrease) in claims and claims expense
Incurred claims and allocated claim adjustment expenses, net of recoverables	$ 1,345
Cumulative paid claims and allocated claims adjustment expenses, net of recoverables	1,184
All outstanding liabilities before 2017, net of recoverables	0
Net outstanding liabilities	161
Accident Year 2017
Increase (decrease) in claims and claims expense
Incurred claims and allocated claim adjustment expenses, net of recoverables	183	$ 183	$ 183	$ 186	$ 211
IBNR reserves plus expected development on reported claims	$ 0
Cumulative number of reported claims | claim	302,100
Cumulative paid claims and allocated claims adjustment expenses, net of recoverables	$ 183	183	182	178	$ 105
Accident Year 2018
Increase (decrease) in claims and claims expense
Incurred claims and allocated claim adjustment expenses, net of recoverables	203	203	205	235
IBNR reserves plus expected development on reported claims	$ 0
Cumulative number of reported claims | claim	269,095
Cumulative paid claims and allocated claims adjustment expenses, net of recoverables	$ 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	239	257
IBNR reserves plus expected development on reported claims	$ 0
Cumulative number of reported claims | claim	306,998
Cumulative paid claims and allocated claims adjustment expenses, net of recoverables	$ 242	234	$ 158
Accident Year 2020
Increase (decrease) in claims and claims expense
Incurred claims and allocated claim adjustment expenses, net of recoverables	293	297
IBNR reserves plus expected development on reported claims	$ 9
Cumulative number of reported claims | claim	410,031
Cumulative paid claims and allocated claims adjustment expenses, net of recoverables	$ 284	$ 184
Accident Year 2021
Increase (decrease) in claims and claims expense
Incurred claims and allocated claim adjustment expenses, net of recoverables	424
IBNR reserves plus expected development on reported claims	$ 152
Cumulative number of reported claims | claim	465,525
Cumulative paid claims and allocated claims adjustment expenses, net of recoverables	$ 272