Investments - Mortgage loans amortized cost by debt service coverage ratio distribution and year of origination (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost, net	$ 848	$ 821
Mortgage loans
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	855	827
Allowance	(7)	(6)
Amortized cost, net	848	821
Mortgage loans | 2017 and prior
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	155
Mortgage loans | 2018
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	105
Mortgage loans | 2019
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	239
Mortgage loans | 2020
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	52
Mortgage loans | 2021
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	215
Mortgage loans | Current
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	89
Below 1.0 | Mortgage loans
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	18	0
Below 1.0 | Mortgage loans | 2017 and prior
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	0
Below 1.0 | Mortgage loans | 2018
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	0
Below 1.0 | Mortgage loans | 2019
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	0
Below 1.0 | Mortgage loans | 2020
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	0
Below 1.0 | Mortgage loans | 2021
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	0
Below 1.0 | Mortgage loans | Current
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	18
1.0 - 1.25 | Mortgage loans
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	92	46
1.0 - 1.25 | Mortgage loans | 2017 and prior
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	35
1.0 - 1.25 | Mortgage loans | 2018
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	0
1.0 - 1.25 | Mortgage loans | 2019
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	25
1.0 - 1.25 | Mortgage loans | 2020
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	10
1.0 - 1.25 | Mortgage loans | 2021
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	0
1.0 - 1.25 | Mortgage loans | Current
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	22
1.26 - 1.50 | Mortgage loans
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	141	160
1.26 - 1.50 | Mortgage loans | 2017 and prior
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	18
1.26 - 1.50 | Mortgage loans | 2018
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	0
1.26 - 1.50 | Mortgage loans | 2019
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	104
1.26 - 1.50 | Mortgage loans | 2020
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	0
1.26 - 1.50 | Mortgage loans | 2021
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	12
1.26 - 1.50 | Mortgage loans | Current
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	7
Above 1.50 | Mortgage loans
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	604	$ 621
Above 1.50 | Mortgage loans | 2017 and prior
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	102
Above 1.50 | Mortgage loans | 2018
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	105
Above 1.50 | Mortgage loans | 2019
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	110
Above 1.50 | Mortgage loans | 2020
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	42
Above 1.50 | Mortgage loans | 2021
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	203
Above 1.50 | Mortgage loans | Current
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	$ 42