Investments - Mortgage loans amortized cost by debt service coverage ratio distribution and year of origination (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost, net	$ 781	$ 762
Mortgage loans
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	788	769
Allowance	(7)	(7)
Amortized cost, net	781	762
Mortgage loans | 2018 and prior
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	159
Mortgage loans | 2019
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	238
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	197
Mortgage loans | 2022
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	102
Mortgage loans | Current
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	40
Below 1.0 | Mortgage loans
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	18	18
Below 1.0 | Mortgage loans | 2018 and prior
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 | 2022
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	18
Below 1.0 | Mortgage loans | Current
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	0
1.0 - 1.25 | Mortgage loans
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	20	42
1.0 - 1.25 | Mortgage loans | 2018 and prior
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	10
1.0 - 1.25 | Mortgage loans | 2019
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	0
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 | 2022
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	0
1.26 - 1.50 | Mortgage loans
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	134	151
1.26 - 1.50 | Mortgage loans | 2018 and prior
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	41
1.26 - 1.50 | Mortgage loans | 2019
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	66
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 | 2022
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	7
1.26 - 1.50 | Mortgage loans | Current
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	8
Above 1.50 | Mortgage loans
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	616	$ 558
Above 1.50 | Mortgage loans | 2018 and prior
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	108
Above 1.50 | Mortgage loans | 2019
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	172
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	185
Above 1.50 | Mortgage loans | 2022
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	77
Above 1.50 | Mortgage loans | Current
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	$ 32