Investments - Mortgage loans amortized cost by debt service coverage ratio distribution and year of origination (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost, net	$ 823	$ 762
Mortgage loans
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	833	769
Allowance	(10)	(7)
Amortized cost, net	823	762
Mortgage loans | 2018 and prior
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	146
Mortgage loans | 2019
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	237
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	99
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	45	42
1.0 - 1.25 | Mortgage loans | 2018 and prior
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	23
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	12
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	174	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	65
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	0
1.26 - 1.50 | Mortgage loans | 2022
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	20
1.26 - 1.50 | Mortgage loans | Current
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	48
Above 1.50 | Mortgage loans
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	596	$ 558
Above 1.50 | Mortgage loans | 2018 and prior
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	82
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	64
Above 1.50 | Mortgage loans | Current
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	$ 51