Investments - Mortgage loans amortized cost by debt service coverage ratio distribution and year of origination (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost, net	$ 762	$ 821
Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	769	827
Allowance	(7)	(6)
Amortized cost, net	762	821
Mortgage loans on real estate | 2017 and prior
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	83
Mortgage loans on real estate | 2018
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	78
Mortgage loans on real estate | 2019
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	238
Mortgage loans on real estate | 2020
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	52
Mortgage loans on real estate | 2021
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	217
Mortgage loans on real estate | Current
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	101
Below 1.0 | Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	18	0
Below 1.0 | Mortgage loans on real estate | 2017 and prior
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	0
Below 1.0 | Mortgage loans on real estate | 2018
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	0
Below 1.0 | Mortgage loans on real estate | 2019
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	0
Below 1.0 | Mortgage loans on real estate | 2020
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	0
Below 1.0 | Mortgage loans on real estate | 2021
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	0
Below 1.0 | Mortgage loans on real estate | Current
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	18
1.0 - 1.25 | Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	42	46
1.0 - 1.25 | Mortgage loans on real estate | 2017 and prior
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	10
1.0 - 1.25 | Mortgage loans on real estate | 2018
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	0
1.0 - 1.25 | Mortgage loans on real estate | 2019
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	0
1.0 - 1.25 | Mortgage loans on real estate | 2020
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	10
1.0 - 1.25 | Mortgage loans on real estate | 2021
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	0
1.0 - 1.25 | Mortgage loans on real estate | Current
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	22
1.26 - 1.50 | Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	151	160
1.26 - 1.50 | Mortgage loans on real estate | 2017 and prior
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	37
1.26 - 1.50 | Mortgage loans on real estate | 2018
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	5
1.26 - 1.50 | Mortgage loans on real estate | 2019
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	102
1.26 - 1.50 | Mortgage loans on real estate | 2020
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	0
1.26 - 1.50 | Mortgage loans on real estate | 2021
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	0
1.26 - 1.50 | Mortgage loans on real estate | Current
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	7
Above 1.50 | Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	558	$ 621
Above 1.50 | Mortgage loans on real estate | 2017 and prior
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	36
Above 1.50 | Mortgage loans on real estate | 2018
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	73
Above 1.50 | Mortgage loans on real estate | 2019
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	136
Above 1.50 | Mortgage loans on real estate | 2020
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	42
Above 1.50 | Mortgage loans on real estate | 2021
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	217
Above 1.50 | Mortgage loans on real estate | Current
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	$ 54