Investments - Mortgage loans amortized cost by debt service coverage ratio distribution and year of origination (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Debt and Equity Securities, FV-NI [Line Items]
Mortgage loans, net	$ 855	$ 821
Mortgage loans
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	862	827
Allowance	(7)	(6)
Mortgage loans, net	855	821
Mortgage loans | 2017 and prior
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	157
Mortgage loans | 2018
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	106
Mortgage loans | 2019
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	270
Mortgage loans | 2020
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	77
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	37
Below 1.0 | Mortgage loans
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	0	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	0
1.0 - 1.25 | Mortgage loans
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	71	46
1.0 - 1.25 | Mortgage loans | 2017 and prior
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	36
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	0
1.26 - 1.50 | Mortgage loans
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	142	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	105
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	649	$ 621
Above 1.50 | Mortgage loans | 2017 and prior
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	103
Above 1.50 | Mortgage loans | 2018
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	106
Above 1.50 | Mortgage loans | 2019
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	140
Above 1.50 | Mortgage loans | 2020
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	67
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	$ 30