Investments - Mortgage loans amortized cost by debt service coverage ratio distribution and year of origination (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Debt and Equity Securities, FV-NI [Line Items]
Mortgage loans, net	$ 821	$ 746
Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	827	754
Allowance	(6)	(8)
Mortgage loans, net	821	746
Below 1.0 | Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	0	0
1.0 - 1.25 | Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	46	46
1.26 - 1.50 | Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	160	201
Above 1.50 | Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	621	$ 507
2016 and prior | Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	115
2016 and prior | Below 1.0 | Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	0
2016 and prior | 1.0 - 1.25 | Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	11
2016 and prior | 1.26 - 1.50 | Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	39
2016 and prior | Above 1.50 | Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	65
2017 | Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	44
2017 | Below 1.0 | Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	0
2017 | 1.0 - 1.25 | Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	0
2017 | 1.26 - 1.50 | Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	5
2017 | Above 1.50 | Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	39
2018 | Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	106
2018 | Below 1.0 | Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	0
2018 | 1.0 - 1.25 | Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	0
2018 | 1.26 - 1.50 | Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	0
2018 | Above 1.50 | Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	106
2019 | Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	270
2019 | Below 1.0 | Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	0
2019 | 1.0 - 1.25 | Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	25
2019 | 1.26 - 1.50 | Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	104
2019 | Above 1.50 | Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	141
2020 | Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	77
2020 | Below 1.0 | Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	0
2020 | 1.0 - 1.25 | Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	10
2020 | 1.26 - 1.50 | Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	0
2020 | Above 1.50 | Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	67
Current | Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	215
Current | Below 1.0 | Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	0
Current | 1.0 - 1.25 | Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	0
Current | 1.26 - 1.50 | Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	12
Current | Above 1.50 | Mortgage loans on real estate
Debt and Equity Securities, FV-NI [Line Items]
Amortized cost before allowance	$ 203