Investments - Schedule of Carrying Value for Limited Partnership Interests (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Debt and Equity Securities, FV-NI [Line Items]
Limited partnership interests	$ 8,363	$ 8,114
EMA
Debt and Equity Securities, FV-NI [Line Items]
Limited partnership interests	7,169	6,868
Fair Value
Debt and Equity Securities, FV-NI [Line Items]
Limited partnership interests	1,194	1,246
Private equity
Debt and Equity Securities, FV-NI [Line Items]
Limited partnership interests	7,092	6,589
Private equity | EMA
Debt and Equity Securities, FV-NI [Line Items]
Limited partnership interests	5,925	5,372
Private equity | Fair Value
Debt and Equity Securities, FV-NI [Line Items]
Limited partnership interests	1,167	1,217
Real estate
Debt and Equity Securities, FV-NI [Line Items]
Limited partnership interests	1,103	1,042
Real estate | EMA
Debt and Equity Securities, FV-NI [Line Items]
Limited partnership interests	1,076	1,013
Real estate | Fair Value
Debt and Equity Securities, FV-NI [Line Items]
Limited partnership interests	27	29
Other
Debt and Equity Securities, FV-NI [Line Items]
Limited partnership interests	168	483
Other | EMA
Debt and Equity Securities, FV-NI [Line Items]
Limited partnership interests	168	483
Other | Fair Value
Debt and Equity Securities, FV-NI [Line Items]
Limited partnership interests	$ 0	$ 0