Investments - Schedule of Carrying Value for Limited Partnership Interests (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Debt and Equity Securities, FV-NI [Line Items]
Limited partnership interests	$ 8,562	$ 8,380
EMA
Debt and Equity Securities, FV-NI [Line Items]
Limited partnership interests	7,416	7,215
Fair Value
Debt and Equity Securities, FV-NI [Line Items]
Limited partnership interests	1,146	1,165
Private equity
Debt and Equity Securities, FV-NI [Line Items]
Limited partnership interests	7,266	7,154
Private equity | EMA
Debt and Equity Securities, FV-NI [Line Items]
Limited partnership interests	6,144	6,015
Private equity | Fair Value
Debt and Equity Securities, FV-NI [Line Items]
Limited partnership interests	1,122	1,139
Real estate
Debt and Equity Securities, FV-NI [Line Items]
Limited partnership interests	1,138	1,085
Real estate | EMA
Debt and Equity Securities, FV-NI [Line Items]
Limited partnership interests	1,114	1,059
Real estate | Fair Value
Debt and Equity Securities, FV-NI [Line Items]
Limited partnership interests	24	26
Other
Debt and Equity Securities, FV-NI [Line Items]
Limited partnership interests	158	141
Other | EMA
Debt and Equity Securities, FV-NI [Line Items]
Limited partnership interests	158	141
Other | Fair Value
Debt and Equity Securities, FV-NI [Line Items]
Limited partnership interests	$ 0	$ 0