Investments - Narrative (Details) $ in Millions	Mar. 31, 2024 USD ($) security	Dec. 31, 2023 USD ($)
Schedule of Investments [Line Items]
Unfunded commitments to limited partnerships	$ 443	$ 418
Percentage (based on amount of unrealized loss) of available for sale fixed maturities that are in an unrealized loss position and rated investment grade	95.00%
Percentage (based on fair value) of available for sale fixed maturities that are in an unrealized loss position and rated investment grade	95.00%
Multifamily
Schedule of Investments [Line Items]
Percent of real-estate related investments by property type	91.00%	92.00%
Fixed maturities:
Schedule of Investments [Line Items]
Gross unrealized losses on fixed maturities	$ 448	$ 470
Number of fixed maturity securities in an unrealized loss position | security	1,450