Investments - Schedule of Gross Unrealized Losses by Unrealized Loss Position and Credit Quality (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Investment grade fixed income securities
Investments [Line Items]
Fixed income securities with unrealized loss position less than 20% of amortized cost, net	$ (1,266)
Fixed income securities with unrealized loss position greater than or equal to 20% of amortized cost, net	(78)
Total unrealized losses	(1,344)	$ (1,234)
Below investment grade fixed income securities
Investments [Line Items]
Fixed income securities with unrealized loss position less than 20% of amortized cost, net	(134)
Fixed income securities with unrealized loss position greater than or equal to 20% of amortized cost, net	(26)
Total unrealized losses	(160)	(200)
Fixed income securities
Investments [Line Items]
Fixed income securities with unrealized loss position less than 20% of amortized cost, net	(1,400)
Fixed income securities with unrealized loss position greater than or equal to 20% of amortized cost, net	(104)
Total unrealized losses	$ (1,504)	$ (1,434)