Investments - Summary of Sources of Collateral Received and Various Investment Agreement in which Collateral Pledged (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Investment [Line Items]
Fair Value Of Securities Deposited With Governmental Authorities	$ 29	$ 24
Fair Value of Securities Deposited in Connection wtih Letter of Credit	$ 1	1
Standard & Poor's, B Rating [Member]
Investment [Line Items]
Investment Owned, at Fair Value		482
Standard & Poor's, B Rating [Member] | Municipal Bonds [Member]
Investment [Line Items]
Investment Owned, at Fair Value		$ 9