Investments - Summary of Fair Value, Including Financial Guarantee, and Weighted-Average Underlying Rating, Excluding Financial Guarantee, of Insured Securities (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Standard & Poor's, B Rating [Member]
Schedule of Investments [Line Items]
Fair value of securities that include benefit of guarantees provided by financial guarantors		$ 403
Standard & Poor's, B- Rating [Member]
Schedule of Investments [Line Items]
Fair value of securities that include benefit of guarantees provided by financial guarantors	$ 446
Municipal Bonds [Member] | Standard & Poor's, B Rating [Member]
Schedule of Investments [Line Items]
Fair value of securities that include benefit of guarantees provided by financial guarantors		10
Municipal Bonds [Member] | Standard & Poor's, B- Rating [Member]
Schedule of Investments [Line Items]
Fair value of securities that include benefit of guarantees provided by financial guarantors	9
Mortgage And Other Asset Backed Securities [Member] | Standard & Poor's, B Rating [Member]
Schedule of Investments [Line Items]
Fair value of securities that include benefit of guarantees provided by financial guarantors		$ 394
Mortgage And Other Asset Backed Securities [Member] | Standard & Poor's, B- Rating [Member]
Schedule of Investments [Line Items]
Fair value of securities that include benefit of guarantees provided by financial guarantors	$ 436