Investments (Distribution By Contractual Maturity Of Available-For-Sale and Held-To-Maturity Investments) (Detail) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Available For Sale Securities [Abstract]
Due in one year or less	$ 418
Due after one year through five years	159
Due after five years through ten years	205
Due after ten years	435
Mortgage-backed and asset-backed	327
Total fixed-maturity investments	1,544
Due in one year or less	417
Due after one year through five years	155
Due after five years through ten years	179
Due after ten years	342
Mortgage-backed and asset-backed	304
Total fixed-maturity investments	$ 1,397	$ 1,557
Investment, Type [Extensible Enumeration]	Fixed Maturities [Member]	Fixed Maturities [Member]