Investments (Distribution By Contractual Maturity Of Available-For-Sale and Held-To-Maturity Investments) (Detail) - Fixed Maturities [Member] $ in Millions	Dec. 31, 2020 USD ($)
Available For Sale Securities [Abstract]
Due in one year or less	$ 509
Due after one year through five years	363
Due after five years through ten years	266
Due after ten years	637
Mortgage-Backed and Asset-Backed	585
Total Available-For-Sale, amortized cost	2,360
Due in one year or less	511
Due after one year through five years	379
Due after five years through ten years	296
Due after ten years	759
Mortgage-Backed and Asset-Backed	594
Total Available-For-Sale, fair value	$ 2,539