Investments (Distribution By Contractual Maturity Of Available-For-Sale and Held-To-Maturity Investments) (Detail) - Fixed Maturities [Member] $ in Millions	Dec. 31, 2019 USD ($)
Available For Sale Securities [Abstract]
Due in one year or less	$ 570
Due after one year through five years	472
Due after five years through ten years	391
Due after ten years	731
Mortgage-Backed and Asset-Backed	820
Total Available-For-Sale, amortized cost	2,984
Due in one year or less	571
Due after one year through five years	480
Due after five years through ten years	411
Due after ten years	820
Mortgage-Backed and Asset-Backed	817
Total Available-For-Sale, fair value	3,099
Variable Interest Entity Primary Beneficiary [Member]
Held To Maturity Securities [Abstract]
Due in one year or less	0
Due after one year through five years	0
Due after five years through ten years	0
Due after ten years	890
Mortgage-Backed and Asset-Backed	0
Total held-to-maturity, amortized cost	890
Due in one year or less	0
Due after one year through five years	0
Due after five years through ten years	0
Due after ten years	892
Mortgage-Backed and Asset-Backed	0
Held-To-Maturity Securities Fair Value	$ 892