Investments (Distribution By Contractual Maturity Of Available-For-Sale and Held-To-Maturity Investments) (Detail) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Variable Interest Entity Primary Beneficiary [Member]
Held To Maturity Securities [Abstract]
Total Held-To-Maturity, amortized cost	$ 890	$ 2,689
Total Held-To-Maturity, fair value	573	$ 2,401
Fixed Maturities [Member]
Available For Sale Securities [Abstract]
Due in one year or less	499
Due after one year through five years	1,685
Due after five years through ten years	960
Due after ten years	1,311
Mortgage-Backed and Asset-Backed	1,422
Total Available-For-Sale, amortized cost	5,877
Due in one year or less	499
Due after one year through five years	1,720
Due after five years through ten years	934
Due after ten years	1,462
Mortgage-Backed and Asset-Backed	1,422
Total Available-For-Sale, fair value	6,037
Fixed Maturities [Member] | 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	573
Mortgage-Backed and Asset-Backed	0
Total Held-To-Maturity, fair value	$ 573