Investments (Distribution By Contractual Maturity Of Available-For-Sale and Held-To-Maturity Investments) (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Held To Maturity Securities [Abstract]
Total Held-To-Maturity, amortized cost	$ 2,742	$ 2,757
Total Held-To-Maturity, fair value	2,635	2,632
Fixed Maturities [Member]
Available For Sale Securities [Abstract]
Due in one year or less	839
Due after one year through five years	1,420
Due after five years through ten years	905
Due after ten years	1,467
Mortgage-Backed and Asset-Backed	1,574
Total Available-For-Sale, amortized cost	6,205
Due in one year or less	841
Due after one year through five years	1,449
Due after five years through ten years	943
Due after ten years	1,507
Mortgage-Backed and Asset-Backed	1,559
Total Available-For-Sale, fair value	6,299
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	2,742
Mortgage-Backed and Asset-Backed	0
Total Held-To-Maturity, amortized cost	2,742
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	2,635
Mortgage-Backed and Asset-Backed	0
Total Held-To-Maturity, fair value	$ 2,635