Investments (Schedule Of Amortized Cost And Fair Value Of Fixed Maturities And Related Other-Than-Temporary Impairment Recognized In Accumulated Other Comprehensive Income) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Investment [Line Items]
Document Period End Date	Dec. 31, 2015
Available for sale, Amortized Cost	$ 43,149	$ 47,826
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	1,168	1,871
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(730)	(302)
Available for sale, Fair Value	43,587	49,395
Available for sale, OTTI recognized in AOCI	(42)	(8)
Held to maturity, Amortized Cost	8,430	7,331
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	190	266
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(68)	(8)
Held to maturity, Fair Value	8,552	7,589
Held to maturity, OTTI recognized in AOCI		0
U.S. Treasury and agency
Investment [Line Items]
Available for sale, Amortized Cost	2,481	2,741
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	52	87
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(5)	(8)
Available for sale, Fair Value	2,528	2,820
Available for sale, OTTI recognized in AOCI	0	0
Held to maturity, Amortized Cost	733	832
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	13	20
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(1)	(2)
Held to maturity, Fair Value	745	850
Held to maturity, OTTI recognized in AOCI	0	0
Foreign
Investment [Line Items]
Available for sale, Amortized Cost	13,190	14,703
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	468	629
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(213)	(90)
Available for sale, Fair Value	13,445	15,242
Available for sale, OTTI recognized in AOCI	(13)	0
Held to maturity, Amortized Cost	763	916
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	30	47
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(8)	0
Held to maturity, Fair Value	785	963
Held to maturity, OTTI recognized in AOCI	0	0
Corporate securities
Investment [Line Items]
Available for sale, Amortized Cost	15,028	16,897
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	355	704
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(454)	(170)
Available for sale, Fair Value	14,929	17,431
Available for sale, OTTI recognized in AOCI	(28)	(7)
Held to maturity, Amortized Cost	3,054	2,323
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	57	102
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(55)	(2)
Held to maturity, Fair Value	3,056	2,423
Held to maturity, OTTI recognized in AOCI	0	0
Mortgage backed-securities
Investment [Line Items]
Available for sale, Amortized Cost	9,827	10,011
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	183	304
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(52)	(29)
Available for sale, Fair Value	9,958	10,286
Available for sale, OTTI recognized in AOCI	(1)	(1)
Held to maturity, Amortized Cost	1,707	1,983
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	38	57
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(2)	(1)
Held to maturity, Fair Value	1,743	2,039
Held to maturity, OTTI recognized in AOCI	0	0
States, municipalities, and political subdivisions
Investment [Line Items]
Available for sale, Amortized Cost	2,623	3,474
Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax	110	147
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(6)	(5)
Available for sale, Fair Value	2,727	3,616
Available for sale, OTTI recognized in AOCI	0	0
Held to maturity, Amortized Cost	2,173	1,277
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	52	40
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(2)	(3)
Held to maturity, Fair Value	2,223	1,314
Held to maturity, OTTI recognized in AOCI	$ 0	$ 0