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	Jun. 30, 2016	Dec. 31, 2015
Investment [Line Items]
Held to maturity, Amortized Cost	$ 11,090	$ 8,430
Held to maturity, Gross Unrealized Appreciation	497	190
Held to maturity, Gross Unrealized Depreciation	(6)	(68)
Held to maturity, at Fair Value	11,581	8,552
Available for sale, at amortized cost	77,436	43,149
Available-for-sale,Gross Unrealized Gain	2,719	1,168
Available-for-sale, Gross Unrealized Depreciation	(204)	(730)
Available for sale, Fair Value	79,951	43,587
Available for sale, OTTI recognized in AOCI	(30)	(42)
U.S. Treasury And Agency [Member]
Investment [Line Items]
Held to maturity, Amortized Cost	686	733
Held to maturity, Gross Unrealized Appreciation	30	13
Held to maturity, Gross Unrealized Depreciation	0	(1)
Held to maturity, at Fair Value	716	745
Held to maturity, OTTI recognized in AOCI	0	0
Available for sale, at amortized cost	2,595	2,481
Available-for-sale,Gross Unrealized Gain	103	52
Available-for-sale, Gross Unrealized Depreciation	0	(5)
Available for sale, Fair Value	2,698	2,528
Available for sale, OTTI recognized in AOCI	0	0
Foreign [Member]
Investment [Line Items]
Held to maturity, Amortized Cost	730	763
Held to maturity, Gross Unrealized Appreciation	44	30
Held to maturity, Gross Unrealized Depreciation	(1)	(8)
Held to maturity, at Fair Value	773	785
Held to maturity, OTTI recognized in AOCI	0	0
Available for sale, at amortized cost	21,633	13,190
Available-for-sale,Gross Unrealized Gain	916	468
Available-for-sale, Gross Unrealized Depreciation	(69)	(213)
Available for sale, Fair Value	22,480	13,445
Available for sale, OTTI recognized in AOCI	(13)	(13)
Corporate [Member]
Investment [Line Items]
Held to maturity, Amortized Cost	2,882	3,054
Held to maturity, Gross Unrealized Appreciation	137	57
Held to maturity, Gross Unrealized Depreciation	(4)	(55)
Held to maturity, at Fair Value	3,015	3,056
Held to maturity, OTTI recognized in AOCI	0	0
Available for sale, at amortized cost	21,714	15,028
Available-for-sale,Gross Unrealized Gain	846	355
Available-for-sale, Gross Unrealized Depreciation	(125)	(454)
Available for sale, Fair Value	22,435	14,929
Available for sale, OTTI recognized in AOCI	(16)	(28)
Collateralized Mortgage Backed Securities [Member]
Investment [Line Items]
Held to maturity, Amortized Cost	1,600	1,707
Held to maturity, Gross Unrealized Appreciation	77	38
Held to maturity, Gross Unrealized Depreciation	(1)	(2)
Held to maturity, at Fair Value	1,676	1,743
Held to maturity, OTTI recognized in AOCI	0	0
Available for sale, at amortized cost	12,369	9,827
Available-for-sale,Gross Unrealized Gain	400	183
Available-for-sale, Gross Unrealized Depreciation	(5)	(52)
Available for sale, Fair Value	12,764	9,958
Available for sale, OTTI recognized in AOCI	(1)	(1)
States, Municipalities, And Political Subdivisions [Member]
Investment [Line Items]
Held to maturity, Amortized Cost	5,192	2,173
Held to maturity, Gross Unrealized Appreciation	209	52
Held to maturity, Gross Unrealized Depreciation	0	(2)
Held to maturity, at Fair Value	5,401	2,223
Held to maturity, OTTI recognized in AOCI	0	0
Available for sale, at amortized cost	19,125	2,623
Available-for-sale,Gross Unrealized Gain	454	110
Available-for-sale, Gross Unrealized Depreciation	(5)	(6)
Available for sale, Fair Value	19,574	2,727
Available for sale, OTTI recognized in AOCI	$ 0	$ 0