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, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Investment [Line Items]
Held to maturity, Gross Unrealized Appreciation	$ 205	$ 367
Held to maturity, Gross Unrealized Depreciation	(18)	(4)
Held to maturity, Fair Value	6,493	7,633
Held to maturity, OTTI recognized in AOCI
Available for sale, Amortized Cost	47,481	44,666
AvailableforsaleSecuritiesGrossUnrealizedGainAccumulatedInInvestments	1,545	2,725
Available for sale, Gross Unrealized Depreciation	(497)	(85)
Available for sale, Fair Value	48,529	47,306
Available for sale, OTTI recognized in AOCI	(42)	(91)
Held to maturity, Amortized Cost	6,306	7,270
U.S. Treasury And Agency [Member]
Investment [Line Items]
Held to maturity, Gross Unrealized Appreciation	20	39
Held to maturity, Gross Unrealized Depreciation	(3)	0
Held to maturity, Fair Value	859	1,083
Held to maturity, OTTI recognized in AOCI	0	0
Available for sale, Amortized Cost	2,934	3,553
AvailableforsaleSecuritiesGrossUnrealizedGainAccumulatedInInvestments	81	183
Available for sale, Gross Unrealized Depreciation	(36)	(1)
Available for sale, Fair Value	2,979	3,735
Available for sale, OTTI recognized in AOCI	0	0
Held to maturity, Amortized Cost	842	1,044
Foreign [Member]
Investment [Line Items]
Held to maturity, Gross Unrealized Appreciation	36	54
Held to maturity, Gross Unrealized Depreciation	0	0
Held to maturity, Fair Value	912	964
Held to maturity, OTTI recognized in AOCI	0	0
Available for sale, Amortized Cost	14,294	13,016
AvailableforsaleSecuritiesGrossUnrealizedGainAccumulatedInInvestments	405	711
Available for sale, Gross Unrealized Depreciation	(98)	(14)
Available for sale, Fair Value	14,601	13,713
Available for sale, OTTI recognized in AOCI	0	0
Held to maturity, Amortized Cost	876	910
Corporate Securities [Member]
Investment [Line Items]
Held to maturity, Gross Unrealized Appreciation	87	142
Held to maturity, Gross Unrealized Depreciation	0	0
Held to maturity, Fair Value	2,047	2,275
Held to maturity, OTTI recognized in AOCI	0	0
Available for sale, Amortized Cost	16,664	15,529
AvailableforsaleSecuritiesGrossUnrealizedGainAccumulatedInInvestments	753	1,210
Available for sale, Gross Unrealized Depreciation	(151)	(31)
Available for sale, Fair Value	17,266	16,708
Available for sale, OTTI recognized in AOCI	(6)	(7)
Held to maturity, Amortized Cost	1,960	2,133
Mortgage Backed-Securities [Member]
Investment [Line Items]
Held to maturity, Gross Unrealized Appreciation	43	88
Held to maturity, Gross Unrealized Depreciation	0	0
Held to maturity, Fair Value	1,483	2,116
Held to maturity, OTTI recognized in AOCI	0	0
Available for sale, Amortized Cost	10,294	10,051
AvailableforsaleSecuritiesGrossUnrealizedGainAccumulatedInInvestments	234	458
Available for sale, Gross Unrealized Depreciation	(149)	(36)
Available for sale, Fair Value	10,379	10,473
Available for sale, OTTI recognized in AOCI	(36)	(84)
Held to maturity, Amortized Cost	1,440	2,028
States, Municipalities, And Political Subdivisions [Member]
Investment [Line Items]
Held to maturity, Gross Unrealized Appreciation	19	44
Held to maturity, Gross Unrealized Depreciation	(15)	(4)
Held to maturity, Fair Value	1,192	1,195
Held to maturity, OTTI recognized in AOCI	0	0
Available for sale, Amortized Cost	3,295	2,517
AvailableforsaleSecuritiesGrossUnrealizedGainAccumulatedInInvestments	72	163
Available for sale, Gross Unrealized Depreciation	(63)	(3)
Available for sale, Fair Value	3,304	2,677
Available for sale, OTTI recognized in AOCI	0	0
Held to maturity, Amortized Cost	$ 1,188	$ 1,155