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	3 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Investment [Line Items]
Document Period End Date	Mar. 31, 2015
Held to maturity, Amortized Cost	$ 6,982	$ 7,331
Held to maturity, Gross Unrealized Appreciation	327	266
Held to maturity, Gross Unrealized Depreciation	(2)	(8)
Held to maturity, Fair Value	7,307	7,589
Available for sale, Amortized Cost	48,384	47,826
AvailableforsaleSecuritiesGrossUnrealizedGainAccumulatedInInvestments	2,215	1,871
Available for sale, Gross Unrealized Depreciation	(189)	(302)
Available for sale, Fair Value	50,410	49,395
Available for sale, OTTI recognized in AOCI	(7)	(8)
U.S. Treasury And Agency [Member]
Investment [Line Items]
Held to maturity, Amortized Cost	756	832
Held to maturity, Gross Unrealized Appreciation	24	20
Held to maturity, Gross Unrealized Depreciation	0	(2)
Held to maturity, Fair Value	780	850
Held to maturity, OTTI recognized in AOCI	0	0
Available for sale, Amortized Cost	2,793	2,741
AvailableforsaleSecuritiesGrossUnrealizedGainAccumulatedInInvestments	98	87
Available for sale, Gross Unrealized Depreciation	(2)	(8)
Available for sale, Fair Value	2,889	2,820
Available for sale, OTTI recognized in AOCI	0	0
Foreign [Member]
Investment [Line Items]
Held to maturity, Amortized Cost	816	916
Held to maturity, Gross Unrealized Appreciation	57	47
Held to maturity, Gross Unrealized Depreciation	0	0
Held to maturity, Fair Value	873	963
Held to maturity, OTTI recognized in AOCI	0	0
Available for sale, Amortized Cost	14,262	14,703
AvailableforsaleSecuritiesGrossUnrealizedGainAccumulatedInInvestments	761	629
Available for sale, Gross Unrealized Depreciation	(76)	(90)
Available for sale, Fair Value	14,947	15,242
Available for sale, OTTI recognized in AOCI	0	0
Corporate Securities [Member]
Investment [Line Items]
Held to maturity, Amortized Cost	2,249	2,323
Held to maturity, Gross Unrealized Appreciation	122	102
Held to maturity, Gross Unrealized Depreciation	0	(2)
Held to maturity, Fair Value	2,371	2,423
Held to maturity, OTTI recognized in AOCI	0	0
Available for sale, Amortized Cost	17,259	16,897
AvailableforsaleSecuritiesGrossUnrealizedGainAccumulatedInInvestments	834	704
Available for sale, Gross Unrealized Depreciation	(94)	(170)
Available for sale, Fair Value	17,999	17,431
Available for sale, OTTI recognized in AOCI	(6)	(7)
Mortgage Backed-Securities [Member]
Investment [Line Items]
Held to maturity, Amortized Cost	1,907	1,983
Held to maturity, Gross Unrealized Appreciation	77	57
Held to maturity, Gross Unrealized Depreciation	(1)	(1)
Held to maturity, Fair Value	1,983	2,039
Held to maturity, OTTI recognized in AOCI	0	0
Available for sale, Amortized Cost	10,459	10,011
AvailableforsaleSecuritiesGrossUnrealizedGainAccumulatedInInvestments	362	304
Available for sale, Gross Unrealized Depreciation	(13)	(29)
Available for sale, Fair Value	10,808	10,286
Available for sale, OTTI recognized in AOCI	(1)	(1)
States, Municipalities, And Political Subdivisions [Member]
Investment [Line Items]
Held to maturity, Amortized Cost	1,254	1,277
Held to maturity, Gross Unrealized Appreciation	47	40
Held to maturity, Gross Unrealized Depreciation	(1)	(3)
Held to maturity, Fair Value	1,300	1,314
Held to maturity, OTTI recognized in AOCI	0	0
Available for sale, Amortized Cost	3,611	3,474
AvailableforsaleSecuritiesGrossUnrealizedGainAccumulatedInInvestments	160	147
Available for sale, Gross Unrealized Depreciation	(4)	(5)
Available for sale, Fair Value	3,767	3,616
Available for sale, OTTI recognized in AOCI	$ 0	$ 0