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, 2012	Dec. 31, 2011
Investment [Line Items]
Held to maturity, Gross Unrealized Appreciation	$ 391	$ 232
Held to maturity, Gross Unrealized Depreciation	(5)	(74)
Held to maturity, Fair Value	7,879	8,605
Held to maturity, OTTI recognized in AOCI
Available for sale, Amortized Cost	43,758	40,450
Available for sale, Gross Unrealized Appreciation	2,843	1,927
Available for sale, Gross Unrealized Depreciation	(97)	(410)
Available for sale, Fair Value	46,504	41,967
Available for sale, OTTI recognized in AOCI	(101)	(175)
Held to maturity, Amortized Cost	7,493	8,447
U.S. Treasury And Agency [Member]
Investment [Line Items]
Held to maturity, Gross Unrealized Appreciation	45	48
Held to maturity, Fair Value	1,129	1,126
Held to maturity, OTTI recognized in AOCI	0	0
Available for sale, Amortized Cost	3,357	2,774
Available for sale, Gross Unrealized Appreciation	197	186
Available for sale, Fair Value	3,554	2,960
Available for sale, OTTI recognized in AOCI	0	0
Held to maturity, Amortized Cost	1,084	1,078
Foreign [Member]
Investment [Line Items]
Held to maturity, Gross Unrealized Appreciation	52	18
Held to maturity, Gross Unrealized Depreciation	(1)	(23)
Held to maturity, Fair Value	970	930
Held to maturity, OTTI recognized in AOCI	0	0
Available for sale, Amortized Cost	13,241	12,025
Available for sale, Gross Unrealized Appreciation	750	475
Available for sale, Gross Unrealized Depreciation	(24)	(99)
Available for sale, Fair Value	13,967	12,401
Available for sale, OTTI recognized in AOCI	(1)	(2)
Held to maturity, Amortized Cost	919	935
Corporate Securities [Member]
Investment [Line Items]
Held to maturity, Gross Unrealized Appreciation	140	44
Held to maturity, Gross Unrealized Depreciation	0	(45)
Held to maturity, Fair Value	2,322	2,337
Held to maturity, OTTI recognized in AOCI	0	0
Available for sale, Amortized Cost	14,677	14,055
Available for sale, Gross Unrealized Appreciation	1,192	773
Available for sale, Gross Unrealized Depreciation	(36)	(135)
Available for sale, Fair Value	15,833	14,693
Available for sale, OTTI recognized in AOCI	(12)	(22)
Held to maturity, Amortized Cost	2,182	2,338
Mortgage Backed-Securities [Member]
Investment [Line Items]
Held to maturity, Gross Unrealized Appreciation	108	90
Held to maturity, Gross Unrealized Depreciation	0	(3)
Held to maturity, Fair Value	2,330	3,036
Held to maturity, OTTI recognized in AOCI	0	0
Available for sale, Amortized Cost	10,227	9,979
Available for sale, Gross Unrealized Appreciation	545	397
Available for sale, Gross Unrealized Depreciation	(36)	(175)
Available for sale, Fair Value	10,736	10,201
Available for sale, OTTI recognized in AOCI	(88)	(151)
Held to maturity, Amortized Cost	2,222	2,949
States, Municipalities, And Political Subdivisions [Member]
Investment [Line Items]
Held to maturity, Gross Unrealized Appreciation	46	32
Held to maturity, Gross Unrealized Depreciation	(4)	(3)
Held to maturity, Fair Value	1,128	1,176
Held to maturity, OTTI recognized in AOCI	0	0
Available for sale, Amortized Cost	2,256	1,617
Available for sale, Gross Unrealized Appreciation	159	96
Available for sale, Gross Unrealized Depreciation	(1)	(1)
Available for sale, Fair Value	2,414	1,712
Available for sale, OTTI recognized in AOCI	0	0
Held to maturity, Amortized Cost	$ 1,086	$ 1,147