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	Dec. 31, 2012	Dec. 31, 2011
Investment [Line Items]
Available for sale, Amortized Cost	$ 44,666	$ 40,450
Available for sale, Gross Unrealized Appreciation	2,725	1,927
Available for sale, Gross Unrealized Depreciation	(85)	(410)
Available for sale, Fair Value	47,306	41,967
Available for sale, OTTI recognized in AOCI	(91)	(175)
Held to maturity, Amortized Cost	7,270	8,447
Held to maturity, Gross Unrealized Appreciation	367	232
Held to maturity, Gross Unrealized Depreciation	(4)	(74)
Held to maturity, Fair Value	7,633	8,605
Held to maturity, OTTI recognized in AOCI
U.S. Treasury and agency
Investment [Line Items]
Available for sale, Amortized Cost	3,553	2,774
Available for sale, Gross Unrealized Appreciation	183	186
Available for sale, Gross Unrealized Depreciation	(1)	0
Available for sale, Fair Value	3,735	2,960
Available for sale, OTTI recognized in AOCI	0	0
Held to maturity, Amortized Cost	1,044	1,078
Held to maturity, Gross Unrealized Appreciation	39	48
Held to maturity, Gross Unrealized Depreciation	0	0
Held to maturity, Fair Value	1,083	1,126
Held to maturity, OTTI recognized in AOCI	0	0
Foreign
Investment [Line Items]
Available for sale, Amortized Cost	13,016	12,025
Available for sale, Gross Unrealized Appreciation	711	475
Available for sale, Gross Unrealized Depreciation	(14)	(99)
Available for sale, Fair Value	13,713	12,401
Available for sale, OTTI recognized in AOCI	0	(2)
Held to maturity, Amortized Cost	910	935
Held to maturity, Gross Unrealized Appreciation	54	18
Held to maturity, Gross Unrealized Depreciation	0	(23)
Held to maturity, Fair Value	964	930
Held to maturity, OTTI recognized in AOCI	0	0
Corporate securities
Investment [Line Items]
Available for sale, Amortized Cost	15,529	14,055
Available for sale, Gross Unrealized Appreciation	1,210	773
Available for sale, Gross Unrealized Depreciation	(31)	(135)
Available for sale, Fair Value	16,708	14,693
Available for sale, OTTI recognized in AOCI	(7)	(22)
Held to maturity, Amortized Cost	2,133	2,338
Held to maturity, Gross Unrealized Appreciation	142	44
Held to maturity, Gross Unrealized Depreciation	0	(45)
Held to maturity, Fair Value	2,275	2,337
Held to maturity, OTTI recognized in AOCI	0	0
Mortgage backed-securities
Investment [Line Items]
Available for sale, Amortized Cost	10,051	9,979
Available for sale, Gross Unrealized Appreciation	458	397
Available for sale, Gross Unrealized Depreciation	(36)	(175)
Available for sale, Fair Value	10,473	10,201
Available for sale, OTTI recognized in AOCI	(84)	(151)
Held to maturity, Amortized Cost	2,028	2,949
Held to maturity, Gross Unrealized Appreciation	88	90
Held to maturity, Gross Unrealized Depreciation	0	(3)
Held to maturity, Fair Value	2,116	3,036
Held to maturity, OTTI recognized in AOCI	0	0
States, municipalities, and political subdivisions
Investment [Line Items]
Available for sale, Amortized Cost	2,517	1,617
Available for sale, Gross Unrealized Appreciation	163	96
Available for sale, Gross Unrealized Depreciation	(3)	(1)
Available for sale, Fair Value	2,677	1,712
Available for sale, OTTI recognized in AOCI	0	0
Held to maturity, Amortized Cost	1,155	1,147
Held to maturity, Gross Unrealized Appreciation	44	32
Held to maturity, Gross Unrealized Depreciation	(4)	(3)
Held to maturity, Fair Value	1,195	1,176
Held to maturity, OTTI recognized in AOCI	$ 0	$ 0