Investments (Aggregate Fair Value And Gross Unrealized Loss By Length Of Time Security Has Continuously Been In Unrealized Loss Position) (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Investment [Line Items]
Investment securities, Unrealized loss position, 0-12 Months, Fair Value	$ 14,040	$ 18,228
Investment securities, Unrealized loss position, 0-12 Months, Gross Unrealized Loss	(383)	(652)
Investment securities, Unrealized loss position, Over 12 Months, Fair Value	1,090	894
Investment securities, Unrealized loss position, Over 12 Months, Gross Unrealized Loss	(62)	(63)
Investment securities, Unrealized loss position, Total Fair Value	15,130	19,122
Investment securities, Unrealized loss position, Total Gross Unrealized Loss	(445)	(715)
US Treasury and Government [Member]
Investment [Line Items]
Investment securities, Unrealized loss position, 0-12 Months, Fair Value	1,609	1,794
Investment securities, Unrealized loss position, 0-12 Months, Gross Unrealized Loss	(37)	(57)
Investment securities, Unrealized loss position, Over 12 Months, Fair Value	33	31
Investment securities, Unrealized loss position, Over 12 Months, Gross Unrealized Loss	(4)	(6)
Investment securities, Unrealized loss position, Total Fair Value	1,642	1,825
Investment securities, Unrealized loss position, Total Gross Unrealized Loss	(41)	(63)
Foreign Government Debt Securities [Member]
Investment [Line Items]
Investment securities, Unrealized loss position, 0-12 Months, Fair Value	2,988	4,621
Investment securities, Unrealized loss position, 0-12 Months, Gross Unrealized Loss	(56)	(114)
Investment securities, Unrealized loss position, Over 12 Months, Fair Value	259	201
Investment securities, Unrealized loss position, Over 12 Months, Gross Unrealized Loss	(9)	(8)
Investment securities, Unrealized loss position, Total Fair Value	3,247	4,822
Investment securities, Unrealized loss position, Total Gross Unrealized Loss	(65)	(122)
Corporate Securities [Member]
Investment [Line Items]
Investment securities, Unrealized loss position, 0-12 Months, Fair Value	2,940	3,836
Investment securities, Unrealized loss position, 0-12 Months, Gross Unrealized Loss	(58)	(118)
Investment securities, Unrealized loss position, Over 12 Months, Fair Value	211	194
Investment securities, Unrealized loss position, Over 12 Months, Gross Unrealized Loss	(13)	(14)
Investment securities, Unrealized loss position, Total Fair Value	3,151	4,030
Investment securities, Unrealized loss position, Total Gross Unrealized Loss	(71)	(132)
Collateralized Mortgage Backed Securities [Member]
Investment [Line Items]
Investment securities, Unrealized loss position, 0-12 Months, Fair Value	4,367	5,248
Investment securities, Unrealized loss position, 0-12 Months, Gross Unrealized Loss	(130)	(197)
Investment securities, Unrealized loss position, Over 12 Months, Fair Value	398	384
Investment securities, Unrealized loss position, Over 12 Months, Gross Unrealized Loss	(25)	(31)
Investment securities, Unrealized loss position, Total Fair Value	4,765	5,632
Investment securities, Unrealized loss position, Total Gross Unrealized Loss	(155)	(228)
US States and Political Subdivisions Debt Securities [Member]
Investment [Line Items]
Investment securities, Unrealized loss position, 0-12 Months, Fair Value	1,575	2,164
Investment securities, Unrealized loss position, 0-12 Months, Gross Unrealized Loss	(39)	(90)
Investment securities, Unrealized loss position, Over 12 Months, Fair Value	189	84
Investment securities, Unrealized loss position, Over 12 Months, Gross Unrealized Loss	(11)	(4)
Investment securities, Unrealized loss position, Total Fair Value	1,764	2,248
Investment securities, Unrealized loss position, Total Gross Unrealized Loss	(50)	(94)
Fixed Maturities [Member]
Investment [Line Items]
Investment securities, Unrealized loss position, 0-12 Months, Fair Value	13,479	17,663
Investment securities, Unrealized loss position, 0-12 Months, Gross Unrealized Loss	(320)	(576)
Investment securities, Unrealized loss position, Over 12 Months, Fair Value	1,090	894
Investment securities, Unrealized loss position, Over 12 Months, Gross Unrealized Loss	(62)	(63)
Investment securities, Unrealized loss position, Total Fair Value	14,569	18,557
Investment securities, Unrealized loss position, Total Gross Unrealized Loss	(382)	(639)
Equity Securities [Member]
Investment [Line Items]
Investment securities, Unrealized loss position, 0-12 Months, Fair Value	496	498
Investment securities, Unrealized loss position, 0-12 Months, Gross Unrealized Loss	(58)	(67)
Investment securities, Unrealized loss position, Over 12 Months, Fair Value	0	0
Investment securities, Unrealized loss position, Over 12 Months, Gross Unrealized Loss	0	0
Investment securities, Unrealized loss position, Total Fair Value	496	498
Investment securities, Unrealized loss position, Total Gross Unrealized Loss	(58)	(67)
Other Long-term Investments [Member]
Investment [Line Items]
Investment securities, Unrealized loss position, 0-12 Months, Fair Value	65	67
Investment securities, Unrealized loss position, 0-12 Months, Gross Unrealized Loss	(5)	(9)
Investment securities, Unrealized loss position, Over 12 Months, Fair Value	0	0
Investment securities, Unrealized loss position, Over 12 Months, Gross Unrealized Loss	0	0
Investment securities, Unrealized loss position, Total Fair Value	65	67
Investment securities, Unrealized loss position, Total Gross Unrealized Loss	$ (5)	$ (9)