Investments and Derivative Instruments (Details 4) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013		Dec. 31, 2012
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	$ 17,046		$ 4,981
Less Than 12 Months, Fair Value	16,309		4,855
Less Than 12 Months, Unrealized Losses	(737)		(126)
12 Months or More, Amortized Cost	6,326		7,850
12 Months or More, Fair Value	5,731		6,894
12 Months or More, Unrealized Losses	(585)		(936)
Amortized Cost	23,372		12,831
Fair Value	22,040		11,749
Unrealized Losses	(1,322)		(1,062)
ABS [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	984		163
Less Than 12 Months, Fair Value	979		161
Less Than 12 Months, Unrealized Losses	(5)		(2)
12 Months or More, Amortized Cost	631		886
12 Months or More, Fair Value	521		705
12 Months or More, Unrealized Losses	(110)		(181)
Amortized Cost	1,615		1,049
Fair Value	1,500		866
Unrealized Losses	(115)		(183)
Collateralized Debt Obligations [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	75	[1]	5	[1]
Less Than 12 Months, Fair Value	74	[1]	4	[1]
Less Than 12 Months, Unrealized Losses	(1)	[1]	(1)	[1]
12 Months or More, Amortized Cost	2,371	[1]	2,567	[1]
12 Months or More, Fair Value	2,266	[1]	2,389	[1]
12 Months or More, Unrealized Losses	(95)	[1]	(158)	[1]
Amortized Cost	2,446	[1]	2,572	[1]
Fair Value	2,340	[1]	2,393	[1]
Unrealized Losses	(96)	[1]	(159)	[1]
CMBS [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	640		339
Less Than 12 Months, Fair Value	614		322
Less Than 12 Months, Unrealized Losses	(26)		(17)
12 Months or More, Amortized Cost	871		1,248
12 Months or More, Fair Value	788		1,086
12 Months or More, Unrealized Losses	(83)		(162)
Amortized Cost	1,511		1,587
Fair Value	1,402		1,408
Unrealized Losses	(109)		(179)
Corporate [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	6,026		1,261
Less Than 12 Months, Fair Value	5,757		1,218
Less Than 12 Months, Unrealized Losses	(269)		(43)
12 Months or More, Amortized Cost	1,372		1,823
12 Months or More, Fair Value	1,195		1,590
12 Months or More, Unrealized Losses	(177)		(233)
Amortized Cost	7,398		3,084
Fair Value	6,952		2,808
Unrealized Losses	(446)		(276)
Foreign Government Debt Securities [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	2,376		1,380
Less Than 12 Months, Fair Value	2,197		1,343
Less Than 12 Months, Unrealized Losses	(179)		(37)
12 Months or More, Amortized Cost	11		20
12 Months or More, Fair Value	9		17
12 Months or More, Unrealized Losses	(2)		(3)
Amortized Cost	2,387		1,400
Fair Value	2,206		1,360
Unrealized Losses	(181)		(40)
Municipal [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	2,048		271
Less Than 12 Months, Fair Value	1,933		265
Less Than 12 Months, Unrealized Losses	(115)		(6)
12 Months or More, Amortized Cost	98		157
12 Months or More, Fair Value	85		144
12 Months or More, Unrealized Losses	(13)		(13)
Amortized Cost	2,146		428
Fair Value	2,018		409
Unrealized Losses	(128)		(19)
RMBS [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	1,856		910
Less Than 12 Months, Fair Value	1,802		908
Less Than 12 Months, Unrealized Losses	(54)		(2)
12 Months or More, Amortized Cost	731		869
12 Months or More, Fair Value	667		738
12 Months or More, Unrealized Losses	(64)		(131)
Amortized Cost	2,587		1,779
Fair Value	2,469		1,646
Unrealized Losses	(118)		(133)
U.S. Treasuries [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	2,850		583
Less Than 12 Months, Fair Value	2,768		567
Less Than 12 Months, Unrealized Losses	(82)		(16)
12 Months or More, Amortized Cost	0		0
12 Months or More, Fair Value	0		0
12 Months or More, Unrealized Losses	0		0
Amortized Cost	2,850		583
Fair Value	2,768		567
Unrealized Losses	(82)		(16)
Fixed maturities [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	16,855		4,912
Less Than 12 Months, Fair Value	16,124		4,788
Less Than 12 Months, Unrealized Losses	(731)		(124)
12 Months or More, Amortized Cost	6,085		7,570
12 Months or More, Fair Value	5,531		6,669
12 Months or More, Unrealized Losses	(544)		(881)
Amortized Cost	22,940		12,482
Fair Value	21,655		11,457
Unrealized Losses	(1,275)		(1,005)
Equity Securities [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	191		69
Less Than 12 Months, Fair Value	185		67
Less Than 12 Months, Unrealized Losses	(6)		(2)
12 Months or More, Amortized Cost	241		280
12 Months or More, Fair Value	200		225
12 Months or More, Unrealized Losses	(41)		(55)
Amortized Cost	432		349
Fair Value	385		292
Unrealized Losses	$ (47)		$ (57)

[1] Unrealized losses exclude the change in fair value of bifurcated embedded derivative features of certain securities. Changes in fair value are recorded in net realized capital gains (losses).