Investments and Derivative Instruments (Details 5) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	$ 7,261	$ 1,986
Less Than 12 Months, Fair Value	6,888	1,892
Less Than 12 Months, Unrealized Losses	(373)	(94)
12 Months or More, Amortized Cost	4,371	5,588
12 Months or More, Fair Value	3,913	4,851
12 Months or More, Unrealized Losses	(456)	(729)
Amortized Cost	11,632	7,574
Fair Value	10,801	6,743
Unrealized Losses	(829)	(823)
ABS [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	226	77
Less Than 12 Months, Fair Value	223	76
Less Than 12 Months, Unrealized Losses	(3)	(1)
12 Months or More, Amortized Cost	561	787
12 Months or More, Fair Value	464	616
12 Months or More, Unrealized Losses	(97)	(171)
Amortized Cost	787	864
Fair Value	687	692
Unrealized Losses	(100)	(172)
Collateralized Debt Obligations [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	101	5
Less Than 12 Months, Fair Value	100	5
Less Than 12 Months, Unrealized Losses	(1)	0
12 Months or More, Amortized Cost	1,383	1,640
12 Months or More, Fair Value	1,315	1,515
12 Months or More, Unrealized Losses	(66)	(117)
Amortized Cost	1,484	1,645
Fair Value	1,415	1,520
Unrealized Losses	(67)	(117)
CMBS [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	291	192
Less Than 12 Months, Fair Value	278	179
Less Than 12 Months, Unrealized Losses	(13)	(13)
12 Months or More, Amortized Cost	495	795
12 Months or More, Fair Value	458	701
12 Months or More, Unrealized Losses	(37)	(94)
Amortized Cost	786	987
Fair Value	736	880
Unrealized Losses	(50)	(107)
Corporate [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	2,791	614
Less Than 12 Months, Fair Value	2,658	578
Less Than 12 Months, Unrealized Losses	(133)	(36)
12 Months or More, Amortized Cost	990	1,339
12 Months or More, Fair Value	853	1,154
12 Months or More, Unrealized Losses	(137)	(185)
Amortized Cost	3,781	1,953
Fair Value	3,511	1,732
Unrealized Losses	(270)	(221)
Foreign Government Debt Securities [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	874	318
Less Than 12 Months, Fair Value	763	290
Less Than 12 Months, Unrealized Losses	(111)	(28)
12 Months or More, Amortized Cost	10	7
12 Months or More, Fair Value	8	6
12 Months or More, Unrealized Losses	(2)	(1)
Amortized Cost	884	325
Fair Value	771	296
Unrealized Losses	(113)	(29)
Municipal [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	569	65
Less Than 12 Months, Fair Value	531	62
Less Than 12 Months, Unrealized Losses	(38)	(3)
12 Months or More, Amortized Cost	110	98
12 Months or More, Fair Value	102	87
12 Months or More, Unrealized Losses	(8)	(11)
Amortized Cost	679	163
Fair Value	633	149
Unrealized Losses	(46)	(14)
RMBS [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	741	322
Less Than 12 Months, Fair Value	718	321
Less Than 12 Months, Unrealized Losses	(23)	(1)
12 Months or More, Amortized Cost	552	750
12 Months or More, Fair Value	502	636
12 Months or More, Unrealized Losses	(50)	(114)
Amortized Cost	1,293	1,072
Fair Value	1,220	957
Unrealized Losses	(73)	(115)
U.S. Treasuries [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	1,593	384
Less Than 12 Months, Fair Value	1,545	372
Less Than 12 Months, Unrealized Losses	(48)	(12)
12 Months or More, Amortized Cost	114	0
12 Months or More, Fair Value	85	0
12 Months or More, Unrealized Losses	(29)	0
Amortized Cost	1,707	384
Fair Value	1,630	372
Unrealized Losses	(77)	(12)
Fixed maturities [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	7,186	1,977
Less Than 12 Months, Fair Value	6,816	1,883
Less Than 12 Months, Unrealized Losses	(370)	(94)
12 Months or More, Amortized Cost	4,215	5,416
12 Months or More, Fair Value	3,787	4,715
12 Months or More, Unrealized Losses	(426)	(693)
Amortized Cost	11,401	7,393
Fair Value	10,603	6,598
Unrealized Losses	(796)	(787)
Equity Securities [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	75	9
Less Than 12 Months, Fair Value	72	9
Less Than 12 Months, Unrealized Losses	(3)	0
12 Months or More, Amortized Cost	156	172
12 Months or More, Fair Value	126	136
12 Months or More, Unrealized Losses	(30)	(36)
Amortized Cost	231	181
Fair Value	198	145
Unrealized Losses	$ (33)	$ (36)