Investments and Derivative Instruments (Details 5) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012		Dec. 31, 2011
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	$ 6,547		$ 7,837
Less Than 12 Months, Fair Value	6,400		7,381
Less Than 12 Months, Unrealized Losses	(147)		(456)
12 Months or More, Amortized Cost	10,956		11,613
12 Months or More, Fair Value	9,208		9,324
12 Months or More, Unrealized Losses	(1,698)		(2,218)
Amortized Cost	17,503		19,450
Fair Value	15,608		16,705
Unrealized Losses	(1,845)		(2,674)
ABS [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	168		629
Less Than 12 Months, Fair Value	167		594
Less Than 12 Months, Unrealized Losses	(1)		(35)
12 Months or More, Amortized Cost	1,110		1,169
12 Months or More, Fair Value	864		872
12 Months or More, Unrealized Losses	(246)		(297)
Amortized Cost	1,278		1,798
Fair Value	1,031		1,466
Unrealized Losses	(247)		(332)
CDOs [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	3	[1]	81
Less Than 12 Months, Fair Value	2	[1]	59
Less Than 12 Months, Unrealized Losses	(1)	[1]	(22)
12 Months or More, Amortized Cost	3,208	[1]	2,709
12 Months or More, Fair Value	2,891	[1]	2,383
12 Months or More, Unrealized Losses	(267)	[1]	(326)
Amortized Cost	3,211	[1]	2,790
Fair Value	2,893	[1]	2,442
Unrealized Losses	(268)	[1]	(348)
CMBS [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	400		1,297
Less Than 12 Months, Fair Value	366		1,194
Less Than 12 Months, Unrealized Losses	(34)		(103)
12 Months or More, Amortized Cost	2,143		2,144
12 Months or More, Fair Value	1,838		1,735
12 Months or More, Unrealized Losses	(305)		(409)
Amortized Cost	2,543		3,441
Fair Value	2,204		2,929
Unrealized Losses	(339)		(512)
Corporate [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	2,493		4,388	[1]
Less Than 12 Months, Fair Value	2,418		4,219	[1]
Less Than 12 Months, Unrealized Losses	(75)		(169)	[1]
12 Months or More, Amortized Cost	2,576		3,268	[1]
12 Months or More, Fair Value	2,191		2,627	[1]
12 Months or More, Unrealized Losses	(385)		(570)	[1]
Amortized Cost	5,069		7,656	[1]
Fair Value	4,609		6,846	[1]
Unrealized Losses	(460)		(739)	[1]
Foreign govt./govt. agencies [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	557		218
Less Than 12 Months, Fair Value	546		212
Less Than 12 Months, Unrealized Losses	(11)		(6)
12 Months or More, Amortized Cost	30		51
12 Months or More, Fair Value	28		47
12 Months or More, Unrealized Losses	(2)		(4)
Amortized Cost	587		269
Fair Value	574		259
Unrealized Losses	(13)		(10)
Municipal [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	699		299
Less Than 12 Months, Fair Value	689		294
Less Than 12 Months, Unrealized Losses	(10)		(5)
12 Months or More, Amortized Cost	232		627
12 Months or More, Fair Value	199		560
12 Months or More, Unrealized Losses	(33)		(67)
Amortized Cost	931		926
Fair Value	888		854
Unrealized Losses	(43)		(72)
RMBS [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	131		415
Less Than 12 Months, Fair Value	131		330
Less Than 12 Months, Unrealized Losses	0		(85)
12 Months or More, Amortized Cost	1,288		1,206
12 Months or More, Fair Value	902		835
12 Months or More, Unrealized Losses	(386)		(371)
Amortized Cost	1,419		1,621
Fair Value	1,033		1,165
Unrealized Losses	(386)		(456)
U.S. Treasuries [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	1,913		343
Less Than 12 Months, Fair Value	1,903		341
Less Than 12 Months, Unrealized Losses	(10)		(2)
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	1,913		343
Fair Value	1,903		341
Unrealized Losses	(10)		(2)
Fixed maturities [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	6,364		7,670
Less Than 12 Months, Fair Value	6,222		7,243
Less Than 12 Months, Unrealized Losses	(142)		(427)
12 Months or More, Amortized Cost	10,587		11,174
12 Months or More, Fair Value	8,913		9,059
12 Months or More, Unrealized Losses	(1,624)		(2,044)
Amortized Cost	16,951		18,844
Fair Value	15,135		16,302
Unrealized Losses	(1,766)		(2,471)
Equity Securities [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	183		167
Less Than 12 Months, Fair Value	178		138
Less Than 12 Months, Unrealized Losses	(5)		(29)
12 Months or More, Amortized Cost	369		439
12 Months or More, Fair Value	295		265
12 Months or More, Unrealized Losses	(74)		(174)
Amortized Cost	552		606
Fair Value	473		403
Unrealized Losses	$ (79)		$ (203)

[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).