Investments and Derivative Instruments (Details 5) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2012		Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Document Period End Date	Sep. 30, 2012
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	$ 3,418		$ 7,837
Less Than 12 Months, Fair Value	3,285		7,381
Less Than 12 Months, Unrealized Losses	(133)		(456)
12 Months or More, Amortized Cost	9,731		11,613
12 Months or More, Fair Value	8,397		9,324
12 Months or More, Unrealized Losses	(1,295)		(2,218)
Amortized Cost	13,149		19,450
Fair Value	11,682		16,705
Unrealized Losses	(1,428)		(2,674)
ABS [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	12		629
Less Than 12 Months, Fair Value	11		594
Less Than 12 Months, Unrealized Losses	(1)		(35)
12 Months or More, Amortized Cost	1,071		1,169
12 Months or More, Fair Value	845		872
12 Months or More, Unrealized Losses	(226)		(297)
Amortized Cost	1,083		1,798
Fair Value	856		1,466
Unrealized Losses	(227)		(332)
Collateralized Debt Obligations [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	20	[1]	81
Less Than 12 Months, Fair Value	19	[1]	59
Less Than 12 Months, Unrealized Losses	(1)	[1]	(22)
12 Months or More, Amortized Cost	3,169	[1]	2,709
12 Months or More, Fair Value	2,914	[1]	2,383
12 Months or More, Unrealized Losses	(216)	[1]	(326)
Amortized Cost	3,189	[1]	2,790
Fair Value	2,933	[1]	2,442
Unrealized Losses	(217)	[1]	(348)
CMBS [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	232		1,297
Less Than 12 Months, Fair Value	201		1,194
Less Than 12 Months, Unrealized Losses	(31)		(103)
12 Months or More, Amortized Cost	1,575		2,144
12 Months or More, Fair Value	1,362		1,735
12 Months or More, Unrealized Losses	(213)		(409)
Amortized Cost	1,807		3,441
Fair Value	1,563		2,929
Unrealized Losses	(244)		(512)
Corporate [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	1,402		4,388	[1]
Less Than 12 Months, Fair Value	1,332		4,219	[1]
Less Than 12 Months, Unrealized Losses	(70)		(169)	[1]
12 Months or More, Amortized Cost	2,289		3,268	[1]
12 Months or More, Fair Value	1,966		2,627	[1]
12 Months or More, Unrealized Losses	(323)		(570)	[1]
Amortized Cost	3,691		7,656	[1]
Fair Value	3,298		6,846	[1]
Unrealized Losses	(393)		(739)	[1]
Foreign Government Debt Securities [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	272		218
Less Than 12 Months, Fair Value	270		212
Less Than 12 Months, Unrealized Losses	(2)		(6)
12 Months or More, Amortized Cost	19		51
12 Months or More, Fair Value	16		47
12 Months or More, Unrealized Losses	(3)		(4)
Amortized Cost	291		269
Fair Value	286		259
Unrealized Losses	(5)		(10)
Municipal [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	135		299
Less Than 12 Months, Fair Value	131		294
Less Than 12 Months, Unrealized Losses	(4)		(5)
12 Months or More, Amortized Cost	183		627
12 Months or More, Fair Value	167		560
12 Months or More, Unrealized Losses	(16)		(67)
Amortized Cost	318		926
Fair Value	298		854
Unrealized Losses	(20)		(72)
RMBS [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	148		415
Less Than 12 Months, Fair Value	146		330
Less Than 12 Months, Unrealized Losses	(2)		(85)
12 Months or More, Amortized Cost	1,147		1,206
12 Months or More, Fair Value	907		835
12 Months or More, Unrealized Losses	(240)		(371)
Amortized Cost	1,295		1,621
Fair Value	1,053		1,165
Unrealized Losses	(242)		(456)
U.S. Treasuries [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	1,085		343
Less Than 12 Months, Fair Value	1,069		341
Less Than 12 Months, Unrealized Losses	(16)		(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	1,085		343
Fair Value	1,069		341
Unrealized Losses	(16)		(2)
Fixed maturities [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	3,306		7,670
Less Than 12 Months, Fair Value	3,179		7,243
Less Than 12 Months, Unrealized Losses	(127)		(427)
12 Months or More, Amortized Cost	9,453		11,174
12 Months or More, Fair Value	8,177		9,059
12 Months or More, Unrealized Losses	(1,237)		(2,044)
Amortized Cost	12,759		18,844
Fair Value	11,356		16,302
Unrealized Losses	(1,364)		(2,471)
Equity Securities [Member]
Security Unrealized Loss Aging
Less Than 12 Months, Amortized Cost	112		167
Less Than 12 Months, Fair Value	106		138
Less Than 12 Months, Unrealized Losses	(6)		(29)
12 Months or More, Amortized Cost	278		439
12 Months or More, Fair Value	220		265
12 Months or More, Unrealized Losses	(58)		(174)
Amortized Cost	390		606
Fair Value	326		403
Unrealized Losses	$ (64)		$ (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).