Investments (Net Investment Income And Investment Gains (Losses)) (Details) (USD $) In Millions	3 Months Ended				9 Months Ended
	Sep. 30, 2011		Sep. 30, 2010		Sep. 30, 2011		Sep. 30, 2010
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Total investment income	$ 348		$ 668		$ 1,558		$ 1,838
Investment expenses	(15)		(14)		(45)		(41)
Net investment income	333		654		1,513		1,797
Investment gains (losses)	(27)	[1]	62	[1]	15	[1]	94	[1]
Net unrealized gains (losses) on trading securities			55				52
Gross realized gains on available-for-sale securities	57		124		240		359
Gross realized losses on available-for-sale securities	87		65		232		232
Short Term Investments [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Total investment income	4		4		11		18
Investment gains (losses)			1		3		5
Fixed Maturity Securities [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Total investment income	494		511		1,505		1,540
Investment gains (losses)	(29)		76		11		169
Income (Loss) From Trading Portfolio [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Total investment income	(70)	[2]	52	[2]	(55)	[2]	68	[2]
Limited Partnerships [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Total investment income	(87)		91		69		178
Equity Securities [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Total investment income	4		7		16		26
Investment gains (losses)	(1)		(17)		(3)		(42)
Other Investment Income [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Total investment income	3		3		12		8
Investment gains (losses)	2		3		4		(6)
Derivative Instruments [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment gains (losses)	$ 1		$ (1)				$ (32)

[1] Includes gross realized gains of $57, $124, $240 and $359 and gross realized losses of $87, $65, $232 and $232 on available-for-sale securities for the three and nine months ended September 30, 2011 and 2010.

[2] Includes net unrealized gains/(losses) related to changes in fair value on trading securities still held of $(63), $55, $(86) and $52 for the three and nine months ended September 30, 2011 and 2010.