Investments (Net Investment Income And Investment Gains (Losses)) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Total investment income	$ 740		$ 676
Investment expenses	(14)		(15)
Net investment income	726		661
Investment gains (a)	32	[1]	23	[1]
Net unrealized gains on trading securities	36		21
Gross realized gains on available-for-sale securities	72		93
Gross realized losses on available-for-sale securities	41		73
Fixed Maturity Securities [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Total investment income	516		506
Investment gains (a)	30		20
Short Term Investments [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Total investment income	3		3
Investment gains (a)			2
Limited Partnerships [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Total investment income	143		134
Equity Securities [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Total investment income	4		6
Investment gains (a)	1
Income From Trading Portfolio [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Total investment income	70	[2]	23	[2]
Other Investment Income [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Total investment income	4		4
Investment gains (a)	2		2
Derivative Instruments [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment gains (a)	$ (1)		$ (1)

[1] Includes gross realized gains of $72 million and $93 million and gross realized losses of $41 million and $73 million on available-for-sale securities for the three months ended March 31, 2012 and 2011.

[2] Includes net unrealized gains related to changes in fair value on trading securities still held of $36 million and $21 million for the three months ended March 31, 2012 and 2011.