Investments and Derivative Instruments (Details 17) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2012		Sep. 30, 2011
Derivative Instruments Gain (Loss) [Line Items]
Document Period End Date					Sep. 30, 2012
Fair value hedges [Member]
Derivative Instruments Gain (Loss) [Line Items]
Gain or (Loss) Recognized in Income, Derivative	$ (8)	[1]	$ (87)	[1]	$ (21)	[1]	$ (77)	[1]
Gain or (Loss) Recognized in Income, Hedged Item	7	[1]	87	[1]	18	[1]	77	[1]
Interest Rate Swap [Member] | Net realized capital gains (losses) [Member] | Fair value hedges [Member]
Derivative Instruments Gain (Loss) [Line Items]
Gain or (Loss) Recognized in Income, Derivative	(2)	[1]	(54)	[1]	(7)	[1]	(71)	[1]
Gain or (Loss) Recognized in Income, Hedged Item	1		54	[1]	4	[1]	71	[1]
Foreign Currency Swap [Member] | Net realized capital gains (losses) [Member] | Fair value hedges [Member]
Derivative Instruments Gain (Loss) [Line Items]
Gain or (Loss) Recognized in Income, Derivative	(6)	[1]	(28)	[1]	(8)	[1]	8	[1]
Gain or (Loss) Recognized in Income, Hedged Item	6	[1]	28	[1]	8	[1]	(8)	[1]
Foreign Currency Swap [Member] | Benefits, losses and loss adjustment expenses [Member] | Fair value hedges [Member]
Derivative Instruments Gain (Loss) [Line Items]
Gain or (Loss) Recognized in Income, Derivative	0	[1]	(5)	[1]	(6)	[1]	(14)	[1]
Gain or (Loss) Recognized in Income, Hedged Item	$ 0	[1]	$ 5	[1]	$ 6	[1]	$ 14	[1]

[1] The amounts presented do not include the periodic net coupon settlements of the derivative or the coupon income (expense) related to the hedged item. The net of the amounts presented represents the ineffective portion of the hedge.