Investments and Derivative Instruments (Details 17) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Derivative Instruments Gain (Loss) [Line Items]
Document Period End Date	Mar. 31, 2013
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	$ 6	[1]	$ 11	[1]
Gain or (Loss) Recognized in Income, Hedged Item	(8)		(10)	[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	(2)	[1]	9	[1]
Gain or (Loss) Recognized in Income, Hedged Item	2	[1]	(9)	[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	(1)	[1]	(3)	[1]
Gain or (Loss) Recognized in Income, Hedged Item	$ 1	[1]	$ 3	[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