Investments and Derivative Instruments Level 4 Credit Derivatives (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Credit Derivatives [Line Items]
Derivative, Notional Amount	$ 72,850,000,000	$ 159,441,000,000
Derivative, Fair Value, Net	(639,000,000)	(737,000,000)
Basket Credit Default Swaps [Member]
Credit Derivatives [Line Items]
Amount of Standard Market Indices of Diversified Portfolios of Corporate Issuers	3,500,000,000	4,100,000,000
Credit [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	4,159,000,000	5,768,000,000
Derivative, Fair Value, Net	345,000,000	374,000,000
Offsetting Notional Amount	2,672,000,000	3,882,000,000
Derivative, Fair Value, Amount Offset Against Collateral, Net	(5,000,000)	(7,000,000)
Investment Grade Risk Exposure [Member] | Credit [Member] | Single Name Credit Default Swaps [Member] | Corporate Credit of Foreign Government [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	320,000,000	1,259,000,000
Derivative, Fair Value, Net	5,000,000	8,000,000
Derivative, Average Remaining Maturity	2 years	1 year
Underlying Referenced Credit Obligation Type	Corporate Credit/ Foreign Gov.	Corporate Credit/ Foreign Gov.
Average Credit Rating	BBB+	A
Offsetting Notional Amount	247,000,000	1,066,000,000
Derivative, Fair Value, Amount Offset Against Collateral, Net	(5,000,000)	(9,000,000)
Investment Grade Risk Exposure [Member] | Credit [Member] | Basket Credit Default Swaps [Member] | Corporate Credit [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	2,546,000,000	3,447,000,000
Derivative, Fair Value, Net	33,000,000	50,000,000
Derivative, Average Remaining Maturity	3 years	3 years
Underlying Referenced Credit Obligation Type	Corporate Credit	Corporate Credit
Average Credit Rating	BBB	BBB
Offsetting Notional Amount	1,973,000,000	2,270,000,000
Derivative, Fair Value, Amount Offset Against Collateral, Net	(25,000,000)	(35,000,000)
Investment Grade Risk Exposure [Member] | Credit [Member] | Basket Credit Default Swaps [Member] | CMBS Credit [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	722,000,000	166,000,000
Derivative, Fair Value, Net	(12,000,000)	15,000,000
Derivative, Average Remaining Maturity	6 years	5 years
Underlying Referenced Credit Obligation Type	CMBS Credit	CMBS Credit
Average Credit Rating	AA+	BB-
Offsetting Notional Amount	269,000,000	327,000,000
Derivative, Fair Value, Amount Offset Against Collateral, Net	3,000,000	7,000,000
Investment Grade Risk Exposure [Member] | Credit [Member] | Embedded Credit Derivatives [Member] | Corporate Credit [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	350,000,000	350,000,000
Derivative, Fair Value, Net	342,000,000	339,000,000
Derivative, Average Remaining Maturity	2 years	3 years
Underlying Referenced Credit Obligation Type	Corporate Credit	Corporate Credit
Average Credit Rating	A	BBB+
Offsetting Notional Amount	0	0
Derivative, Fair Value, Amount Offset Against Collateral, Net	0	0
Below Investment Grade Risk Exposure [Member] | Credit [Member] | Single Name Credit Default Swaps [Member] | Corporate Credit [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	29,000,000	24,000,000
Derivative, Fair Value, Net	0	0
Derivative, Average Remaining Maturity	2 years	1 year
Underlying Referenced Credit Obligation Type	Corporate Credit	Corporate Credit
Average Credit Rating	BB	CCC
Offsetting Notional Amount	29,000,000	24,000,000
Derivative, Fair Value, Amount Offset Against Collateral, Net	(1,000,000)	(1,000,000)
Below Investment Grade Risk Exposure [Member] | Credit [Member] | Basket Credit Default Swaps [Member] | Corporate Credit [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	38,000,000	327,000,000
Derivative, Fair Value, Net	(1,000,000)	(7,000,000)
Derivative, Average Remaining Maturity	12 years	3 years
Underlying Referenced Credit Obligation Type	Corporate Credit	Corporate Credit
Average Credit Rating	D	A
Offsetting Notional Amount	0	0
Derivative, Fair Value, Amount Offset Against Collateral, Net	0	0
Below Investment Grade Risk Exposure [Member] | Credit [Member] | Basket Credit Default Swaps [Member] | CMBS Credit [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	154,000,000	195,000,000
Derivative, Fair Value, Net	(22,000,000)	(31,000,000)
Derivative, Average Remaining Maturity	2 years	3 years
Underlying Referenced Credit Obligation Type	CMBS Credit	CMBS Credit
Average Credit Rating	CCC+	B-
Offsetting Notional Amount	154,000,000	195,000,000
Derivative, Fair Value, Amount Offset Against Collateral, Net	$ 23,000,000	$ 31,000,000