Investments and Derivative Instruments Level 4 Credit Derivatives (Details) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2015		Dec. 31, 2014
Credit Derivatives [Line Items]
Derivative, Notional Amount	$ 71,313,000,000		$ 72,850,000,000
Derivative, Fair Value, Net	(555,000,000)		(639,000,000)
Credit [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	4,438,000,000	[1],[2]	4,159,000,000	[1],[2]
Derivative, Fair Value, Net	359,000,000	[2]	345,000,000	[2]
Offsetting Notional Amount	2,575,000,000	[2],[3]	2,672,000,000	[2],[3]
Derivative, Fair Value, Amount Offset Against Collateral, Net	(5,000,000)	[2],[3]	(5,000,000)	[2],[3]
Basket Credit Default Swaps [Member]
Credit Derivatives Footnote [Abstract]
Amount of Standard Market Indices of Diversified Portfolios of Corporate Issuers	3,800,000,000		3,500,000,000
CMBS Credit [Member] | Basket Credit Default Swaps [Member] | Below Investment Grade Risk Exposure [Member] | Credit [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	154,000,000	[1]	154,000,000	[1]
Derivative, Fair Value, Net	(22,000,000)		(22,000,000)
Derivative, Average Remaining Maturity	2 years		2 years
Underlying Referenced Credit Obligation Type	CMBS Credit	[2]	CMBS Credit	[2]
Average Credit Rating	CCC+	[2]	CCC+	[2]
Offsetting Notional Amount	154,000,000	[3]	154,000,000	[3]
Derivative, Fair Value, Amount Offset Against Collateral, Net	21,000,000	[3]	23,000,000	[3]
CMBS Credit [Member] | Basket Credit Default Swaps [Member] | Investment Grade Risk Exposure [Member] | Credit [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	873,000,000	[1]	38,000,000	[1]
Derivative, Fair Value, Net	(12,000,000)		(1,000,000)
Derivative, Average Remaining Maturity	6 years		12 years
Underlying Referenced Credit Obligation Type	CMBS Credit	[2]	CMBS Credit	[2]
Average Credit Rating	AA+	[2]	D	[2]
Offsetting Notional Amount	267,000,000	[3]	269,000,000	[3]
Derivative, Fair Value, Amount Offset Against Collateral, Net	2,000,000	[3]	3,000,000	[3]
Corporate Credit [Member] | Embedded Credit Derivatives [Member] | Investment Grade Risk Exposure [Member] | Credit [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	350,000,000	[1]	350,000,000	[1]
Derivative, Fair Value, Net	347,000,000		342,000,000
Derivative, Average Remaining Maturity	2 years		2 years
Underlying Referenced Credit Obligation Type	Corporate Credit	[2]	Corporate Credit	[2]
Average Credit Rating	A+	[2]	A	[2]
Offsetting Notional Amount	0	[3]	0	[3]
Derivative, Fair Value, Amount Offset Against Collateral, Net	0	[3]	0	[3]
Corporate Credit [Member] | Basket Credit Default Swaps [Member] | Below Investment Grade Risk Exposure [Member] | Credit [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	59,000,000	[1],[2],[4]	722,000,000	[1]
Derivative, Fair Value, Net	4,000,000	[2],[4]	(12,000,000)
Derivative, Average Remaining Maturity	5 years	[2],[4]	6 years
Underlying Referenced Credit Obligation Type	Corporate Credit	[2]	Corporate Credit	[2]
Average Credit Rating	B+	[2]	AA+	[2]
Offsetting Notional Amount	0	[3]	0	[3]
Derivative, Fair Value, Amount Offset Against Collateral, Net	0	[3]	0	[3]
Corporate Credit [Member] | Basket Credit Default Swaps [Member] | Investment Grade Risk Exposure [Member] | Credit [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	2,721,000,000	[1]	2,546,000,000	[1]
Derivative, Fair Value, Net	38,000,000		33,000,000
Derivative, Average Remaining Maturity	3 years		3 years
Underlying Referenced Credit Obligation Type	Corporate Credit	[2]	Corporate Credit	[2]
Average Credit Rating	BBB+	[2]	BBB	[2]
Offsetting Notional Amount	1,898,000,000	[3]	1,973,000,000	[3]
Derivative, Fair Value, Amount Offset Against Collateral, Net	(23,000,000)	[3]	(25,000,000)	[3]
Corporate Credit [Member] | Single Name Credit Default Swaps [Member] | Below Investment Grade Risk Exposure [Member] | Credit [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	29,000,000	[1]	29,000,000	[1]
Derivative, Fair Value, Net	0		0
Derivative, Average Remaining Maturity	2 years		2 years
Underlying Referenced Credit Obligation Type	Corporate Credit		Corporate Credit	[2]
Average Credit Rating	BB		BB	[2]
Offsetting Notional Amount	29,000,000	[3]	29,000,000	[3]
Derivative, Fair Value, Amount Offset Against Collateral, Net	(1,000,000)	[3]	(1,000,000)	[3]
Corporate Credit of Foreign Government [Member] | Single Name Credit Default Swaps [Member] | Investment Grade Risk Exposure [Member] | Credit [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	252,000,000	[1]	320,000,000	[1]
Derivative, Fair Value, Net	4,000,000		5,000,000
Derivative, Average Remaining Maturity	2 years		2 years
Underlying Referenced Credit Obligation Type	Corporate Credit/ Foreign Gov.		Corporate Credit/ Foreign Gov.	[2]
Average Credit Rating	BBB+		BBB+	[2]
Offsetting Notional Amount	227,000,000	[3]	247,000,000	[3]
Derivative, Fair Value, Amount Offset Against Collateral, Net	$ (4,000,000)	[3]	$ (5,000,000)	[3]

[1] Notional amount is equal to the maximum potential future loss amount. These derivatives are governed by agreements, clearing house rules and applicable law which include collateral posting requirements. There is no additional specific collateral related to these contracts or recourse provisions included in the contracts to offset losses.

[2] The average credit ratings are based on availability and the midpoint of the applicable ratings among Moody’s, S&P, Fitch and Morningstar. If no rating is available from a rating agency, then an internally developed rating is used.

[3] The Company has entered into offsetting credit default swaps to terminate certain existing credit default swaps, thereby offsetting the future changes in value of, or losses paid related to, the original swap.

[4] Includes $3.8 billion and $3.5 billion as of March 31, 2015 and December 31, 2014, respectively, of standard market indices of diversified portfolios of corporate and CMBS issuers referenced through credit default swaps. These swaps are subsequently valued based upon the observable standard market index.