Investments and Derivative Instruments Level 4 Credit Derivatives (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014
Credit Derivatives [Line Items]
Derivative, Notional Amount		$ 46,241	$ 55,838
Derivative, Fair Value, Net		(530)	(460)
Credit Default Swap, Selling Protection [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	[1],[2]		2,034
Credit [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	[1],[2]	2,153
Derivative, Fair Value, Net	[2]	126	148
Derivative, Fair Value, Amount Offset Against Collateral, Net	[2],[3]	12	4
Single Name Credit Default Swaps [Member] | Credit Default Swap, Selling Protection [Member] | Debt Securities Payable [Member] | Standard & Poor's, BBB+ Rating [Member] | External Credit Rating, Investment Grade [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	[1]	118	212
Credit Risk Derivatives, at Fair Value, Net		$ 0	$ 3
Average Term of Credit Risk Derivatives		1 year	3 years
Single Name Credit Default Swaps [Member] | Credit Default Swap, Selling Protection [Member] | Debt Securities Payable [Member] | Standard & Poor's, BB Rating [Member] | External Credit Rating, Non Investment Grade [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	[1]	$ 43	$ 4
Credit Risk Derivatives, at Fair Value, Net		$ (2)	$ 0
Average Term of Credit Risk Derivatives		2 years	1 year
Basket Credit Default Swaps [Member]
Credit Derivatives [Line Items]
Amount of Standard Market Indices of Diversified Portfolios of Corporate Issuers		$ 1,800	$ 1,700
Basket Credit Default Swaps [Member] | Credit Default Swap, Selling Protection [Member] | Debt Securities Payable [Member] | Standard & Poor's, BBB+ Rating [Member] | External Credit Rating, Investment Grade [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	[1],[4]	1,265	1,240
Credit Risk Derivatives, at Fair Value, Net	[4]	$ 7	$ 14
Average Term of Credit Risk Derivatives	[4]	4 years	4 years
Basket Credit Default Swaps [Member] | Credit Default Swap, Selling Protection [Member] | Debt Securities Payable [Member] | Standard & Poor's, B Rating [Member] | External Credit Rating, Non Investment Grade [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	[1],[4]	$ 0	$ 9
Credit Risk Derivatives, at Fair Value, Net	[4]	$ 0	$ (1)
Average Term of Credit Risk Derivatives	[4]		5 years
Basket Credit Default Swaps [Member] | Credit Default Swap, Selling Protection [Member] | Collateralized Mortgage Backed Securities [Member] | Standard & Poor's, CCC+ Rating [Member] | External Credit Rating, Non Investment Grade [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	[1],[4]	$ 74	$ 75
Credit Risk Derivatives, at Fair Value, Net	[4]	$ (13)	$ (11)
Average Term of Credit Risk Derivatives	[4]	1 year	2 years
Basket Credit Default Swaps [Member] | Credit Default Swap, Selling Protection [Member] | Collateralized Mortgage Backed Securities [Member] | Standard & Poor's, AA+ Rating [Member] | External Credit Rating, Investment Grade [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	[1],[4]	$ 503	$ 344
Credit Risk Derivatives, at Fair Value, Net	[4]	$ (14)	$ (4)
Average Term of Credit Risk Derivatives	[4]	6 years	5 years
Embedded Derivative Financial Instruments [Member] | Credit Default Swap, Selling Protection [Member] | Debt Securities Payable [Member] | Standard & Poor's, A+ Rating [Member] | External Credit Rating, Investment Grade [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	[1]	$ 150
Credit Risk Derivatives, at Fair Value, Net		$ 148	$ 147
Average Term of Credit Risk Derivatives		1 year	2 years
Foreign Exchange Contract [Member] | Designated as Hedging Instrument [Member] | Foreign Exchange Contract [Member]
Credit Derivatives [Line Items]
Derivative, Fair Value, Net		$ (19)
Credit Derivatives in Offsetting Positions [Member] | Credit Default Swap, Selling Protection [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	[2],[3]	1,088
Credit Derivatives in Offsetting Positions [Member] | Credit [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	[2],[3]	718
Credit Derivatives in Offsetting Positions [Member] | Single Name Credit Default Swaps [Member] | Credit Default Swap, Selling Protection [Member] | Debt Securities Payable [Member] | Standard & Poor's, BBB+ Rating [Member] | External Credit Rating, Investment Grade [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	[3]	115	$ 163
Credit Risk Derivatives, at Fair Value, Net	[3]	(1)	(3)
Credit Derivatives in Offsetting Positions [Member] | Single Name Credit Default Swaps [Member] | Credit Default Swap, Selling Protection [Member] | Debt Securities Payable [Member] | Standard & Poor's, BB Rating [Member] | External Credit Rating, Non Investment Grade [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	[3]	43	4
Credit Risk Derivatives, at Fair Value, Net	[3]	1	0
Credit Derivatives in Offsetting Positions [Member] | Basket Credit Default Swaps [Member] | Credit Default Swap, Selling Protection [Member] | Debt Securities Payable [Member] | Standard & Poor's, BBB+ Rating [Member] | External Credit Rating, Investment Grade [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	[3],[4]	345	667
Credit Risk Derivatives, at Fair Value, Net	[3],[4]	(2)	(6)
Credit Derivatives in Offsetting Positions [Member] | Basket Credit Default Swaps [Member] | Credit Default Swap, Selling Protection [Member] | Debt Securities Payable [Member] | Standard & Poor's, B Rating [Member] | External Credit Rating, Non Investment Grade [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	[3],[4]	0	0
Credit Risk Derivatives, at Fair Value, Net	[3],[4]	0	0
Credit Derivatives in Offsetting Positions [Member] | Basket Credit Default Swaps [Member] | Credit Default Swap, Selling Protection [Member] | Collateralized Mortgage Backed Securities [Member] | Standard & Poor's, CCC+ Rating [Member] | External Credit Rating, Non Investment Grade [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	[3],[4]	74	75
Credit Risk Derivatives, at Fair Value, Net	[3],[4]	13	11
Credit Derivatives in Offsetting Positions [Member] | Basket Credit Default Swaps [Member] | Credit Default Swap, Selling Protection [Member] | Collateralized Mortgage Backed Securities [Member] | Standard & Poor's, AA+ Rating [Member] | External Credit Rating, Investment Grade [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	[3],[4]	141	179
Credit Risk Derivatives, at Fair Value, Net	[3],[4]	1	2
Credit Derivatives in Offsetting Positions [Member] | Embedded Derivative Financial Instruments [Member] | Credit Default Swap, Selling Protection [Member] | Debt Securities Payable [Member] | Standard & Poor's, A+ Rating [Member] | External Credit Rating, Investment Grade [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	[3]	0	0
Credit Risk Derivatives, at Fair Value, Net	[3]	$ 0	$ 0

[1] [2]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] [5]Excludes investments that contain an embedded credit derivative for which the Company has elected the fair value option. For further discussion, see the Fair Value Option section in Note 2 - Fair Value Measurements.

[3] [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] [4]Includes $1.8 billion and $1.7 billion as of December 31, 2015 and 2014, respectively, of notional amount on swaps 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.