Derivative Instruments Level 4 Credit Risk Assumed through Credit Derivatives (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Credit Derivatives [Line Items]
Derivative, Notional Amount	$ 38,579		$ 38,579		$ 41,099
Credit Default Swap, Selling Protection [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	723		723		961
Credit Risk Derivatives, at Fair Value, Net	(3)		(3)		92
Credit Derivatives in Offsetting Positions [Member] | Credit Default Swap, Selling Protection [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	324		324		503
Credit Risk Derivatives, at Fair Value, Net	7		7		11
Credit Derivatives in Offsetting Positions [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					45
Credit Derivatives in Offsetting Positions [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	15		15
Credit Derivatives in Offsetting Positions [Member] | Credit Default Swap, Selling Protection [Member] | Debt Securities Payable [Member] | Standard & Poor's, CCC+ Rating [Member] | External Credit Rating, Non Investment Grade [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	43		43		43
Derivative, Fair Value, Amount Offset Against Collateral, Net	0		0		0
Credit Derivatives in Offsetting Positions [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	169		169		225
Derivative, Fair Value, Amount Offset Against Collateral, Net	(1)		(1)		(1)
Credit Derivatives in Offsetting Positions [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	22		22
Derivative, Fair Value, Amount Offset Against Collateral, Net	0		0
Credit Derivatives in Offsetting Positions [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					22
Derivative, Fair Value, Amount Offset Against Collateral, Net					(2)
Credit Derivatives in Offsetting Positions [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					0
Derivative, Fair Value, Amount Offset Against Collateral, Net					0
Credit Derivatives in Offsetting Positions [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	46		46
Derivative, Fair Value, Amount Offset Against Collateral, Net	7		7
Credit Derivatives in Offsetting Positions [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	29		29		111
Derivative, Fair Value, Amount Offset Against Collateral, Net	1		1		1
Credit Derivatives in Offsetting Positions [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					57
Derivative, Fair Value, Amount Offset Against Collateral, Net					13
Credit Derivatives in Offsetting Positions [Member] | Single Name Credit Default Swaps [Member] | Debt Securities Payable [Member] | Standard & Poor's, A Rating [Member] | External Credit Rating, Investment Grade [Member]
Credit Derivatives [Line Items]
Derivative, Fair Value, Amount Offset Against Collateral, Net					0
Credit Derivatives in Offsetting Positions [Member] | Single Name Credit Default Swaps [Member] | Debt Securities Payable [Member] | Standard & Poor's, A Rating [Member] | External Credit Rating, Investment Grade [Member]
Credit Derivatives [Line Items]
Derivative, Fair Value, Amount Offset Against Collateral, Net	0		0
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					100
Credit Risk Derivatives, at Fair Value, Net					$ 100
Average Term of Credit Risk Derivatives					1 year
Basket Credit Default Swaps [Member]
Credit Derivatives [Line Items]
Amount of Standard Market Indices of Diversified Portfolios of Corporate Issuers	1,800		1,800		$ 1,800
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	419		419		493
Credit Risk Derivatives, at Fair Value, Net	1		$ 1		$ 5
Average Term of Credit Risk Derivatives			3 years		3 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	22		$ 22
Credit Risk Derivatives, at Fair Value, Net	2		$ 2
Average Term of Credit Risk Derivatives			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					$ 22
Credit Risk Derivatives, at Fair Value, Net					$ 2
Average Term of Credit Risk Derivatives					4 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	46		$ 46
Credit Risk Derivatives, at Fair Value, Net	(7)		(7)
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	76		76		$ 158
Credit Risk Derivatives, at Fair Value, Net	(1)		$ (1)		$ (2)
Average Term of Credit Risk Derivatives			4 years		2 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					$ 57
Credit Risk Derivatives, at Fair Value, Net					$ (13)
Average Term of Credit Risk Derivatives					1 year
Single Name Credit Default Swaps [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					$ 88
Credit Risk Derivatives, at Fair Value, Net					$ 0
Average Term of Credit Risk Derivatives					3 years
Single Name Credit Default Swaps [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	117		$ 117
Credit Risk Derivatives, at Fair Value, Net	2		$ 2
Average Term of Credit Risk Derivatives			4 years
Single Name Credit Default Swaps [Member] | Credit Default Swap, Selling Protection [Member] | Debt Securities Payable [Member] | Standard & Poor's, CCC+ Rating [Member] | External Credit Rating, Non Investment Grade [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	43		$ 43		$ 43
Credit Risk Derivatives, at Fair Value, Net	0		$ 0		$ 0
Average Term of Credit Risk Derivatives			1 year		1 year
Not Designated as Hedging Instrument [Member]
Credit Derivatives [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(32)	$ 22	$ (81)	$ 19
Derivative, Notional Amount	36,745		36,745		$ 39,141
Not Designated as Hedging Instrument [Member] | Credit Default Swap, Selling Protection [Member]
Credit Derivatives [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(16)	3	(9)	1
Not Designated as Hedging Instrument [Member] | Other Credit Derivatives [Member]
Credit Derivatives [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(5)	(23)	(3)	(29)
Not Designated as Hedging Instrument [Member] | Foreign Exchange Forward [Member]
Credit Derivatives [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(9)	62	8	96
Not Designated as Hedging Instrument [Member] | Credit Derivatives in Offsetting Positions [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	648		648		$ 1,006
Not Designated as Hedging Instrument [Member] | Currency Swap [Member] | Foreign Exchange Forward [Member]
Credit Derivatives [Line Items]
Derivative, Gain (Loss) on Derivative, Net	$ 1	$ 2	$ (3)	$ 0