Derivative Instruments Level 4 Credit Risk Assumed through Credit Derivatives (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Credit Derivatives [Line Items]
Derivative, Notional Amount	$ 39,644		$ 39,644		$ 41,099
Credit Default Swap, Selling Protection [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	672		672		961
Credit Risk Derivatives, at Fair Value, Net	(2)		(2)		92
Foreign Exchange Forward [Member]
Credit Derivatives [Line Items]
Derivative, Gain (Loss) on Derivative, Net				$ 108
Credit Derivatives in Offsetting Positions [Member] | Credit Default Swap, Selling Protection [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	295		295		503
Credit Risk Derivatives, at Fair Value, Net	6		6		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, B- 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, 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, 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	0		0		(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, AA+ Rating [Member] | External Credit Rating, Investment Grade [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount					111
Derivative, Fair Value, Amount Offset Against Collateral, Net					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	34		34
Derivative, Fair Value, Amount Offset Against Collateral, Net	6		6
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	12		12
Derivative, Fair Value, Amount Offset Against Collateral, Net	0		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					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	1,200		1,200		$ 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	0		$ 0		$ 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, AA+ Rating [Member] | External Credit Rating, Investment Grade [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount					$ 158
Credit Risk Derivatives, at Fair Value, Net					$ (2)
Average Term of Credit Risk Derivatives					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	34		$ 34
Credit Risk Derivatives, at Fair Value, Net	(6)		(6)
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	22		22
Credit Risk Derivatives, at Fair Value, Net	(1)		$ (1)
Average Term of Credit Risk Derivatives			3 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, B- 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
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	132		132
Credit Risk Derivatives, at Fair Value, Net	3		$ 3
Average Term of Credit Risk Derivatives			4 years
Not Designated as Hedging Instrument [Member]
Credit Derivatives [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(58)	$ (47)	$ (139)	(28)
Derivative, Notional Amount	37,810		37,810		$ 39,141
Not Designated as Hedging Instrument [Member] | Credit Default Swap, Selling Protection [Member]
Credit Derivatives [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(1)	9	(10)	10
Not Designated as Hedging Instrument [Member] | Other Credit Derivatives [Member]
Credit Derivatives [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(4)	(1)	(7)	(26)
Not Designated as Hedging Instrument [Member] | Foreign Exchange Forward [Member]
Credit Derivatives [Line Items]
Derivative, Gain (Loss) on Derivative, Net	(4)	12	4	104
Not Designated as Hedging Instrument [Member] | Credit Derivatives in Offsetting Positions [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	590		590		$ 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)	$ (1)	$ (4)	$ (5)