Derivatives Instruments Level 4 Credit Risk Assumed through Credit Derivatives (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Credit Derivatives [Line Items]
Derivative, Notional Amount	$ 54,221	$ 56,216
Credit Default Swap, Selling Protection [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	3,468	2,968
Credit Risk Derivatives, at Fair Value, Net	191	195
Credit Derivatives in Offsetting Positions [Member] | Credit Default Swap, Selling Protection [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	1,564	1,659
Credit Risk Derivatives, at Fair Value, Net	12	14
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	40	50
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	52
Derivative, Fair Value, Amount Offset Against Collateral, Net	(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	49	77
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, BBB+ Rating [Member] | External Credit Rating, Investment Grade [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	1,204	1,204
Derivative, Fair Value, Amount Offset Against Collateral, Net	(7)	(10)
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		50
Derivative, Fair Value, Amount Offset Against Collateral, Net		(3)
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	0
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, AA+ Rating [Member] | External Credit Rating, Investment Grade [Member]
Credit Derivatives [Line Items]
Derivative, Notional Amount	116	167
Derivative, Fair Value, Amount Offset Against Collateral, Net	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	103	111
Derivative, Fair Value, Amount Offset Against Collateral, Net	19	26
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
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]
Average Term of Credit Risk Derivatives	4 years	4 years
Derivative, Notional Amount	$ 229	$ 169
Credit Risk Derivatives, at Fair Value, Net	$ 2	$ 0
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]
Average Term of Credit Risk Derivatives	1 year
Derivative, Notional Amount	$ 52
Credit Risk Derivatives, at Fair Value, Net	0
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]
Average Term of Credit Risk Derivatives		1 year
Derivative, Notional Amount		$ 77
Credit Risk Derivatives, at Fair Value, Net		0
ERROR in label resolution.
Credit Derivatives [Line Items]
Amount of Standard Market Indices of Diversified Portfolios of Corporate Issuers	$ 3,000	$ 2,500
ERROR in label resolution. | 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]
Average Term of Credit Risk Derivatives	4 years
Derivative, Notional Amount	$ 50
Credit Risk Derivatives, at Fair Value, Net	$ 4
ERROR in label resolution. | 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]
Average Term of Credit Risk Derivatives	3 years	3 years
Derivative, Notional Amount	$ 2,589	$ 2,065
Credit Risk Derivatives, at Fair Value, Net	$ 8	$ 22
ERROR in label resolution. | 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]
Average Term of Credit Risk Derivatives		4 years
Derivative, Notional Amount		$ 50
Credit Risk Derivatives, at Fair Value, Net		$ 3
ERROR in label resolution. | 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]
Average Term of Credit Risk Derivatives	4 years	4 years
Derivative, Notional Amount	$ 246	$ 297
Credit Risk Derivatives, at Fair Value, Net	(4)	$ (5)
ERROR in label resolution. | 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]
Average Term of Credit Risk Derivatives		1 year
Derivative, Notional Amount	102	$ 110
Credit Risk Derivatives, at Fair Value, Net	(19)	(26)
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	200	200
Credit Risk Derivatives, at Fair Value, Net	$ 200	$ 201
Less than 1 year [Member] | ERROR in label resolution. | 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]
Average Term of Credit Risk Derivatives	1 year
Less than 1 year [Member] | Embedded Derivative Financial Instruments [Member] | Other Credit Derivatives [Member] | Debt Securities Payable [Member] | Standard & Poor's, A+ Rating [Member] | External Credit Rating, Investment Grade [Member]
Credit Derivatives [Line Items]
Average Term of Credit Risk Derivatives	1 year	1 year