Investments and Derivative Instruments Level 4 Derivative Collateral Arrangements (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2014	Sep. 30, 2015
Derivative Collateral Arrangements [Line Items]
Derivative, Notional Amount	$ 72,850	$ 63,704
Security Owned and Pledged as Collateral, Fair Value	120	298
Fair Value of Securities Received as Collateral that Can be Resold or Repledged	97	131
Securities Received as Collateral, Amount Repledged and Sold	0
Derivative Asset, Collateral, Obligation to Return Cash, Offset	327	433
Derivative, Collateral, Obligation to Return Securities	109	122
Fixed Maturities [Member]
Derivative Collateral Arrangements [Line Items]
Security Owned and Pledged as Collateral, Fair Value	$ 1,100	$ 1,200