Investments and Derivative Instruments Level 4 Variable Interest Entities (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	$ 55	$ 157
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities	11	22
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	44	139
Fixed Income Funds [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	53	154
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities	10	20
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	43	138
Limited Partnerships and Other Alternative Investments [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities	1	2
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	$ 1	$ 1