Investments and Derivative Instruments Level 4 Variable Interest Entities (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	$ 99	$ 157
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities	12	22
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	88	139
Fixed Income Funds [Member] | Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Variable Interest Entity, Consolidated, Carrying Amount, Assets	97	154
Variable Interest Entity, Consolidated, Carrying Amount, Liabilities	11	20
Variable Interest Entity, Reporting Entity Involvement, Maximum Loss Exposure, Amount	87	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