Reinsurance Level 4 Reinsurance Revenues (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Assumed Premiums Earned	$ 129	$ 113	$ 74
Ceded Premiums Earned	(1,616)	(1,801)	(2,060)
Life Annuity Accident and Health Insurance Product Line [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Gross Fee Income Earned Premium and Other Life	2,659	2,877	3,228
Assumed Premiums Earned	129	113	74
Ceded Premiums Earned	(1,616)	(1,801)	(2,060)
Net Fee Income Earned Premium and Other Life	1,172	1,189	$ 1,242
Investment Contracts [Member] | Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Reinsurance Premiums for Insurance Companies, by Product Segment [Line Items]
Financial Liabilities Fair Value Disclosure	$ 526	$ 682