Fair Value (Quantitative information about significant unobservable inputs in the fair value measurement of level 3 assets) (Details) - Income Approach Valuation Technique [Member] - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Fixed maturity securities [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Assets, Fair Value Disclosure	$ 106	$ 138
Fixed maturity securities [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Credit Spread	2.00%	3.00%
Fixed maturity securities [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Credit Spread	40.00%	184.00%
Fixed maturity securities [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Credit Spread	4.00%	6.00%
Life settlement contracts, included in Other assets [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Assets, Fair Value Disclosure		$ 74
Discount rate risk premium		9.00%
Life settlement contracts, included in Other assets [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Mortality assumption		55.00%
Life settlement contracts, included in Other assets [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Mortality assumption		1676.00%
Life settlement contracts, included in Other assets [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Mortality assumption		164.00%