Fair Value (Quantitative information about significant unobservable inputs in the fair value measurement of level 3 assets) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Fixed maturity securities [Member] | Income Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Assets, Fair Value Disclosure	101	142
Fixed maturity securities [Member] | Income Approach Valuation Technique [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Credit Spread	2.00%	2.00%
Fixed maturity securities [Member] | Income Approach Valuation Technique [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Credit Spread	13.00%	20.00%
Fixed maturity securities [Member] | Income Approach Valuation Technique [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Credit Spread	3.00%	4.00%
Equity securities [Member] | Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Assets, Fair Value Disclosure	16	10
Equity securities [Member] | Market Approach Valuation Technique [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Private offering price	12	360
Equity securities [Member] | Market Approach Valuation Technique [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Private offering price	4,391	4,268
Equity securities [Member] | Market Approach Valuation Technique [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Private offering price	600	1,148
Life settlement contracts, included in Other assets [Member] | Income Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Assets, Fair Value Disclosure	82	88
Life settlement contracts, included in Other assets [Member] | Income Approach Valuation Technique [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Mortality assumption	55.00%	70.00%
Life settlement contracts, included in Other assets [Member] | Income Approach Valuation Technique [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Mortality assumption	1676.00%	743.00%
Life settlement contracts, included in Other assets [Member] | Income Approach Valuation Technique [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Mortality assumption	163.00%	192.00%
Life settlement contracts, included in Other assets [Member] | Income Approach Valuation Technique [Member] | Rate [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount rate risk premium	9.00%	9.00%