- Quantitative Information - Assets (Details) (Income Approach Valuation Technique [Member], Level 3 [Member], USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2015		Dec. 31, 2014
Obligations of state and political subdivisions [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset, fair value	8	[1]	38	[1]
Yield (as a percent)	4.60%
Obligations of state and political subdivisions [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Rate of inflation (as a percent)	1.00%		1.00%
Cash flow receipts (as a percent)	0.50%		0.50%
Yield (as a percent)			4.60%
Collateral recovery period (in years)	4 months		1 month
Obligations of state and political subdivisions [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Rate of inflation (as a percent)	3.00%		3.00%
Cash flow receipts (as a percent)	20.90%		74.30%
Yield (as a percent)			8.00%
Collateral recovery period (in years)	8 years 4 months		34 years
Obligations of state and political subdivisions [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Rate of inflation (as a percent)	2.00%		2.00%
Cash flow receipts (as a percent)	12.90%		63.00%
Yield (as a percent)			7.30%
Collateral recovery period (in years)	4 years 3 months 12 days		28 years
Corporate securities [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset, fair value	79	[1]	79	[1]
Yield (as a percent)	18.00%		17.80%
RMBS [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset, fair value	383	[1]	425	[1]
RMBS [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield (as a percent)	4.20%		4.70%
Conditional prepayment rate (as a percent)	0.30%		0.30%
Conditional default rate (as a percent)	2.40%		2.70%
Loss severity rate (as a percent)	50.00%		52.60%
RMBS [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield (as a percent)	10.00%		11.70%
Conditional prepayment rate (as a percent)	7.50%		8.10%
Conditional default rate (as a percent)	11.60%		10.60%
Loss severity rate (as a percent)	100.00%		100.00%
RMBS [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield (as a percent)	5.90%		6.40%
Conditional prepayment rate (as a percent)	3.40%		3.30%
Conditional default rate (as a percent)	5.50%		5.30%
Loss severity rate (as a percent)	72.40%		75.20%
Investor-owned utilities [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset, fair value	96	[1]	95	[1]
Cash flow receipts (as a percent)	100.00%		100.00%
Discount factor (as a percent)	7.00%		7.00%
Collateral recovery period (in years)	3 years 9 months		4 years
XXX life insurance transactions [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset, fair value	130	[1]	133	[1]
Yield (as a percent)	6.80%		7.30%
Other invested assets [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset, fair value	81	[1]	83	[1]
Liquidity discount (as a percent)	20.00%		20.00%
Recovery on delinquent loans (as a percent)	40.00%		40.00%
Other invested assets [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Conditional prepayment rate (as a percent)	6.00%		5.00%
Conditional default rate (as a percent)	0.00%		0.00%
Loss severity rate (as a percent)	40.00%		40.00%
Net asset value (per share)	966		965
Other invested assets [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Conditional prepayment rate (as a percent)	15.00%		15.00%
Conditional default rate (as a percent)	7.00%		7.00%
Loss severity rate (as a percent)	75.00%		75.00%
Net asset value (per share)	1,147		1,159
Other invested assets [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Conditional prepayment rate (as a percent)	12.00%		12.30%
Conditional default rate (as a percent)	6.10%		5.80%
Loss severity rate (as a percent)	68.70%		68.30%
Net asset value (per share)	1,046		1,082
Financial Guaranty Variable Interest Entities [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset, fair value	1,495	[1]	1,398	[1]
Financial Guaranty Variable Interest Entities [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield (as a percent)	2.70%		2.70%
Conditional prepayment rate (as a percent)	0.30%		0.30%
Conditional default rate (as a percent)	1.70%		1.60%
Loss severity rate (as a percent)	36.00%		40.00%
Financial Guaranty Variable Interest Entities [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield (as a percent)	16.70%		17.70%
Conditional prepayment rate (as a percent)	11.00%		11.00%
Conditional default rate (as a percent)	13.10%		11.80%
Loss severity rate (as a percent)	100.00%		100.00%
Financial Guaranty Variable Interest Entities [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield (as a percent)	6.40%		7.90%
Conditional prepayment rate (as a percent)	2.60%		3.30%
Conditional default rate (as a percent)	4.20%		5.10%
Loss severity rate (as a percent)	64.20%		82.20%
Other Assets [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset, fair value	37	[1]	35	[1]
Fair Value Inputs Term	5 years		5 years
Other Assets [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Quotes from third party pricing (in dollars per share)	51		52
Other Assets [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Quotes from third party pricing (in dollars per share)	60		61
Other Assets [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Quotes from third party pricing (in dollars per share)	56		57

[1] Discounted cash flow is used as valuation technique for all financial instruments.