- Quantitative Information - Assets (Details) - Income Approach Valuation Technique [Member] - Level 3 [Member] - USD ($)		12 Months Ended
		Dec. 31, 2015		Dec. 31, 2014
Obligations of state and political subdivisions [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset, fair value		$ 7,000,000		$ 38,000,000	[1]
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%
Cash flow receipts (as a percent)				0.50%
Discount factor (as a percent)				4.60%
Collateral recovery period (in years)				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%
Cash flow receipts (as a percent)				74.30%
Discount factor (as a percent)				8.00%
Collateral recovery period (in years)				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%
Cash flow receipts (as a percent)				63.00%
Discount factor (as a percent)				7.30%
Collateral recovery period (in years)				28 years
Corporate securities [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset, fair value		$ 71,000,000	[2],[3],[4]	$ 79,000,000	[1]
Yield (as a percent)		21.80%	[3],[4]	17.80%
Residential Mortgage-Backed Securities (RMBS) [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset, fair value		$ 348,000,000	[2],[3],[4]	$ 425,000,000	[1]
Residential Mortgage-Backed Securities (RMBS) [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield (as a percent)		4.70%	[3],[4]	4.70%
Conditional prepayment rate (as a percent)		0.30%	[3],[4]	0.30%
Conditional default rate (as a percent)		2.70%	[3],[4]	2.70%
Loss severity rate (as a percent)		60.00%	[3],[4]	52.60%
Residential Mortgage-Backed Securities (RMBS) [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield (as a percent)		8.20%	[3],[4]	11.70%
Conditional prepayment rate (as a percent)		9.00%	[3],[4]	8.10%
Conditional default rate (as a percent)		9.30%	[3],[4]	10.60%
Loss severity rate (as a percent)		100.00%	[3],[4]	100.00%
Residential Mortgage-Backed Securities (RMBS) [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield (as a percent)		6.00%	[3],[4]	6.40%
Conditional prepayment rate (as a percent)		2.60%	[3],[4]	3.30%
Conditional default rate (as a percent)		7.00%	[3],[4]	5.30%
Loss severity rate (as a percent)		74.00%	[3],[4]	75.20%
Investor-owned utilities [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset, fair value		$ 69,000,000	[2],[3],[4]	$ 95,000,000	[1]
Cash flow receipts (as a percent)	[3],[4]			100.00%
Discount factor (as a percent)		7.00%	[3],[4]	7.00%
Collateral recovery period (in years)	[3],[4]	2 years 10 months 24 days
Investor-owned utilities [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Collateral recovery period (in years)				4 years
Liquidation value				$ 1
XXX life insurance transactions [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset, fair value		$ 329,000,000	[2],[3],[4]	$ 133,000,000	[1]
Yield (as a percent)				7.30%
XXX life insurance transactions [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield (as a percent)	[3],[4]	3.50%
XXX life insurance transactions [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield (as a percent)	[3],[4]	7.50%
XXX life insurance transactions [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield (as a percent)	[3],[4]	5.00%
Pooled corporate obligations [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset, fair value	[2],[3],[4]	$ 259,000,000
Discount factor (as a percent)	[3],[4]	20.00%
Short-term Investments [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset, fair value	[2],[4]	$ 60,000,000
Yield (as a percent)	[4]	17.00%
Other invested assets [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset, fair value		$ 8,000,000		$ 7,000,000	[1]
Other invested assets [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Conditional prepayment rate (as a percent)				5.00%
Conditional default rate (as a percent)				0.00%
Loss severity rate (as a percent)				40.00%
Liquidity discount (as a percent)				20.00%
Recovery on delinquent loans (as a percent)				40.00%
Other invested assets [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Conditional prepayment rate (as a percent)				15.00%
Conditional default rate (as a percent)				7.00%
Loss severity rate (as a percent)				75.00%
Other invested assets [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Conditional prepayment rate (as a percent)				12.30%
Conditional default rate (as a percent)				5.80%
Loss severity rate (as a percent)				68.30%
Financial Guaranty Variable Interest Entities [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset, fair value		$ 1,261,000,000	[2],[4]	$ 1,398,000,000	[1]
Financial Guaranty Variable Interest Entities [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield (as a percent)		1.90%	[4]	2.70%
Conditional prepayment rate (as a percent)		0.30%	[4]	0.30%
Conditional default rate (as a percent)		1.20%	[4]	1.60%
Loss severity rate (as a percent)		40.00%	[4]	40.00%
Financial Guaranty Variable Interest Entities [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Yield (as a percent)		20.00%	[4]	17.70%
Conditional prepayment rate (as a percent)		9.20%	[4]	11.00%
Conditional default rate (as a percent)		16.00%	[4]	11.80%
Loss severity rate (as a percent)		100.00%	[4]	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%	[4]	7.90%
Conditional prepayment rate (as a percent)		3.90%	[4]	3.30%
Conditional default rate (as a percent)		4.70%	[4]	5.10%
Loss severity rate (as a percent)		85.90%	[4]	82.20%
Other Assets [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Asset, fair value		$ 62,000,000	[2],[4]	$ 35,000,000
Fair Value Inputs Term		5 years	[4]	5 years
Other Assets [Member] | Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Quotes from third party pricing (in dollars per share)		$ 44	[4]	$ 52
Other Assets [Member] | Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Quotes from third party pricing (in dollars per share)		46	[4]	61
Other Assets [Member] | Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Quotes from third party pricing (in dollars per share)		$ 45	[4]	$ 57

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

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

[3] Excludes obligations of state and political subdivisions investments with fair value of $8 million.

[4] Excludes several investments recorded in other invested assets with fair value of $7 million.