Fair Value (Quantitative Information) (Details) (USD $)	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
U.S. corporate and foreign corporate securities [Member] | Minimum [Member] | Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Delta spread adjustments	(0.40%)	0.09%
Illiquidity premium	0.30%	0.30%
Matrix Pricing - Offered quotes	$ 99	$ 100
Offered quotes	$ 50	$ 35
Credit spreads	(0.97%)	(1.57%)
U.S. corporate and foreign corporate securities [Member] | Maximum [Member] | Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Delta spread adjustments	2.40%	5.00%
Illiquidity premium	0.30%	0.30%
Matrix Pricing - Offered quotes	$ 100	$ 100
Offered quotes	$ 103	$ 555
Credit spreads	5.35%	8.76%
U.S. corporate and foreign corporate securities [Member] | Weighted Average [Member] | Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Delta spread adjustments	0.70%	1.05%
Illiquidity premium	0.30%	0.30%
Matrix Pricing - Offered quotes	$ 100	$ 100
Offered quotes	$ 86	$ 96
Credit spreads	2.39%	2.82%
RMBS [Member] | Minimum [Member] | Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Quoted prices	$ 84	$ 100
Credit spreads	(1.10%)	0.40%
RMBS [Member] | Maximum [Member] | Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Quoted prices	$ 106	$ 100
Credit spreads	29.84%	23.67%
RMBS [Member] | Weighted Average [Member] | Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Quoted prices	$ 98	$ 100
Credit spreads	2.79%	4.36%
CMBS [Member] | Minimum [Member] | Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Quoted prices	$ 2	$ 100
Offered quotes	$ 100
Credit spreads	0.06%	0.10%
CMBS [Member] | Maximum [Member] | Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Quoted prices	$ 104	$ 104
Offered quotes	$ 100
Credit spreads	14.12%	91.64%
CMBS [Member] | Weighted Average [Member] | Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Quoted prices	$ 97	$ 102
Offered quotes	$ 100
Credit spreads	5.16%	4.13%
ABS [Member] | Minimum [Member] | Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Quoted prices	$ 0	$ 97
Offered quotes	$ 50	$ 50
Credit spreads	0.30%	0.00%
ABS [Member] | Maximum [Member] | Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Quoted prices	$ 104	$ 102
Offered quotes	$ 111	$ 111
Credit spreads	8.75%	9.00%
ABS [Member] | Weighted Average [Member] | Market Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Quoted prices	$ 101	$ 100
Offered quotes	$ 98	$ 100
Credit spreads	2.79%	1.52%
Interest rate contracts [Member] | Minimum [Member] | Income Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Swap yield	2.38%	2.21%
Interest rate contracts [Member] | Maximum [Member] | Income Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Swap yield	4.02%	3.53%
Credit contracts [Member] | Minimum [Member] | Income Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Credit spreads	0.99%	1.00%
Credit contracts [Member] | Maximum [Member] | Income Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Credit spreads	0.99%	1.00%
Equity market contracts [Member] | Minimum [Member] | Present Value techniques or option pricing model [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Volatility	17.00%	18.00%
Equity market contracts [Member] | Maximum [Member] | Present Value techniques or option pricing model [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Volatility	27.00%	26.00%
Embedded derivatives direct and assumed guaranteed benefits [Member] | Minimum [Member] | Income Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Utilization rates	20.00%	20.00%
Withdrawal rates	0.07%	0.07%
Long-term equity volatilities	17.40%	17.40%
Nonperformance risk spread	0.07%	0.10%
Embedded derivatives direct and assumed guaranteed benefits [Member] | Minimum [Member] | Income Approach Valuation Technique [Member] | Durations 1-10 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Lapse rates	0.50%	0.50%
Embedded derivatives direct and assumed guaranteed benefits [Member] | Minimum [Member] | Income Approach Valuation Technique [Member] | Durations 11-20 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Lapse rates	3.00%	3.00%
Embedded derivatives direct and assumed guaranteed benefits [Member] | Minimum [Member] | Income Approach Valuation Technique [Member] | Durations 21-116 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Lapse rates	3.00%	3.00%
Embedded derivatives direct and assumed guaranteed benefits [Member] | Minimum [Member] | Income Approach Valuation Technique [Member] | Ages 0-40 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Mortality rates	0.00%	0.00%
Embedded derivatives direct and assumed guaranteed benefits [Member] | Minimum [Member] | Income Approach Valuation Technique [Member] | Ages 41-60 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Mortality rates	0.05%	0.05%
Embedded derivatives direct and assumed guaranteed benefits [Member] | Minimum [Member] | Income Approach Valuation Technique [Member] | Ages 61-115 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Mortality rates	0.32%	0.32%
Embedded derivatives direct and assumed guaranteed benefits [Member] | Maximum [Member] | Income Approach Valuation Technique [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Utilization rates	50.00%	50.00%
Withdrawal rates	10.00%	10.00%
Long-term equity volatilities	25.00%	25.00%
Nonperformance risk spread	0.61%	0.67%
Embedded derivatives direct and assumed guaranteed benefits [Member] | Maximum [Member] | Income Approach Valuation Technique [Member] | Durations 1-10 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Lapse rates	100.00%	100.00%
Embedded derivatives direct and assumed guaranteed benefits [Member] | Maximum [Member] | Income Approach Valuation Technique [Member] | Durations 11-20 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Lapse rates	100.00%	100.00%
Embedded derivatives direct and assumed guaranteed benefits [Member] | Maximum [Member] | Income Approach Valuation Technique [Member] | Durations 21-116 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Lapse rates	100.00%	100.00%
Embedded derivatives direct and assumed guaranteed benefits [Member] | Maximum [Member] | Income Approach Valuation Technique [Member] | Ages 0-40 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Mortality rates	0.10%	0.10%
Embedded derivatives direct and assumed guaranteed benefits [Member] | Maximum [Member] | Income Approach Valuation Technique [Member] | Ages 41-60 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Mortality rates	0.64%	0.64%
Embedded derivatives direct and assumed guaranteed benefits [Member] | Maximum [Member] | Income Approach Valuation Technique [Member] | Ages 61-115 [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Mortality rates	100.00%	100.00%