Fair Value (Quantitative Information) (Details) - $ / shares	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Embedded derivatives direct, assumed, and ceded guaranteed minimum benefits | Minimum | Income Approach Valuation Technique
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Utilization rates	0.00%	0.00%
Withdrawal rates	0.25%	0.25%
Long-term equity volatilities	17.40%	17.40%
Nonperformance risk spread	0.04%	0.04%
Embedded derivatives direct, assumed, and ceded guaranteed minimum benefits | Minimum | Income Approach Valuation Technique | Withdrawal rates
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Lapse Rate	0.25%	0.25%
Embedded derivatives direct, assumed, and ceded guaranteed minimum benefits | Minimum | Income Approach Valuation Technique | Long-term equity volatilities
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Lapse Rate	2.00%	2.00%
Embedded derivatives direct, assumed, and ceded guaranteed minimum benefits | Minimum | Income Approach Valuation Technique | Nonperformance risk spread
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Lapse Rate	2.00%	2.00%
Embedded derivatives direct, assumed, and ceded guaranteed minimum benefits | Minimum | Income Approach Valuation Technique | Durations 1 - 10
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Mortality Rate	0.00%	0.00%
Embedded derivatives direct, assumed, and ceded guaranteed minimum benefits | Minimum | Income Approach Valuation Technique | Durations 11 - 20
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Mortality Rate	0.04%	0.04%
Embedded derivatives direct, assumed, and ceded guaranteed minimum benefits | Minimum | Income Approach Valuation Technique | Durations 21 - 116
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Mortality Rate	0.26%	0.26%
Embedded derivatives direct, assumed, and ceded guaranteed minimum benefits | Maximum | Income Approach Valuation Technique
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Utilization rates	25.00%	25.00%
Withdrawal rates	10.00%	10.00%
Long-term equity volatilities	25.00%	25.00%
Nonperformance risk spread	0.55%	0.57%
Embedded derivatives direct, assumed, and ceded guaranteed minimum benefits | Maximum | Income Approach Valuation Technique | Withdrawal rates
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Lapse Rate	100.00%	100.00%
Embedded derivatives direct, assumed, and ceded guaranteed minimum benefits | Maximum | Income Approach Valuation Technique | Long-term equity volatilities
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Lapse Rate	100.00%	100.00%
Embedded derivatives direct, assumed, and ceded guaranteed minimum benefits | Maximum | Income Approach Valuation Technique | Nonperformance risk spread
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Lapse Rate	100.00%	100.00%
Embedded derivatives direct, assumed, and ceded guaranteed minimum benefits | Maximum | Income Approach Valuation Technique | Durations 1 - 10
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Mortality Rate	0.09%	0.09%
Embedded derivatives direct, assumed, and ceded guaranteed minimum benefits | Maximum | Income Approach Valuation Technique | Durations 11 - 20
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Mortality Rate	0.65%	0.65%
Embedded derivatives direct, assumed, and ceded guaranteed minimum benefits | Maximum | Income Approach Valuation Technique | Durations 21 - 116
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Mortality Rate	100.00%	100.00%
U.S. corporate and foreign corporate securities | Minimum | Market Approach Valuation Technique
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Offered Quotes Matrix Pricing	$ 96	$ 94
Quoted prices	75	75
U.S. corporate and foreign corporate securities | Maximum | Market Approach Valuation Technique
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Offered Quotes Matrix Pricing	144	136
Quoted prices	110	110
U.S. corporate and foreign corporate securities | Weighted Average | Market Approach Valuation Technique
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair Value Inputs, Offered Quotes Matrix Pricing	107	107
Quoted prices	97	97
CMBS | Minimum | Market Approach Valuation Technique
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Quoted prices		104
CMBS | Maximum | Market Approach Valuation Technique
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Quoted prices		104
CMBS | Weighted Average | Market Approach Valuation Technique
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Quoted prices		104
RMBS | Minimum | Market Approach Valuation Technique
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Quoted prices	58	56
RMBS | Maximum | Market Approach Valuation Technique
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Quoted prices	110	111
RMBS | Weighted Average | Market Approach Valuation Technique
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Quoted prices	$ 79	$ 86