Fair Value (Quantitative Information) (Details)	Mar. 31, 2020	Dec. 31, 2019
Minimum | Interest rate contracts | Measurement Input, Swap Yield
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative Asset (Liability) Net, Measurement Input	66	190
Minimum | Interest rate contracts | Measurement Input, Repurchase Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative Asset (Liability) Net, Measurement Input	(18)	(6)
Minimum | Foreign currency exchange rate contracts | Measurement Input, Swap Yield
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative Asset (Liability) Net, Measurement Input	(224)	(125)
Minimum | Credit contracts | Measurement Input, Credit Spread
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative Asset (Liability) Net, Measurement Input	98	96
Minimum | Equity market contracts | Measurement Input, Price Volatility
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative Asset (Liability) Net, Measurement Input	0.21	0.14
Minimum | Equity market contracts | Measurement Input, Correlation
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative Asset (Liability) Net, Measurement Input	0.10	0.10
Minimum | Embedded derivatives direct, assumed and ceded guaranteed minimum benefits | Measurement Input, Utilization Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset (Liability) Net, Measurement Input	0	0
Minimum | Embedded derivatives direct, assumed and ceded guaranteed minimum benefits | Measurement Input, Withdrawal Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset (Liability) Net, Measurement Input	0	0
Minimum | Embedded derivatives direct, assumed and ceded guaranteed minimum benefits | Measurement Input, Long-Term Equity Volatility
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset (Liability) Net, Measurement Input	0.0739	0.0601
Minimum | Embedded derivatives direct, assumed and ceded guaranteed minimum benefits | Measurement Input, Counterparty Credit Risk
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset (Liability) Net, Measurement Input	0.0008	0.0003
Minimum | Embedded derivatives direct, assumed and ceded guaranteed minimum benefits | Durations 1 - 10 | Measurement Input, Lapse Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset (Liability) Net, Measurement Input	0.0025	0.0025
Minimum | Embedded derivatives direct, assumed and ceded guaranteed minimum benefits | Durations 11 - 20 | Measurement Input, Lapse Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset (Liability) Net, Measurement Input	0.0050	0.0050
Minimum | Embedded derivatives direct, assumed and ceded guaranteed minimum benefits | Durations 21 - 116 | Measurement Input, Lapse Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset (Liability) Net, Measurement Input	0.0050	0.0050
Minimum | Embedded derivatives direct, assumed and ceded guaranteed minimum benefits | Ages 0 - 40 | Measurement Input, Mortality Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset (Liability) Net, Measurement Input	0	0
Minimum | Embedded derivatives direct, assumed and ceded guaranteed minimum benefits | Ages 41 - 60 | Measurement Input, Mortality Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset (Liability) Net, Measurement Input	0.0003	0.0003
Minimum | Embedded derivatives direct, assumed and ceded guaranteed minimum benefits | Ages 61 - 115 | Measurement Input, Mortality Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset (Liability) Net, Measurement Input	0.0013	0.0013
Minimum | U.S. corporate and foreign corporate securities | Valuation Technique, Matrix Pricing | Measurement Input, Offered Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-sale, Measurement Input	0	5
Minimum | U.S. corporate and foreign corporate securities | Valuation Technique, Market Approach | Measurement Input, Quoted Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-sale, Measurement Input	20	25
Minimum | U.S. corporate and foreign corporate securities | Valuation Technique, Consensus Pricing Model | Measurement Input, Offered Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-sale, Measurement Input	50	81
Minimum | RMBS | Valuation Technique, Market Approach | Measurement Input, Quoted Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-sale, Measurement Input	0	0
Minimum | ABS | Valuation Technique, Market Approach | Measurement Input, Quoted Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-sale, Measurement Input	3	3
Minimum | ABS | Valuation Technique, Consensus Pricing Model | Measurement Input, Offered Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-sale, Measurement Input	100	99
Maximum | Interest rate contracts | Measurement Input, Swap Yield
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative Asset (Liability) Net, Measurement Input	147	251
Maximum | Interest rate contracts | Measurement Input, Repurchase Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative Asset (Liability) Net, Measurement Input	0	6
Maximum | Foreign currency exchange rate contracts | Measurement Input, Swap Yield
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative Asset (Liability) Net, Measurement Input	328	328
Maximum | Credit contracts | Measurement Input, Credit Spread
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative Asset (Liability) Net, Measurement Input	104	100
Maximum | Equity market contracts | Measurement Input, Price Volatility
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative Asset (Liability) Net, Measurement Input	0.56	0.23
Maximum | Equity market contracts | Measurement Input, Correlation
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative Asset (Liability) Net, Measurement Input	0.30	0.30
Maximum | Embedded derivatives direct, assumed and ceded guaranteed minimum benefits | Measurement Input, Utilization Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset (Liability) Net, Measurement Input	0.22	0.22
Maximum | Embedded derivatives direct, assumed and ceded guaranteed minimum benefits | Measurement Input, Withdrawal Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset (Liability) Net, Measurement Input	0.20	0.20
Maximum | Embedded derivatives direct, assumed and ceded guaranteed minimum benefits | Measurement Input, Long-Term Equity Volatility
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset (Liability) Net, Measurement Input	0.30	0.30
Maximum | Embedded derivatives direct, assumed and ceded guaranteed minimum benefits | Measurement Input, Counterparty Credit Risk
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset (Liability) Net, Measurement Input	0.0169	0.0130
Maximum | Embedded derivatives direct, assumed and ceded guaranteed minimum benefits | Durations 1 - 10 | Measurement Input, Lapse Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset (Liability) Net, Measurement Input	1	1
Maximum | Embedded derivatives direct, assumed and ceded guaranteed minimum benefits | Durations 11 - 20 | Measurement Input, Lapse Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset (Liability) Net, Measurement Input	1	1
Maximum | Embedded derivatives direct, assumed and ceded guaranteed minimum benefits | Durations 21 - 116 | Measurement Input, Lapse Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset (Liability) Net, Measurement Input	1	1
Maximum | Embedded derivatives direct, assumed and ceded guaranteed minimum benefits | Ages 0 - 40 | Measurement Input, Mortality Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset (Liability) Net, Measurement Input	0.0018	0.0018
Maximum | Embedded derivatives direct, assumed and ceded guaranteed minimum benefits | Ages 41 - 60 | Measurement Input, Mortality Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset (Liability) Net, Measurement Input	0.0080	0.0080
Maximum | Embedded derivatives direct, assumed and ceded guaranteed minimum benefits | Ages 61 - 115 | Measurement Input, Mortality Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset (Liability) Net, Measurement Input	1	1
Maximum | U.S. corporate and foreign corporate securities | Valuation Technique, Matrix Pricing | Measurement Input, Offered Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-sale, Measurement Input	191	145
Maximum | U.S. corporate and foreign corporate securities | Valuation Technique, Market Approach | Measurement Input, Quoted Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-sale, Measurement Input	130	131
Maximum | U.S. corporate and foreign corporate securities | Valuation Technique, Consensus Pricing Model | Measurement Input, Offered Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-sale, Measurement Input	108	109
Maximum | RMBS | Valuation Technique, Market Approach | Measurement Input, Quoted Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-sale, Measurement Input	126	119
Maximum | ABS | Valuation Technique, Market Approach | Measurement Input, Quoted Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-sale, Measurement Input	109	119
Maximum | ABS | Valuation Technique, Consensus Pricing Model | Measurement Input, Offered Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-sale, Measurement Input	100	104
Weighted Average | Interest rate contracts | Measurement Input, Swap Yield
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative Asset (Liability) Net, Measurement Input	117
Weighted Average | Interest rate contracts | Measurement Input, Repurchase Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative Asset (Liability) Net, Measurement Input	(10)
Weighted Average | Foreign currency exchange rate contracts | Measurement Input, Swap Yield
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative Asset (Liability) Net, Measurement Input	(131)
Weighted Average | Credit contracts | Measurement Input, Credit Spread
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative Asset (Liability) Net, Measurement Input	100
Weighted Average | Equity market contracts | Measurement Input, Price Volatility
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative Asset (Liability) Net, Measurement Input	0.35
Weighted Average | Equity market contracts | Measurement Input, Correlation
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative Asset (Liability) Net, Measurement Input	0.13
Weighted Average | Embedded derivatives direct, assumed and ceded guaranteed minimum benefits | Measurement Input, Utilization Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset (Liability) Net, Measurement Input	0.0090
Weighted Average | Embedded derivatives direct, assumed and ceded guaranteed minimum benefits | Measurement Input, Withdrawal Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset (Liability) Net, Measurement Input	0.0423
Weighted Average | Embedded derivatives direct, assumed and ceded guaranteed minimum benefits | Measurement Input, Long-Term Equity Volatility
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset (Liability) Net, Measurement Input	0.1830
Weighted Average | Embedded derivatives direct, assumed and ceded guaranteed minimum benefits | Measurement Input, Counterparty Credit Risk
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset (Liability) Net, Measurement Input	0.0049
Weighted Average | Embedded derivatives direct, assumed and ceded guaranteed minimum benefits | Durations 1 - 10 | Measurement Input, Lapse Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset (Liability) Net, Measurement Input	0.0790
Weighted Average | Embedded derivatives direct, assumed and ceded guaranteed minimum benefits | Durations 11 - 20 | Measurement Input, Lapse Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset (Liability) Net, Measurement Input	0.0640
Weighted Average | Embedded derivatives direct, assumed and ceded guaranteed minimum benefits | Durations 21 - 116 | Measurement Input, Lapse Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset (Liability) Net, Measurement Input	0.0640
Weighted Average | Embedded derivatives direct, assumed and ceded guaranteed minimum benefits | Ages 0 - 40 | Measurement Input, Mortality Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset (Liability) Net, Measurement Input	0
Weighted Average | Embedded derivatives direct, assumed and ceded guaranteed minimum benefits | Ages 41 - 60 | Measurement Input, Mortality Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset (Liability) Net, Measurement Input	0.0030
Weighted Average | Embedded derivatives direct, assumed and ceded guaranteed minimum benefits | Ages 61 - 115 | Measurement Input, Mortality Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Embedded Derivative Asset (Liability) Net, Measurement Input	0.0190
Weighted Average | U.S. corporate and foreign corporate securities | Valuation Technique, Matrix Pricing | Measurement Input, Offered Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-sale, Measurement Input	104	110
Weighted Average | U.S. corporate and foreign corporate securities | Valuation Technique, Market Approach | Measurement Input, Quoted Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-sale, Measurement Input	96	100
Weighted Average | U.S. corporate and foreign corporate securities | Valuation Technique, Consensus Pricing Model | Measurement Input, Offered Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-sale, Measurement Input	99	102
Weighted Average | RMBS | Valuation Technique, Market Approach | Measurement Input, Quoted Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-sale, Measurement Input	89	95
Weighted Average | ABS | Valuation Technique, Market Approach | Measurement Input, Quoted Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-sale, Measurement Input	91	98
Weighted Average | ABS | Valuation Technique, Consensus Pricing Model | Measurement Input, Offered Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-sale, Measurement Input	100	100