Fair Value (Quantitative Information) (Details)	Mar. 31, 2021	Dec. 31, 2020
Minimum | Interest rate contracts | Measurement Input, Swap Yield
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative Asset (Liability) Net, Measurement Input	173	92
Minimum | Interest rate contracts | Measurement Input, Repurchase Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative Asset (Liability) Net, Measurement Input	1	(12)
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	(307)	(309)
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	0.18	0.21
Minimum | Equity market contracts | Measurement Input, Correlation
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative Asset (Liability) Net, Measurement Input	0.30	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	0.0841	0.0833
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	0.0005	0.0004
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	0.0012	0.0012
Minimum | U.S. corporate and foreign corporate | 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	0
Minimum | U.S. corporate and foreign corporate | 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 | U.S. corporate and foreign corporate | 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	53	54
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	1
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	101	100
Maximum | Interest rate contracts | Measurement Input, Swap Yield
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative Asset (Liability) Net, Measurement Input	265	184
Maximum | Interest rate contracts | Measurement Input, Repurchase Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative Asset (Liability) Net, Measurement Input	20	1
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	1,938	248
Maximum | Credit contracts | Measurement Input, Credit Spread
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative Asset (Liability) Net, Measurement Input	99	99
Maximum | Equity market contracts | Measurement Input, Price Volatility
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative Asset (Liability) Net, Measurement Input	0.28	0.29
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	0.27	0.27
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	0.0127	0.0118
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	0.0017	0.0017
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	0.0075	0.0075
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 | Valuation Technique, Matrix Pricing | Measurement Input, Offered Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-sale, Measurement Input	167	186
Maximum | U.S. corporate and foreign corporate | Valuation Technique, Market Approach | Measurement Input, Quoted Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-sale, Measurement Input	125	116
Maximum | U.S. corporate and foreign corporate | 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	103	104
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	129	159
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	112	112
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	101	100
Weighted Average | Interest rate contracts | Measurement Input, Swap Yield
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative Asset (Liability) Net, Measurement Input	240	149
Weighted Average | Interest rate contracts | Measurement Input, Repurchase Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative Asset (Liability) Net, Measurement Input	11	(6)
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	(52)	(144)
Weighted Average | Credit contracts | Measurement Input, Credit Spread
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative Asset (Liability) Net, Measurement Input	98	98
Weighted Average | Equity market contracts | Measurement Input, Price Volatility
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative Asset (Liability) Net, Measurement Input	0.27	0.28
Weighted Average | Equity market contracts | Measurement Input, Correlation
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative Asset (Liability) Net, Measurement Input	0.30	0.10
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	0.0017	0.0017
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	0.0398	0.0398
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	0.1870	0.1870
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	0.0040	0.0040
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	0.0686	0.0686
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	0.0518	0.0518
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	0.0518	0.0518
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	0.0006	0.0006
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	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	0.0190
Weighted Average | U.S. corporate and foreign corporate | Valuation Technique, Matrix Pricing | Measurement Input, Offered Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-sale, Measurement Input	110	117
Weighted Average | U.S. corporate and foreign corporate | Valuation Technique, Market Approach | Measurement Input, Quoted Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Debt Securities, Available-for-sale, Measurement Input	98	98
Weighted Average | U.S. corporate and foreign corporate | 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	101
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	98	98
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	100	100
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	101	100