Derivatives - Cash Flow Hedges (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Realized Investment Gains (Losses)	$ 395	$ (112)	$ 165
Net investment income	1,951	1,780	1,603
Interest Expense	259	298	316
Interest rate swaps | Reclassification out of Accumulated Other Comprehensive Income | Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Net investment income	4	30	37
Interest Expense	1	0	0
Foreign currency swaps | Reclassification out of Accumulated Other Comprehensive Income | Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Net investment income	3	0	0
Designated as Hedging Instrument | Cash Flow Hedging
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain (Loss) Recognized in OCI on Derivative	26	12	(6)
Designated as Hedging Instrument | Cash Flow Hedging | Reclassification out of Accumulated Other Comprehensive Income | Interest rate swaps
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain Reclassified from AOCI into Income	2	6	5
Designated as Hedging Instrument | Cash Flow Hedging | Reclassification out of Accumulated Other Comprehensive Income | Foreign currency swaps
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain Reclassified from AOCI into Income	7	30	37
Designated as Hedging Instrument | Cash Flow Hedging | Reclassification out of Accumulated Other Comprehensive Income | Interest Expense [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain Reclassified from AOCI into Income	1	0	0
Designated as Hedging Instrument | Cash Flow Hedging | Interest rate swaps
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain (Loss) Recognized in OCI on Derivative	18	5	8
Designated as Hedging Instrument | Cash Flow Hedging | Interest rate swaps | Reclassification out of Accumulated Other Comprehensive Income | Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent | Interest rate swaps
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain Reclassified from AOCI into Income	2	6	5
Designated as Hedging Instrument | Cash Flow Hedging | Interest rate swaps | Reclassification out of Accumulated Other Comprehensive Income | Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent | Foreign currency swaps
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain Reclassified from AOCI into Income	4	30	37
Designated as Hedging Instrument | Cash Flow Hedging | Interest rate swaps | Reclassification out of Accumulated Other Comprehensive Income | Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent | Interest Expense [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain Reclassified from AOCI into Income	1	0	0
Designated as Hedging Instrument | Cash Flow Hedging | Foreign currency swaps
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain (Loss) Recognized in OCI on Derivative	8	7	(14)
Designated as Hedging Instrument | Cash Flow Hedging | Foreign currency swaps | Reclassification out of Accumulated Other Comprehensive Income | Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent | Interest rate swaps
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain Reclassified from AOCI into Income	0	0	0
Designated as Hedging Instrument | Cash Flow Hedging | Foreign currency swaps | Reclassification out of Accumulated Other Comprehensive Income | Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent | Foreign currency swaps
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain Reclassified from AOCI into Income	3	0	0
Designated as Hedging Instrument | Cash Flow Hedging | Foreign currency swaps | Reclassification out of Accumulated Other Comprehensive Income | Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent | Interest Expense [Member]
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Gain Reclassified from AOCI into Income	$ 0	$ 0	$ 0