Investments - Investment Income (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	$ 199	$ 50
Investment expenses	(9)	0
Investment Income, Excluding Capital Gains or Losses	190	50
Realized Investment Gains (Losses)	59	0
Net investment income	249	50
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net	(7)	0
Supporting Experience Rated Products [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Net investment income	11	0
Debt Securities [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	156	50
Mortgage Loans [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	17	0
Other Investments [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	$ 26	$ 0

Investment Income, Excluding Capital Gains or Losses

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Amount before accretion (amortization) of purchase discount (premium) of interest income and dividend income on nonoperating securities.

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Amount of expenses related to the generation of investment income.

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Amount after accretion (amortization) of discount (premium), and investment expense, of interest income and dividend income on nonoperating securities.

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The amount of other than temporary impairment (OTTI) losses on equity securities, OTTI related to credit losses on debt securities, and OTTI losses on debt securities when the entity intends to sell the securities or it is more likely than not that the entity will be required to sell the securities before recovery of its amortized cost basis. Additionally, this item includes OTTI losses recognized during the period on investments accounted for under the cost method of accounting.

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The net realized gains or losses on investments during the period, not including gains or losses on securities separately or otherwise categorized as trading, available-for-sale, or held-to-maturity.

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