Investments and Cash - Net Investment Income (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Net Investment Income
Gross investment income	$ 82	$ 100
Investment expenses	(2)	(2)
Net investment income	80	98
Securities, Managed Externally [Member]
Net Investment Income
Gross investment income	62	72
Investments, Managed Internally [Member]
Net Investment Income
Gross investment income	$ 20	$ 28

Represents the total of interest and dividend income, including any amortization and accretion (as applicable) of discounts and premiums, earned from (1) loans and leases whether held-for-sale or held-in-portfolio; (2) investment securities; (3) federal funds sold; (4) securities purchased under agreements to resell; (5) investments in banker's acceptances, commercial paper, or certificates of deposit; (6) dividend income; or (7) other investments not otherwise specified herein.

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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 220
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Amount of expenses related to the generation of investment income.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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-SubTopic 10
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Amount, after investment expense, of income earned from investments in securities and real estate. Includes, but is not limited to, real estate investment, policy loans, dividends, and interest. Excludes realized gain (loss) on investments.

+ References

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-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
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-Paragraph 1
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