Investment Holding Level 4 Concentration of Credit Risk (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Concentration Risk [Line Items]
Fair Value, Concentration of Risk, Investments	$ 0	$ 0
Concentration Risk, Benchmark Description	greater than 10% of the Company's stockholder's equity	greater than 10% of the Company's stockholder's equity
Mortgage Loans on Real Estate, Carrying Amount of Mortgages	$ 2,241	$ 2,100
Secured Debt, Repurchase Agreements	$ 0
Corporate Debt Securities [Member] \| Walt Disney Corporation [Member]
Concentration Risk [Line Items]
Largest Exposure by Issuer, Percent of Invested Assets	1.00%
Corporate Debt Securities [Member] \| IBM Corporation [Member]
Concentration Risk [Line Items]
Largest Exposure by Issuer, Percent of Invested Assets	1.00%
Corporate Debt Securities [Member] \| CVS Health Corp [Member]
Concentration Risk [Line Items]
Largest Exposure by Issuer, Percent of Invested Assets		1.00%
Corporate Debt Securities [Member] \| Microsoft Corporation [Member]
Concentration Risk [Line Items]
Largest Exposure by Issuer, Percent of Invested Assets	1.00%	1.00%
Corporate Debt Securities [Member] \| HSBC Holding plc. [Member]
Concentration Risk [Line Items]
Largest Exposure by Issuer, Percent of Invested Assets		1.00%
Financial Services [Member] \| Corporate Debt Securities [Member]
Concentration Risk [Line Items]
Largest Exposure by Sector, Percent of Invested Assets	7.00%	7.00%
Public Utility [Member] \| Corporate Debt Securities [Member]
Concentration Risk [Line Items]
Largest Exposure by Sector, Percent of Invested Assets	7.00%	8.00%
CMBS [Member] \| Corporate Debt Securities [Member]
Concentration Risk [Line Items]
Largest Exposure by Sector, Percent of Invested Assets	7.00%	7.00%

The percent of invested assets by the Company's largest exposure by issuer.

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The percent of invested assets by the Company's largest exposure by sector.

+ References

No definition available.

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Identifies or describes the benchmark that serves as the denominator in the calculation of the percentage of concentration risk.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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This item represents disclosure of all significant concentrations of credit risk or market risk arising from the subject financial instrument (as defined), whether from an individual counterparty or groups of counterparties.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
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Amount of investment in mortgage loan on real estate by entity with substantial portion of business acquiring and holding investment real estate or interest in real estate.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 948
-SubTopic 310
-Section S99
-Paragraph 1
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Carrying value, as of the balance sheet date, of securities sold under agreements to repurchase where the transferor maintains effective control over the assets, accounting for them as secured debt.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 10
-Section 55
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