Investments (Concentrations of Credit Risk - Narrative) (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Securities holdings exposure in single issuer greater than stated percentage of Company's equity	10.00%	10.00%
Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged	$ 1,200		$ 1,200
Federal Home Loan Bank, Advances, Branch of FHLB Bank, Amount of Advances	800		800
Investment in Federal Home Loan Bank Stock
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Federal Home Loan Bank, Advances, Branch of FHLB Bank, Amount of Advances	33		33
Foreign government \| Japan
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Fixed maturity securities AFS	31,700		30,200
Foreign government \| Republic of Korea
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Fixed maturity securities AFS	$ 7,200		$ 7,100

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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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

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Amount of advances from the Federal Home Loan Bank (FHLB).

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Amount of the collateral pledged in support of federal home loan bank advances outstanding.

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