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Alternative investments as a percentage of overall invested assets.

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Amortized cost of portfolio rated below investment grade.

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No definition available.

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This item represents the change in gross unrealized holding gain or loss on available-for-sale securities that has been included in accumulated other comprehensive income, a separate component of shareholders' equity, during the period.

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No definition available.

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Percentage of the fair value of portfolio that was rated investment grade as of balance sheet date.

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No definition available.

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Fair value of portfolio rated below investment grade.

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Financing receivable, Number of loans past due

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Impaired financing receivable, number of impaired loans

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This item represents total investment commitments as of the balance sheet date for fixed maturity available-for-sale securities, limited partnerships, real estate and mortgage loans on real estate.

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This item represents investment commitments as of the balance sheet date for limited partnerships.

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This item represents investment commitments as of the balance sheet date for private placements.

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This item represents investment commitments as of the balance sheet date for mortgage loans.

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Number of partnerships represented in alternative investment portfolio.

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This item represents the loss severity as a percentage of first lien loans that was considered as one of the potential factors in reaching a conclusion that the available-for-sale investments are other than temporarily impaired and the amount of such impairment determined to be related to credit loss recognized in earnings.

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No definition available.

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This item represents the loss severity as a percentage of defaulted second lien loans that was considered as one of the potential factors in reaching a conclusion that the available-for-sale investments are other than temporarily impaired and the amount of such impairment determined to be related to credit loss recognized in earnings.

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No definition available.

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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.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Fair value of collateral permitted, by contact or custom, to be sold or re-pledged.

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Fair value of the collateral, or portion thereof, that has been re-pledged, delivered, or otherwise used.

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Amount of allowance for credit losses related to recorded investment.

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Unpaid principal balance of impaired financing receivables for which there is a related allowance for credit losses.

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Amount of unrealized holding gain (loss) recognized in the income statement for investments in debt and equity securities and other forms of securities that provide ownership interests classified as trading.

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Investments (Narrative) (Details) $ in Millions	12 Months Ended
Investments (Narrative) (Details) $ in Millions	Dec. 31, 2019 USD ($) security item	Dec. 31, 2018 USD ($) security item	Dec. 31, 2017 USD ($)
Investment [Line Items]
Increase (decrease) in gross AFS securities unrealized losses	$ 2,200
Unrealized gain (loss), trading securities	$ 228	$ (58)	$ 7
Number of partnerships in alternative investment portfolio \| item	258	237
Alternative investments as a percentage of overall invested assets	1.00%	1.00%
Fair value of collateral received that we are permitted to sell or re-pledge	$ 25
Securities that have been re-pledged	25
Investment commitments	2,000
Investment commitments for limited partnerships	1,000
Investment commitments for mortgage loans on real estate	553
Investment commitments for private placements	425
Federal Home Loan Mortgage Corporation [Member] \| Investments [Member]
Investment [Line Items]
Fair value	$ 1,300	$ 1,400
Concentration risk, percentage	1.00%	1.00%
Federal National Mortgage Association [Member] \| Investments [Member]
Investment [Line Items]
Fair value	$ 1,000	$ 1,300
Concentration risk, percentage	1.00%	1.00%
Consumer Non-Cyclical Industry [Member] \| Investments [Member]
Investment [Line Items]
Fair value	$ 16,300	$ 14,500
Concentration risk, percentage	12.00%	13.00%
Financial Service [Member] \| Investments [Member]
Investment [Line Items]
Fair value	$ 16,400	$ 14,200
Concentration risk, percentage	12.00%	12.00%
Corporate Bonds [Member]
Investment [Line Items]
Percentage of fair value rated as investment grade	96.00%	96.00%
Amortized cost of portfolio rated below investment grade	$ 3,200
Fair value of portfolio rated below investment grade	$ 3,300	$ 3,000
MBS [Member]
Investment [Line Items]
Severity of second lien loans	100.00%
Severity of first lien loans	30.00%
Commercial [Member]
Investment [Line Items]
Number of impaired loans \| security	1	0
Commercial [Member] \| Maximum [Member]
Investment [Line Items]
Impaired financing receivable, principal balance	$ 1
Commercial [Member] \| Mortgage Loans On Real Estate [Member] \| Geographic Concentration Risk [Member] \| California [Member]
Investment [Line Items]
Concentration risk, percentage	24.00%	23.00%
Commercial [Member] \| Mortgage Loans On Real Estate [Member] \| Geographic Concentration Risk [Member] \| Texas [Member]
Investment [Line Items]
Concentration risk, percentage	11.00%	12.00%
Residential [Member]
Investment [Line Items]
Number of loans past due \| security	38	0
Number of impaired loans \| security	4	0
Impaired financing receivable, principal balance	$ 1
Impaired financing receivable, allowance	$ 2
Residential [Member] \| Maximum [Member]
Investment [Line Items]
Impaired financing receivable, allowance		$ 1
Residential [Member] \| Mortgage Loans On Real Estate [Member] \| Geographic Concentration Risk [Member] \| California [Member]
Investment [Line Items]
Concentration risk, percentage	34.00%	34.00%
Residential [Member] \| Mortgage Loans On Real Estate [Member] \| Geographic Concentration Risk [Member] \| Florida [Member]
Investment [Line Items]
Concentration risk, percentage	20.00%	19.00%