Investments (Narrative) (Detail) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2020	Dec. 31, 2019
Investments [Line Items]
Equity Method Investment, Ownership Percentage	100.00%	100.00%
Restricted assets in fixed maturities and short-term investments	$ 19,600	$ 19,600	$ 21,000
Restricted assets in cash	152	152	$ 109
Debt Securities, Available-for-sale, Allowance for Credit Loss, Purchased with Credit Deterioration, Increase	$ 3	5
Debt Securities, Available-for-sale, Purchased with Credit Deterioration, Allowance for Credit Loss at Acquisition Date		5
Debt Securities, Available-for-sale, Purchased with Credit Deterioration, Amount at Par Value		143
Debt Securities, Available-for-sale, Purchased with Credit Deterioration, Amount at Purchase Price		$ 107

[Line Items] for This table lists the investments. The line items identify information about all investments.

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Amount of increase in allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale) and beneficial interest, purchased with credit deterioration.

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Amount of allowance for credit loss at acquisition date of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), purchased with credit deterioration.

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Amount at par value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), purchased with credit deterioration.

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The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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Amount of cash and cash equivalents restricted as to withdrawal or usage. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Investments which are not defined as or included in marketable (debt, equity, or other) securities whose use is restricted in whole or in part, generally by contractual agreements or regulatory requirements. For use in an unclassified balance sheet.

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