Investments (Narrative) (Detail) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Investments [Line Items]
Equity Method Investment, Ownership Percentage	100.00%
Restricted assets in fixed maturities and short-term investments	$ 20,900		$ 21,000
Restricted assets in cash	146		$ 109
Mortgage-backed securities
Investments [Line Items]
Credit losses recognized in net income	$ 0	$ 0

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

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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 increase (decrease) in the cumulative amount of credit losses recognized in earnings related to debt securities held for which a portion of an other than temporary impairment (OTTI) was recognized in other comprehensive income (loss).

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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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- Definition

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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