Equity Securities - (Summary of Investments in Marketable Equity Securities) (Detail) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Equity securities, Cost	$ 416	$ 435
Equity securities, Unrealized gains (losses)	157	222
Equity securities, Estimated fair value	573	657
Preferred Stock
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Equity securities, Cost	17	17
Equity securities, Unrealized gains (losses)	(1)	0
Equity securities, Estimated fair value	16	17
Common Stock
Schedule Of Trading Securities And Other Trading Assets [Line Items]
Equity securities, Cost	399	418
Equity securities, Unrealized gains (losses)	158	222
Equity securities, Estimated fair value	$ 557	$ 640

Amount of unrealized gain (loss) on investment in marketable equity securities.

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- Definition

Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI), classified as current.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=123594786&loc=SL75136599-209740

+ Details

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- Definition

Cost of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). Excludes equity method investment and investment in equity security without readily determinable fair value.

+ References

No definition available.

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- Definition

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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