Investments (Schedule Of Components Of Restricted Assets) (Detail) - Asset Pledged as Collateral without Right - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Investments [Line Items]
Trust funds	$ 9,137	$ 8,482
Assets pledged under repurchase agreements	3,273	2,924
Deposits with U.S. regulatory authorities	2,565	2,544
Deposits with non-U.S. regulatory authorities and other	4,714	4,464
Total restricted assets	$ 19,689	$ 18,414

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

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- Definition

Restricted assets that are deposits with non-US regulatory authorities and Other Pledged Assets

+ References

No definition available.

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- Definition

Restricted assets that are deposits with US regulatory authorities.

+ References

No definition available.

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- Definition

The total amount of cash and securities held by third party trustees pursuant to terms of debt instruments or other agreements as of the date of each statement of financial position presented, which can be used by the trustee only to pay the noncurrent portion of specified obligations.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(b))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-1

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- Definition

Cash and investments whose use in whole or in part is restricted for the long-term, generally by contractual agreements or regulatory requirements. For use in an unclassified balance sheet.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 954
-SubTopic 210
-Name Accounting Standards Codification
-Section 45
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477220/954-210-45-4

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 954
-SubTopic 210
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478600/954-210-50-2

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- Definition

Fair value of securities pledged as collateral against securities sold under agreement to repurchase.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 12
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483444/210-20-55-12

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