Investment gains (losses) - Narrative (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Jan. 31, 2023
Derivative Instruments, Gain (Loss) [Line Items]
Sales of equity securities	$ 143,359.0	$ 40,631.0	$ 33,664.0
Taxable gains (losses) on sales of equity securities	$ 101,100.0	$ 5,000.0	$ 769.0
Pilot Travel Centers LLC [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Equity interest ownership percentage		38.60%		38.60%
Other Investment gains from remeasurement		$ 3,000.0

Taxable gains (loss) on sales of equity securities.

No definition available.

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- Definition

Percentage of equity in the acquiree held by the acquirer immediately before the acquisition date in a business combination.

+ References

No definition available.

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- Definition

In a business combination achieved in stages, this element represents the amount of net gain (loss) recognized by the entity as a result of remeasuring to fair value the equity interest in the acquiree it held before the business combination.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (g)(2)
-Publisher FASB
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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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4E
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480434/815-10-50-4E

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- Definition

Amount of cash inflow from sale of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI), classified as investing activity.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 19
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-19

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-Name Accounting Standards Codification
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-Topic 321
-Publisher FASB
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