Investment gains (losses) - Narrative (Detail) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2024	Mar. 31, 2023	Jan. 31, 2023
Derivative Instruments, Gain (Loss) [Line Items]
Sales of equity securities	$ 19,972	$ 13,283
Taxable gains (losses) on sales of equity securities	$ 14,200	2,200
Pilot Travel Centers LLC [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Non-cash gain from remeasurement		$ 3,000
Equity interest ownership percentage		38.60%	38.60%

Business combination step acquisition equity interest in acquiree remeasurement non-cash gain or (loss).

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- Definition

Taxable gains (loss) on sales of equity securities.

+ References

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.

+ Details

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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

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-SubTopic 10
-Topic 321
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479567/321-10-45-1

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