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Equity method investments - Narrative (Detail) - USD ($)	6 Months Ended
	Jun. 30, 2025	Sep. 30, 2025
The Kraft Heinz Company [Member]
Schedule Of Equity Method Investments [Line Items]
Equity method investment ownership percentage		27.50%
Equity method investments, pre-tax impairment loss	$ 5,000,000,000
Excess of equity method carrying value	5,000,000,000	$ 2,400,000,000
Equity in net earnings of impairment loss after tax	8,600,000,000
Occidental Petroleum Corporation [Member]
Schedule Of Equity Method Investments [Line Items]
Equity method investment ownership percentage		26.90%
Occidental Petroleum Corporation [Member] | Common Stock [Member]
Schedule Of Equity Method Investments [Line Items]
Percentage of excess of carrying values over fair values of investments		24.00%
Excess of carrying value over fair value of equity investment		$ 3,950,000,000
Excess of carrying value of investment over investees equity	$ 9,100,000,000
Berkadia Commercial Mortgage LLC [Member]
Schedule Of Equity Method Investments [Line Items]
Equity method investment ownership percentage		50.00%
Berkadia Commercial Mortgage LLC [Member] | Jefferies Financial Group Inc. [Member]
Schedule Of Equity Method Investments [Line Items]
Equity method investment ownership percentage		50.00%
Berkadia Commercial Mortgage LLC [Member] | Commercial Paper [Member]
Schedule Of Equity Method Investments [Line Items]
Maximum outstanding balance of commercial paper borrowings		$ 1,500,000,000

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Amount of after-tax impairment loss resulting from write-down of assets lacking physical substance and having a projected indefinite period of benefit to fair value and from write-down of assets representing future economic benefit arising from other assets acquired in business combination.

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Difference between amount at which an investment accounted for under the equity method of accounting is carried (reported) on the balance sheet and amount of underlying equity in net assets the reporting Entity has in the investee.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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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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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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