Investments in equity securities - Narrative (Detail) - Occidental Corporation [Member] - Investment Commitment [Member] $ / shares in Units, $ in Billions	3 Months Ended
Mar. 31, 2022 USD ($) $ / shares shares
Summary of Investment Holdings [Line Items]
Number of common shares that can be purchased \| shares	83,860,000
Exercise price for warrants, per share \| $ / shares	$ 59.62
Cumulative Perpetual Preferred Stock [Member]
Summary of Investment Holdings [Line Items]
Investment in preferred stock, liquidation value \| $	$ 10
Investment in preferred stock, stated dividend rate	8.00%
Investment in preferred stock, redemption year start	2029
Investment in preferred stock, redemption price percentage of liquidation preference	105.00%

Liquidation value of preferred shares.

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- Definition

Percentage price of liquidation value at which a preferred stock investment can be redeemed by the issuer.

+ References

No definition available.

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- Definition

Preferred stock investment redemption year start.

+ References

No definition available.

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- Definition

Exercise price per share or per unit of warrants or rights outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=123467817&loc=d3e21475-112644

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- Definition

Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares.

+ References

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- Definition

The percentage rate used to calculate dividend payments on preferred stock.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123467817&loc=SL123496158-112644

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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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