Assets and liabilities at fair value - Schedule of Debt Measured at Fair Value (Details) - Level 2 - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Unsecured senior notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Amount	$ 3,829	$ 3,828
Fair Value	3,781	3,833
Private placement notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying Amount	300	300
Fair Value	$ 299	$ 300

Amount, after deduction of unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation.

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+ Details

- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

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+ Details