Business acquisitions - Narrative (Detail) - USD ($) $ / shares in Units, $ in Billions	May 31, 2026	Jan. 02, 2026
OxyChem [Member]
Business Combination [Line Items]
Business acquisition, cash consideration		$ 9.4
Business acquisition, effective date of acquisition		Jan. 02, 2026
Assets acquired		$ 10.7
Property and equipment acquired		7.0
Liabilities assumed		$ 1.3
Acquisition agreement date		Oct. 01, 2025
Taylor Morrison Home Corporation [Member]
Business Combination [Line Items]
Business acquisition, cash consideration	$ 6.8
Business acquisition, effective date of acquisition	Jul. 24, 2026
Business acquisition, price per share	$ 72.5
Acquisition agreement date	May 31, 2026
Business acquisition, Shareholder approval date	Jul. 22, 2026

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