Segment Information (Reconciliation of Total Segment Income from Operations to Consolidated Income before Income Taxes) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Segment Reporting Information [Line Items]
Total reportable segments income (loss) from operations	$ (766)	$ 180	$ (907)	$ 809
Interest expense	(41)	(39)	(120)	(120)
Other income, net	32	44	93	153
Income (loss) before income taxes	(775)	185	(934)	842
Operating Segments
Segment Reporting Information [Line Items]
Total reportable segments income (loss) from operations	(751)	193	(862)	848
Other income, net	12	12	25	54
Corporate and other
Segment Reporting Information [Line Items]
Total reportable segments income (loss) from operations	(15)	(13)	(45)	(39)
Other income, net	$ 20	$ 32	$ 68	$ 99

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

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+ Details

- Definition

The net result for the period of deducting operating expenses from operating revenues.

+ References

+ Details

WESTLAKE CORP 10-Q