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Debt - Description of fair value adjustments for guaranteed notes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024	Dec. 31, 2024
Debt Instrument [Line Items]
Gains (Losses)	$ (20)	$ (2)	$ (45)	$ 21
Cumulative Fair Value Hedging Adjustments Included in Carrying Amount of Debt	89		89		$ 134
Guaranteed Notes due 2025, 1.25%
Debt Instrument [Line Items]
Gains (Losses)	(1)	(1)	(3)	(1)
Cumulative Fair Value Hedging Adjustments Included in Carrying Amount of Debt	$ 1		$ 1		4
Guaranteed Notes due 2025, 1.25% \| Issued by LYB International Finance III LLC:
Debt Instrument [Line Items]
Stated interest rate (in percent)	1.25%		1.25%
Guaranteed Notes due 2026, 0.875%
Debt Instrument [Line Items]
Gains (Losses)	$ (1)	0	$ (1)	0
Cumulative Fair Value Hedging Adjustments Included in Carrying Amount of Debt	$ 3		$ 3		4
Guaranteed Notes due 2026, 0.875% \| Issued by LYB International Finance II B.V.:
Debt Instrument [Line Items]
Stated interest rate (in percent)	0.875%		0.875%
Guaranteed Notes due 2027, 3.5%
Debt Instrument [Line Items]
Gains (Losses)	$ (1)	0	$ (3)	4
Cumulative Fair Value Hedging Adjustments Included in Carrying Amount of Debt	$ 2		$ 2		5
Guaranteed Notes due 2027, 3.5% \| Issued by LYB International Finance II B.V.:
Debt Instrument [Line Items]
Stated interest rate (in percent)	3.50%		3.50%
Guaranteed Notes due 2030, 3.375%
Debt Instrument [Line Items]
Gains (Losses)	$ (2)	0	$ (5)	3
Cumulative Fair Value Hedging Adjustments Included in Carrying Amount of Debt	$ 13		$ 13		18
Guaranteed Notes due 2030, 3.375% \| Issued by LYB International Finance III LLC:
Debt Instrument [Line Items]
Stated interest rate (in percent)	3.375%		3.375%
Guaranteed Notes due 2030, 2.25%
Debt Instrument [Line Items]
Gains (Losses)	$ (2)	0	$ (5)	3
Cumulative Fair Value Hedging Adjustments Included in Carrying Amount of Debt	$ 16		$ 16		21
Guaranteed Notes due 2030, 2.25% \| Issued by LYB International Finance III LLC:
Debt Instrument [Line Items]
Stated interest rate (in percent)	2.25%		2.25%
Guaranteed Notes due 2031, 1.625%
Debt Instrument [Line Items]
Gains (Losses)	$ (1)	1	$ 1	2
Cumulative Fair Value Hedging Adjustments Included in Carrying Amount of Debt	$ 2		$ 2		1
Guaranteed Notes due 2031, 1.625% \| Issued by LYB International Finance II B.V.:
Debt Instrument [Line Items]
Stated interest rate (in percent)	1.625%		1.625%
Guaranteed Notes due 2050, 4.2%
Debt Instrument [Line Items]
Gains (Losses)	$ (1)	(1)	$ (2)	(3)
Cumulative Fair Value Hedging Adjustments Included in Carrying Amount of Debt	$ 0		$ 0		2
Guaranteed Notes due 2050, 4.2% \| Issued by LYB International Finance III LLC:
Debt Instrument [Line Items]
Stated interest rate (in percent)	4.20%		4.20%
Guaranteed Notes due 2051, 3.625%
Debt Instrument [Line Items]
Gains (Losses)	$ (9)	(1)	$ (23)	10
Cumulative Fair Value Hedging Adjustments Included in Carrying Amount of Debt	$ 47		$ 47		70
Guaranteed Notes due 2051, 3.625% \| Issued by LYB International Finance III LLC:
Debt Instrument [Line Items]
Stated interest rate (in percent)	3.625%		3.625%
Guaranteed Notes due 2060, 3.8%
Debt Instrument [Line Items]
Gains (Losses)	$ (2)	$ 0	$ (4)	$ 3
Cumulative Fair Value Hedging Adjustments Included in Carrying Amount of Debt	$ 5		$ 5		$ 9
Guaranteed Notes due 2060, 3.8% \| Issued by LYB International Finance III LLC:
Debt Instrument [Line Items]
Stated interest rate (in percent)	3.80%		3.80%