Deferred tax assets and liabilities - Impact on current taxes payable (Details) - USD ($) $ in Billions	Dec. 31, 2024	Dec. 31, 2023
Income Taxes [Abstract]
Deferred tax assets	$ 1.2	$ 1.2
Deferred tax liabilities	$ 1.7	$ 1.8

Deferred Tax Liabilities, Impact On Current Tax Liabilities, After Twelve Months

No definition available.

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Namespace Prefix:	alc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant