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v3.19.3.a.u2

Segment Information - Narrative (Details) | Dec. 31, 2019 segment
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Operating Segments [Abstract] |
Number of reporting segments | 2

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- Definition Number Of Reportable Segments + References No definition available. + Details
Name: | alc_NumberOfReportableSegments
Namespace Prefix: | alc_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

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- Definition Operating Segments [Abstract] + References No definition available. + Details
Name: | alc_OperatingSegmentsAbstract
Namespace Prefix: | alc_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration