Post-employment benefits for associates - Schedule of expected future cash flows (Details) $ in Millions	12 Months Ended
Dec. 31, 2023 USD ($)
Pension plans
Employer contributions
2024 (estimated)	$ 11
Other post-employment benefit plans
Employer contributions
2024 (estimated)	0
2024 \| Pension plans
Expected future benefit payments
Settlements	48
2024 \| Other post-employment benefit plans
Expected future benefit payments
Settlements	16
2025 \| Pension plans
Expected future benefit payments
Settlements	33
2025 \| Other post-employment benefit plans
Expected future benefit payments
Settlements	17
2026 \| Pension plans
Expected future benefit payments
Settlements	35
2026 \| Other post-employment benefit plans
Expected future benefit payments
Settlements	18
2027 \| Pension plans
Expected future benefit payments
Settlements	35
2027 \| Other post-employment benefit plans
Expected future benefit payments
Settlements	19
2028 \| Pension plans
Expected future benefit payments
Settlements	35
2028 \| Other post-employment benefit plans
Expected future benefit payments
Settlements	19
2029-2033 \| Pension plans
Expected future benefit payments
Settlements	199
2029-2033 \| Other post-employment benefit plans
Expected future benefit payments
Settlements	$ 91

Defined Benefit Plan, Expected Future Benefit Payment1 [Abstract]

No definition available.

Name:	alc_DefinedBenefitPlanExpectedFutureBenefitPayment1Abstract
Namespace Prefix:	alc_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Defined Benefit Plan, Expected Future Employer Contributions1 [Abstract]

+ References

No definition available.

+ Details

Name:	alc_DefinedBenefitPlanExpectedFutureEmployerContributions1Abstract
Namespace Prefix:	alc_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The estimate of the expected contributions to be made to a defined benefit plan for the next annual reporting period. [Refer: Defined benefit plans [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 19
-IssueDate 2023-01-01
-Paragraph 147
-Subparagraph b
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2023-en-r&anchor=para_147_b&doctype=Standard
-URIDate 2023-03-23

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 19
-IssueDate 2023-01-01
-Paragraph 148
-Subparagraph d
-Clause iii
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2023-en-r&anchor=para_148_d_iii&doctype=Standard
-URIDate 2023-03-23

+ Details

Name:	ifrs-full_EstimateOfContributionsExpectedToBePaidToPlan
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The decrease (increase) in the net defined benefit liability (asset) resulting from payments from the plan in respect of settlements. [Refer: Decrease (increase) in net defined benefit liability (asset) resulting from gains (losses) arising from settlements; Net defined benefit liability (asset); Defined benefit plans [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 19
-IssueDate 2023-01-01
-Paragraph 141
-Subparagraph g
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=19&code=ifrs-tx-2023-en-r&anchor=para_141_g&doctype=Standard
-URIDate 2023-03-23

+ Details

Name:	ifrs-full_PaymentsInRespectOfSettlementsNetDefinedBenefitLiabilityAsset
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	ifrs-full_CharacteristicsOfDefinedBenefitPlansAxis=ifrs-full_PensionDefinedBenefitPlansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_CharacteristicsOfDefinedBenefitPlansAxis=ifrs-full_PostemploymentMedicalDefinedBenefitPlansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_MaturityAxis=ifrs-full_NotLaterThanOneYearMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_MaturityAxis=ifrs-full_LaterThanOneYearAndNotLaterThanTwoYearsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_MaturityAxis=ifrs-full_LaterThanTwoYearsAndNotLaterThanThreeYearsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_MaturityAxis=ifrs-full_LaterThanThreeYearsAndNotLaterThanFourYearsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_MaturityAxis=ifrs-full_LaterThanFourYearsAndNotLaterThanFiveYearsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_MaturityAxis=ifrs-full_LaterThanFiveYearsAndNotLaterThanTenYearsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: