Name:	knsa_ContractualObligationClinicalAndRegulatoryMilestoneFuturePayments
Namespace Prefix:	knsa_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The amount of additional specified annual net sales threshold, for the calculation of the milestone payment.

No definition available.

Name:	knsa_ContractualObligationMilestonePaymentAdditionalSalesThreshold
Namespace Prefix:	knsa_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The amount of annual net sales to be excluded from the calculation of the milestone payment.

No definition available.

Name:	knsa_ContractualObligationMilestonePaymentSalesExcluded
Namespace Prefix:	knsa_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Amount of future maximum contractual obligation for milestone payment upon the achievement of annual net sales thresholds.

No definition available.

Name:	knsa_ContractualObligationSalesMilestoneFutureMaximumPayments
Namespace Prefix:	knsa_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount of future maximum contractual obligation for additional milestone payment upon the achievement of annual net sales thresholds.

No definition available.

Name:	knsa_ContractualObligationSalesMilestoneMaximumFutureAdditionalPayments
Namespace Prefix:	knsa_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The amount of milestone payment to be paid by the company upon the achievement of specified clinical and regulatory milestones.

No definition available.

Name:	knsa_ContractualObligationUponSpecifiedClinicalAndRegulatoryMilestoneAchievement
Namespace Prefix:	knsa_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The amount of milestone payment commitment remaining to be paid by the company upon the achievement of specified clinical and regulatory milestones.

No definition available.

Name:	knsa_ContractualObligationUponSpecifiedClinicalAndRegulatoryMilestoneAchievementCommitmentRemaining
Namespace Prefix:	knsa_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The maximum percentage of royalty payable on annual net sales of licensed products on a escalating tiers basis.

No definition available.

Name:	knsa_MaximumPercentageOfRoyaltyPayableOnAnnualNetSalesOfLicensedProducts
Namespace Prefix:	knsa_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

The notice period upon which the Company can terminate the agreement in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

No definition available.

Name:	knsa_TimePeriodToTerminateAgreement
Namespace Prefix:	knsa_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

The period which both parties can terminate the agreement on uncured material breaches, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

No definition available.

Name:	knsa_TimePeriodToTerminateAgreementByBothPartiesUnderUncuredMaterialBreaches
Namespace Prefix:	knsa_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 808
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-Name Accounting Standards Codification
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-Paragraph 1
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-Publisher FASB
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Data Type:	xbrli:stringItemType
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Period Type:	duration

Amount of expense for research and development. Includes, but is not limited to, cost for computer software product to be sold, leased, or otherwise marketed and writeoff of research and development assets acquired in transaction other than business combination or joint venture formation or both. Excludes write-down of intangible asset acquired in business combination or from joint venture formation or both, used in research and development activity.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 985
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481283/985-20-50-2

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 730
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
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-Publisher FASB
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Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 912
-SubTopic 730
-Name Accounting Standards Codification
-Section 25
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479532/912-730-25-1