Summary of significant accounting policies (Details)	6 Months Ended
Jun. 30, 2020 issuer instrument item
Concentrations of Credit Risk
Number of issuer to which company limits the amount of credit exposure other than US Government guaranteed securities \| issuer	1
Number of financial investment to which company limits the amount of credit exposure other than US Government guaranteed securities \| instrument	1
Variable Interest Entities
Number of entities in which variable interest held \| item	0
JAKAFI
Inventory
Shelf life for finished goods inventory, maximum	36 months
ICLUSIG
Inventory
Shelf life for finished goods inventory, maximum	36 months
PEMAZYRE
Inventory
Period of lower average per unit cost of materials	48 months
Shelf life for finished goods inventory, maximum	36 months

No definition available.

Name:	incy_ConcentrationOfCreditRiskAbstract
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Data Type:	xbrli:stringItemType
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Represents the number of financial investment to which entity limits the amount of credit exposure other than US Government guaranteed securities.

No definition available.

Name:	incy_CreditExposureLimitationNumberOfFinancialInvestmentOtherThanUnitedStatesGovernmentGuaranteedSecurities
Namespace Prefix:	incy_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Represents the number of issuer to which entity limits the amount of credit exposure other than US Government guaranteed securities.

No definition available.

Name:	incy_CreditExposureLimitationNumberOfIssuerOtherThanUnitedStatesGovernmentGuaranteedSecurities
Namespace Prefix:	incy_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

Represents the maximum useful life of merchandise or goods held by the entity that are readily available for sale.

No definition available.

Name:	incy_InventoryFinishedGoodsUsefulLifeMaximum
Namespace Prefix:	incy_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Represents the length of time in which cost of goods sold will deviate from average due to unusual and/or infrequent conditions.

No definition available.

Name:	incy_PeriodOfDeviationFromAverageCostOfGoodsSold
Namespace Prefix:	incy_
Data Type:	xbrli:durationItemType
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Period Type:	duration

n/a

No definition available.

Name:	incy_VariableInterestEntitiesAbstract
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Represents the number of Variable Interest Entities as on date.

No definition available.

Name:	incy_VariableInterestEntitiesNumber
Namespace Prefix:	incy_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

No definition available.

Name:	us-gaap_InventoryNetAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Name:	srt_ProductOrServiceAxis=incy_JAKAFIMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_ProductOrServiceAxis=incy_ICLUSIGMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_ProductOrServiceAxis=incy_PemazyreMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: