Summary of significant accounting policies - Revenue Recognition (Details)	3 Months Ended
Mar. 31, 2020
Revenue recognition
Percentage of Medicare Part D insurance coverage gap mandate to be funded by manufacturers	70.00%
Increase in required patient spending in the Medicare Part D insurance coverage gap (as a percent)	30.00%
MorphoSys AG
Revenue recognition
Profit (loss) sharing ratio	50.00%
ICLUSIG
Revenue recognition
Amortization period	12 years 6 months

Ratio of sharing profit and losses under the collaboration agreement.

No definition available.

Name:	incy_CollaborationAgreementProfitLossSharingRatio
Namespace Prefix:	incy_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the Medicare Part D insurance coverage gap percent increase for required patient spending.

+ References

No definition available.

+ Details

Name:	incy_MedicarePartDInsuranceCoverageGapIncreaseInEligiblePatientSpendingPercentage
Namespace Prefix:	incy_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the percentage of Medicare Part D insurance coverage gap mandate to be funded by manufacturers for prescription drugs sold to eligible patients.

+ References

No definition available.

+ Details

Name:	incy_PercentageOfMedicarePartDInsuranceCoverageGapRequiredToBeFundedByManufacturers
Namespace Prefix:	incy_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

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.

+ References

No definition available.

+ Details

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

- Definition

Remaining amortization period of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetsRemainingAmortizationPeriod1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_TypeOfArrangementAxis=incy_MorphosysAgMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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