Summary of significant accounting policies - Revenue Recognition (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2019	Dec. 31, 2018
Revenue recognition
Accrued sales allowances	$ 69.4	$ 44.8
Percentage of Medicare Part D insurance coverage gap mandate to be funded by manufacturers	50.00%
ICLUSIG
Revenue recognition
Amortization period	12 years 6 months

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

No definition available.

+ Details

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

- Definition

Amount of accumulated credit loss for right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=82913815&loc=SL49130533-203044

+ Details

Name:	us-gaap_ContractWithCustomerAssetAccumulatedAllowanceForCreditLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

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