Represents the percentage of profits and losses shared under the collaboration agreement.

No definition available.

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

- Definition

Adjustment to the amount of discount used to measure fair value for lack of ability to convert business interests into cash quickly..

+ References

No definition available.

+ Details

Name:	incy_FairValueInputsAmountOfDiscountForLackOfMarketability
Namespace Prefix:	incy_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Represents the additional milestone payments to be made under the license agreement.

+ References

No definition available.

+ Details

Name:	incy_LicenseAgreementAdditionalMilestonePayments
Namespace Prefix:	incy_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the amount of the upfront payment made under the license agreement.

+ References

No definition available.

+ Details

Name:	incy_LicenseAgreementUpfrontPaymentAmountPaid
Namespace Prefix:	incy_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the per share price of common stock under Stock Purchase Agreement.

+ References

No definition available.

+ Details

Name:	incy_PerSharePriceOfCommonStockUnderStockPurchaseAgreement
Namespace Prefix:	incy_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the percentage of associated future global development costs from the initiation of a Phase IIb trial provided the entity elects to co-develop any compounds and/or indications.

+ References

No definition available.

+ Details

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

- Definition

Represents the percentage of net sales attributable to additional royalties.

+ References

No definition available.

+ Details

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

- Definition

Represents the percentage of profits (losses).

+ References

No definition available.

+ Details

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

- Definition

Represents the percentage of reverse royalties on sale of future products.

+ References

No definition available.

+ Details

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

- Definition

Represents range of tiered, double-digit royalty payments on future global sales if product is successfully commercialized.

+ References

No definition available.

+ Details

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

- Definition

Represents the purchase of common stock under Stock Purchase Agreement.

+ References

No definition available.

+ Details

Name:	incy_PurchaseOfCommonStockUnderStockPurchaseAgreementInShares
Namespace Prefix:	incy_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the amount of the total consideration paid under purchase agreement during the period.

+ References

No definition available.

+ Details

Name:	incy_TotalConsiderationPaidUnderPurchaseAgreement
Namespace Prefix:	incy_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of expenses incurred but not yet paid nor invoiced, and liabilities classified as other.

+ References

No definition available.

+ Details

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

- Definition

Sum of the carrying amounts as of the balance sheet date of all assets that are expected to be realized in cash, sold, or consumed within one year (or the normal operating cycle, if longer). Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=118951113&loc=d3e6801-107765

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.9)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=118951113&loc=d3e6676-107765

+ Details

Name:	us-gaap_AssetsCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value of the entity's equity.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

+ Details

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

- Definition

This element represents the aggregate cost of investments accounted for under the equity method of accounting.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.12)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_EquityMethodInvestmentAggregateCost
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

+ Details

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The amount of net income (loss) reported by an equity method investment of the entity.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(g))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 28
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=75031198&loc=d3e14064-108612

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=109222650&loc=SL51721683-107760

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33912-111571

+ Details

Name:	us-gaap_EquityMethodInvestmentSummarizedFinancialInformationNetIncomeLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of revenue from sale of product and rendering of service reported by equity method investee.

+ References

+ Details

Name:	us-gaap_EquityMethodInvestmentSummarizedFinancialInformationRevenue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of unrealized gain (loss) on investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 321
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=116654751&loc=SL75117546-209714

+ Details

Name:	us-gaap_EquitySecuritiesFvNiUnrealizedGainLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

+ References

+ Details

Name:	us-gaap_InvestmentsFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Total obligations incurred as part of normal operations that are expected to be paid during the following twelve months or within one business cycle, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.21)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

The total amount of investments that are intended to be held for an extended period of time (longer than one operating cycle).

+ References

+ Details

Name:	us-gaap_LongTermInvestments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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_RelatedPartyTransactionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 985
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6501960&loc=d3e128462-111756

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 730
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6420194&loc=d3e21568-108373

+ Details

Name:	us-gaap_ResearchAndDevelopmentExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Price of a single share of a number of saleable stocks of a company.

+ References

No definition available.

+ Details

Name:	us-gaap_SharePrice
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_BalanceSheetLocationAxis=us-gaap_AccruedLiabilitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=country_US
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=us-gaap_NonUsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	incy_AchievementOfMilestoneAxis=incy_DevelopmentAndRegulatoryMilestonesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	incy_AchievementOfMilestoneAxis=incy_CommercializationMilestonesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=incy_MerusNVMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

License agreements - Merus (Details) $ / shares in Units, $ in Thousands, € in Millions, shares in Millions		1 Months Ended				3 Months Ended			6 Months Ended		12 Months Ended
	Jan. 23, 2017 USD ($) $ / shares	Dec. 31, 2017	Feb. 28, 2017 USD ($)	Jan. 31, 2017 USD ($)	Dec. 31, 2016 USD ($) $ / shares shares	Jun. 30, 2020 USD ($)	Mar. 31, 2020 EUR (€)	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2019 USD ($)
License agreements
Long term investments						$ 248,731			$ 248,731			$ 133,657
Research and development expense						286,601		$ 289,363	1,371,888	$ 559,908
Unrealized gain (loss) on long term investments						72,274		(4,625)	24,142	16,364
Current assets						2,077,625			2,077,625			2,481,488
Current liabilities						556,513			556,513			513,340
Minimum
License agreements
Royalty payments on future global net sales (as a percent)		15.00%
Merus
License agreements
Associated future global development costs , if elected to co-develop (as a percent)				35.00%
Upfront payment under license agreement			$ 120,000
Research and development expense						1,900		1,700	4,200	4,300
Merus \| Accrued and other liabilities
License agreements
Accrued and other liabilities						2,000			2,000			1,600
Merus \| U.S.
License agreements
Profit sharing (as a percent)				50.00%
Percentage of profit (losses)				50.00%
Merus \| Minimum
License agreements
Royalty payments on future global net sales (as a percent)				6.00%
Merus \| Minimum \| U.S.
License agreements
Royalty payments on future global net sales (as a percent)				6.00%
Merus \| Minimum \| Non-U.S.
License agreements
Royalty payments on future global net sales (as a percent)				6.00%
Merus \| Maximum
License agreements
Royalty payments on future global net sales (as a percent)				10.00%
Percentage of reverse royalty				4.00%
Merus \| Maximum \| U.S.
License agreements
Royalty payments on future global net sales (as a percent)				10.00%
Percentage of additional royalties				4.00%
Merus \| Maximum \| Non-U.S.
License agreements
Royalty payments on future global net sales (as a percent)				10.00%
Merus \| Maximum \| Development and Regulatory Milestones
License agreements
Additional milestone payments under the license agreement				$ 100,000
Merus \| Maximum \| Sales and Commercial Milestones
License agreements
Additional milestone payments under the license agreement				$ 250,000
Merus
License agreements
Per share price of common stock \| $ / shares	$ 24.50
Discount for lack of marketability	$ 5,600
Fair value of shares on the issuance date	72,800
Total consideration paid	80,000
Long term investments	$ 72,800
Research and development expense											$ 7,200
Fair market value of our long term investments						$ 51,500			$ 51,500			$ 45,100
Ownership percentage (as a percent)						11.00%			11.00%
Unrealized gain (loss) on long term investments						$ 12,700		$ (400)	$ 6,400	$ 2,100
Total revenues \| €							€ 6.3
Net loss \| €							€ (16.5)
Merus \| Stock purchase agreement
License agreements
Purchase of common stock under Stock Purchase Agreement (in shares ) \| shares					3.2
Purchase price of common stock					$ 80,000
Per share price \| $ / shares					$ 25.00