Represents the period over which the entity will perform development activities as per the collaborative arrangement.

No definition available.

Name:	irwd_CollaborativeArrangementEstimatedDevelopmentPeriod
Namespace Prefix:	irwd_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the period, before assessment of approval, over which the entity will perform development activities as per the collaborative arrangement.

+ References

No definition available.

+ Details

Name:	irwd_CollaborativeArrangementEstimatedDevelopmentPeriodBeforeAssessment
Namespace Prefix:	irwd_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the revenue recognized from the sale of linaclotide API.

+ References

No definition available.

+ Details

Name:	irwd_CollaborativeArrangementRevenueRecognizedFromSaleOfAPI
Namespace Prefix:	irwd_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the amount to be received by the company upon completion of milestone.

+ References

No definition available.

+ Details

Name:	irwd_MilestonePaymentToBeReceivedByCompanyUponMilestoneAchievement
Namespace Prefix:	irwd_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Represents the total number of milestone payments to be received once all milestones have been achieved.

+ References

No definition available.

+ Details

Name:	irwd_NumberOfMilestonePayments
Namespace Prefix:	irwd_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the revenue recognized as a result of the change in estimate of the development period for up-front license fees.

+ References

No definition available.

+ Details

Name:	irwd_RevenueRecognitionImpactOfChangeInEstimateOfDevelopmentPeriod
Namespace Prefix:	irwd_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents deferred revenue recognized as up-front license fees in the current period.

+ References

No definition available.

+ Details

Name:	irwd_RevenueRecognizedUpFrontLicenseFee
Namespace Prefix:	irwd_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the total payments to be received once all milestones have been achieved.

+ References

No definition available.

+ Details

Name:	irwd_TotalMilestonePaymentsToBeReceived
Namespace Prefix:	irwd_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Represents the amount of deferred revenue remaining to be recognized for up-front license fees received.

+ References

No definition available.

+ Details

Name:	irwd_UpFrontLicenseFeeDeferred
Namespace Prefix:	irwd_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

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

- Definition

Amount of deferred revenue as of balance sheet date. Deferred revenue represents collections of cash or other assets related to a revenue producing activity for which revenue has not yet been recognized. Generally, an entity records deferred revenue when it receives consideration from a customer before achieving certain criteria that must be met for revenue to be recognized in conformity with GAAP.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 13

-Section A

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 605

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SAB TOPIC 13.A.4(a).Q1 Response)

-URI http://asc.fasb.org/extlink&oid=27012821&loc=d3e214044-122780

+ Details

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

- Definition

Cash received from licensees for license fees during the current period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 25

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3536-108585

+ Details

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

- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Article 5

+ Details

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

- Details

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

- Details

Name:	us-gaap_TypeOfArrangementAxis=us-gaap_CollaborativeArrangementMember
Namespace Prefix:
Data Type:	na
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Collaboration and License Agreements (Details 3) (USD $)	3 Months Ended		1 Months Ended		5 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013	Nov. 30, 2009	Mar. 31, 2015
Collaboration and License Agreements
Collaborative arrangements revenue	$ 28,932,000us-gaap_Revenues	$ 14,605,000us-gaap_Revenues
Collaborative arrangement
Collaboration and License Agreements
Collaborative arrangements revenue	2,300,000
Astellas Pharma Inc.
Collaboration and License Agreements
Up-front fee received				30,000,000
Estimated development period prior to assessment			115 months
Estimated development period			85 months
Revenue recognized as a result of revised estimate of development period	500,000	500,000
Up-front license fee revenue recognized	1,300,000	1,300,000
Up-front license fee deferred	10,100,000				10,100,000
Collaborative arrangements revenue	2,276,000	1,269,000
Revenue recognized from sale of API	500,000	1,300,000
Astellas Pharma Inc. \| Additional development milestones
Collaboration and License Agreements
Total number of milestone payments to be received (in payments)	3
Astellas Pharma Inc. \| Additional development milestones \| Maximum
Collaboration and License Agreements
Total milestone payments to be received	45,000,000
Astellas Pharma Inc. \| Phase 3 milestones
Collaboration and License Agreements
Milestone payment to be received by company upon milestone achievement	15,000,000
Revenue recognized over the remaining development period	4,300,000				4,300,000
Collaborative arrangements revenue	500,000				10,700,000
Astellas Pharma Inc. \| Japanese NDA equivalent filing milestone
Collaboration and License Agreements
Total number of milestone payments to be received (in payments)	2
Milestone payment to be received by company upon milestone achievement	15,000,000
Astellas Pharma Inc. \| Approval of Japanese NDA equivalent filing milestone
Collaboration and License Agreements
Milestone payment to be received by company upon milestone achievement	$ 15,000,000