Nature of Business - Business Separation (Details)	May 04, 2018 company
Overview
Number of independent publicly traded companies resulting from authorized separation	2

Business Separation, Independent Publicly Traded Companies the Entity Resulting from Authorized Separation of Entity, Number

No definition available.

Name:	irwd_BusinessSeparationIndependentPubliclyTradedCompaniesEntityResultingFromAuthorizedSeparationOfEntityNumber
Namespace Prefix:	irwd_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant