Document and Entity Information	9 Months Ended
	Sep. 30, 2013	Oct. 10, 2013 Class A common stock	Oct. 10, 2013 Class B common stock
Entity Registrant Name	IRONWOOD PHARMACEUTICALS INC
Entity Central Index Key	0001446847
Document Type	10-Q
Document Period End Date	Sep. 30, 2013
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		97,477,669	23,425,910
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	Q3