Condensed Consolidated Statements of Operations (USD $) In Thousands, except Share data	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Collaborative arrangements revenue	$ 11,262	$ 9,188	$ 21,499	$ 18,026
Operating expenses:
Research and development	19,409	19,897	38,964	37,446
General and administrative	10,805	6,601	20,029	12,386
Total operating expenses	30,214	26,498	58,993	49,832
Loss from operations	(18,952)	(17,310)	(37,494)	(31,806)
Other income (expense):
Interest expense	(17)	(44)	(33)	(97)
Interest and investment income	125	189	279	257
Other income			3
Other income (expense), net	108	145	249	160
Net loss from continuing operations	(18,844)	(17,165)	(37,245)	(31,646)
Net loss from discontinued operations		(44)		(1,816)
Net loss	(18,844)	(17,209)	(37,245)	(33,462)
Net loss from discontinued operations attributable to noncontrolling interest		73		402
Net loss attributable to Ironwood Pharmaceuticals, Inc.	$ (18,844)	$ (17,136)	$ (37,245)	$ (33,060)
Net loss per share attributable to Ironwood Pharmaceuticals, Inc.-basic:
Continuing operations - basic (in dollars per share)	$ (0.19)	$ (0.18)	$ (0.37)	$ (0.39)
Discontinued operations - basic (in dollars per share)				$ (0.02)
Net loss per share - basic (in dollars per share)	$ (0.19)	$ (0.18)	$ (0.37)	$ (0.41)
Net loss per share attributable to Ironwood Pharmaceuticals, Inc.-diluted:
Continuing operations - diluted (in dollars per share)	$ (0.19)	$ (0.18)	$ (0.37)	$ (0.39)
Discontinued operations - diluted (in dollars per share)				$ (0.02)
Net loss per share - diluted (in dollars per share)	$ (0.19)	$ (0.18)	$ (0.37)	$ (0.41)
Weighted average number of common shares used in net loss per share attributable to Ironwood Pharmaceuticals, Inc.-basic (in shares)	99,674,969	97,642,330	99,458,336	80,893,200
Weighted average number of common shares used in net loss per share attributable to Ironwood Pharmaceuticals, Inc.-diluted (in shares)	99,674,969	97,642,330	99,458,336	80,893,200