Research and License Agreements	3 Months Ended
Mar. 31, 2017
Revenue Recognition [Abstract]
Research and License Agreement	9. Research and License Agreements In October 2011, the Company and Pfizer entered into the Pfizer Agreement that provides Pfizer an exclusive worldwide license to rivipansel for vaso-occlusive crisis associated with sickle cell disease and for other diseases for which the drug candidate may be developed. The Company was responsible for completion of the Phase 2 clinical trial, after which Pfizer assumed all further development and commercialization responsibilities. Upon execution of the Pfizer Agreement, the Company received an up-front payment of $22.5 million. The Pfizer Agreement also provides for potential milestone payments of up to $115.0 million upon the achievement of specified development milestones, including the dosing of the first patients in Phase 3 clinical trials for up to two indications and the first commercial sale of a licensed product in the United States and selected European countries for up to two indications; potential milestone payments of up to $70.0 million upon the achievement of specified regulatory milestones, including the acceptance of our filings for regulatory approval by regulatory authorities in the United States and Europe for up to two indications; and potential milestone payments of up to $135.0 million upon the achievement of specified levels of annual net sales of licensed products. Pfizer has the right to terminate the Pfizer Agreement by giving prior written notice. The Company has determined that each potential future clinical, development and regulatory milestone is substantive. Although sales-based milestones are not considered substantive, they are still recognized upon achievement of the milestone (assuming all other revenue recognition criteria have been met) because there are no undelivered elements that would preclude revenue recognition at that time. The Company is also eligible to receive royalties on future sales contingent upon annual net sales thresholds. In addition, the Company and Pfizer have formed a joint steering committee that will oversee and coordinate activities as set forth in the research program. The $22.5 million up-front payment was recognized over a period of 1.5 years. In May 2014, Pfizer made a $15.0 million non-refundable milestone payment to the Company, which was recognized as revenue by the Company in May 2014 when earned. In June 2015, Pfizer dosed the first patient in the Phase 3 clinical trial of rivipansel, which triggered a non-refundable milestone payment to the Company of $20.0 million, which the Company recognized as revenue in June 2015. The Company did not recognize any revenue under the Pfizer Agreement during the three months ended March 31, 2017 or 2016. In February 2004, the Company entered into a research services agreement (the Research Agreement) with the University of Basel (the University) for biological evaluation of selectin antagonists. Certain patents covering the rivipansel compound are subject to provisions of the Research Agreement. Under the terms of the Research Agreement, the Company will owe to the University 10% of all future milestone and royalty payments received from Pfizer with respect to rivipansel. There were no milestone payments due to the University for the three months ended March 31, 2017 or 2016.

9. Research and License Agreements

In October 2011, the Company and Pfizer entered into the Pfizer Agreement that provides Pfizer an exclusive worldwide license to rivipansel for vaso-occlusive crisis associated with sickle cell disease and for other diseases for which the drug candidate may be developed. The Company was responsible for completion of the Phase 2 clinical trial, after which Pfizer assumed all further development and commercialization responsibilities. Upon execution of the Pfizer Agreement, the Company received an up-front payment of $22.5 million. The Pfizer Agreement also provides for potential milestone payments of up to $115.0 million upon the achievement of specified development milestones, including the dosing of the first patients in Phase 3 clinical trials for up to two indications and the first commercial sale of a licensed product in the United States and selected European countries for up to two indications; potential milestone payments of up to $70.0 million upon the achievement of specified regulatory milestones, including the acceptance of our filings for regulatory approval by regulatory authorities in the United States and Europe for up to two indications; and potential milestone payments of up to $135.0 million upon the achievement of specified levels of annual net sales of licensed products. Pfizer has the right to terminate the Pfizer Agreement by giving prior written notice.

The Company has determined that each potential future clinical, development and regulatory milestone is substantive. Although sales-based milestones are not considered substantive, they are still recognized upon achievement of the milestone (assuming all other revenue recognition criteria have been met) because there are no undelivered elements that would preclude revenue recognition at that time. The Company is also eligible to receive royalties on future sales contingent upon annual net sales thresholds. In addition, the Company and Pfizer have formed a joint steering committee that will oversee and coordinate activities as set forth in the research program. The $22.5 million up-front payment was recognized over a period of 1.5 years. In May 2014, Pfizer made a $15.0 million non-refundable milestone payment to the Company, which was recognized as revenue by the Company in May 2014 when earned. In June 2015, Pfizer dosed the first patient in the Phase 3 clinical trial of rivipansel, which triggered a non-refundable milestone payment to the Company of $20.0 million, which the Company recognized as revenue in June 2015. The Company did not recognize any revenue under the Pfizer Agreement during the three months ended March 31, 2017 or 2016.

In February 2004, the Company entered into a research services agreement (the Research Agreement) with the University of Basel (the University) for biological evaluation of selectin antagonists. Certain patents covering the rivipansel compound are subject to provisions of the Research Agreement. Under the terms of the Research Agreement, the Company will owe to the University 10% of all future milestone and royalty payments received from Pfizer with respect to rivipansel. There were no milestone payments due to the University for the three months ended March 31, 2017 or 2016.