Asset Acquisition and License Agreements	12 Months Ended
Dec. 31, 2014
Research And Development [Abstract]
Asset Acquisition and License Agreements	9. Asset Acquisition and License Agreements Millennium Pharmaceuticals, Inc. (“Millennium”) In November 2003, we acquired patent rights and intellectual property to an ADP Receptor Antagonist Program (“ADP Program”) and a Platelet Biology Program from Millennium. We are obligated to pay royalties on sales of products developed in the ADP Program if product sales are ever achieved. In November 2007, we elected to continue our development of Betrixaban and the Factor Xa backup chemistry beyond December 1, 2007 and accordingly, paid $5.0 million in cash to Millennium, which was charged to research and development expense, as the rights had no alternative future use. We could owe Millennium up to $35.0 million upon the occurrence of specified events related to Betrixaban and royalties on sales of Factor Xa products, if such product sales are ever achieved. Astellas Pharma, Inc. (“Astellas”) In June 2005, we licensed certain rights to research, develop and commercialize Syk inhibitors, including Cerdulatinib, from Astellas. In 2011, under the terms of the license agreement and in connection with the Biogen Idec collaboration agreement to develop Syk, we paid $7.2 million in cash to Astellas, which was charged to research and development expense as the rights had no alternative future use. We may be required to pay Astellas up to $71.5 million upon the achievement of certain regulatory, approval and sales events for each Syk inhibitor we develop. In the event that we enter into an agreement with a third party to develop and commercialize Syk inhibitors, we would be required to pay Astellas 20% of any payments (excluding royalties) received under the collaboration. These payments would be creditable against the aforementioned milestone payments. In addition, we are required to pay Astellas royalties for worldwide sales for any commercial Syk inhibitor product.

9. Asset Acquisition and License Agreements

Millennium Pharmaceuticals, Inc. (“Millennium”)

In November 2003, we acquired patent rights and intellectual property to an ADP Receptor Antagonist Program (“ADP Program”) and a Platelet Biology Program from Millennium. We are obligated to pay royalties on sales of products developed in the ADP Program if product sales are ever achieved.

In November 2007, we elected to continue our development of Betrixaban and the Factor Xa backup chemistry beyond December 1, 2007 and accordingly, paid $5.0 million in cash to Millennium, which was charged to research and development expense, as the rights had no alternative future use. We could owe Millennium up to $35.0 million upon the occurrence of specified events related to Betrixaban and royalties on sales of Factor Xa products, if such product sales are ever achieved.

Astellas Pharma, Inc. (“Astellas”)

In June 2005, we licensed certain rights to research, develop and commercialize Syk inhibitors, including Cerdulatinib, from Astellas.

In 2011, under the terms of the license agreement and in connection with the Biogen Idec collaboration agreement to develop Syk, we paid $7.2 million in cash to Astellas, which was charged to research and development expense as the rights had no alternative future use.

We may be required to pay Astellas up to $71.5 million upon the achievement of certain regulatory, approval and sales events for each Syk inhibitor we develop. In the event that we enter into an agreement with a third party to develop and commercialize Syk inhibitors, we would be required to pay Astellas 20% of any payments (excluding royalties) received under the collaboration. These payments would be creditable against the aforementioned milestone payments. In addition, we are required to pay Astellas royalties for worldwide sales for any commercial Syk inhibitor product.