Commitments and Contingencies	3 Months Ended
Commitments and Contingencies	Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	10. Commitments and Contingencies Operating Leases The Company leases its office, laboratory and manufacturing space under non-cancelable operating leases. Total rent expense under these operating leases was $1.6 million and $1.5 million for the three months ended March 31, 2015 and 2014, respectively. Other Commitments In March 2015, the Company received an award of $1.4 million of tax incentives from the Massachusetts Life Sciences Center, which allows the Company to monetize approximately $1.2 million of state research and development tax credits. In exchange for these incentives, the Company pledged to hire an incremental 75 employees and to maintain the additional headcount through at least December 31, 2019. The Company has deferred and will amortize the benefit of the monetization on a straight-line basis over the five-year performance period, commencing with a cumulative catch-up when the pledge is achieved. Failure to achieve this commitment could result in the Company being required to repay some or all of these incentives.

The entire disclosure for commitments and contingencies.