Commitments and Contingencies - Details Textual (Details) ft² in Thousands, $ in Thousands	1 Months Ended	12 Months Ended
	May. 31, 2015 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Jan. 20, 2016 USD ($) ft²
Operating Leased Assets [Line Items]
Operating Leases, Rent Expense, Net		$ 2,089	$ 1,944	$ 1,610
Lease payment due in 2016		1,487
2017		1,454
2018		1,488
Lease payment due thereafter		0
21 Erie Street Cambridge Massachusetts | Subsequent Event
Operating Leased Assets [Line Items]
Lease payment reduction by 2016					$ 502
Lease payment reduction in 2017					1,223
Lease payment reduction in 2018					1,252
Lease payment reduction in 2019					1,280
Lease payment reduction in 2020					$ 461
ARE_MA Region No. 20, LLC | Subsequent Event
Operating Leased Assets [Line Items]
Area of real estate property | ft²					30
Lease payment due in 2016					$ 216
2017					725
2018					785
Lease payment due thereafter					7,346
Security deposit					307
Receivable, leasehold Improvements					889
Operating Leases, Landlord Reimbursement for Lease Improvements, Additional Potential Payment					$ 444
Service Agreements
Operating Leased Assets [Line Items]
Quarterly Fermentation Service Fees	$ 600
Prepaid Expense	$ 1,000
Quarterly Contractual Fixed Fee Payment		$ 520