Notes Payable - Schedule of Debt (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Debt Instrument
Total notes payable	$ 41,066	$ 40,773
Less: current portion of notes payable	(1,316)	(1,269)
Notes payable, net of current portion	39,750	39,504
Medium-term Notes | Term Loan Agreement
Debt Instrument
Total notes payable	37,624	37,031
Deferred issuance costs	2,900	3,000
Line of Credit | Equipment Lease Credit Facility
Debt Instrument
Total notes payable	3,442	3,742
Deferred issuance costs	$ 40	$ 45