Restricted Cash	12 Months Ended
Dec. 31, 2017
Receivables [Abstract]
Restricted Cash	7. Restricted Cash The Company is required to maintain stand-by letters of credit as a security deposit under each of the Shelton Lease and the Stamford Lease (refer to Note 16, Commitments and Contingencies). The fair value of each letter of credit approximates its contract value. In each case, the Company’s bank requires the Company to maintain restricted cash balances to serve as collateral for the letter of credit issued to the respective landlords by the bank. During December 2017, the letter of credit for the Shelton Lease expired and the related restricted cash balance was reclassified to cash and cash equivalents on the Company’s Balance Sheet. As of December 31, 2017, the restricted cash balance for the Stamford lease was invested in a commercial money market account. The letter of credit balance for the Stamford Lease remains at $769 through May 2019 and may, upon request from the Company, thereafter be reduced to $408 through the end of the lease term in November 2023. The reduction in the balance of the Letter of Credit for the Stamford Lease is contingent upon the Company not being in default of any provisions of that lease prior to request for the reduction. As of December 31, 2016, the Company had $700 of restricted cash related to the Shelton lease in current assets. As of December 31, 2017 and 2016, the Company had $769 of restricted cash related to the Stamford lease in long-term assets.

7. Restricted Cash

The Company is required to maintain stand-by letters of credit as a security deposit under each of the Shelton Lease and the Stamford Lease (refer to Note 16, Commitments and Contingencies). The fair value of each letter of credit approximates its contract value. In each case, the Company’s bank requires the Company to maintain restricted cash balances to serve as collateral for the letter of credit issued to the respective landlords by the bank. During December 2017, the letter of credit for the Shelton Lease expired and the related restricted cash balance was reclassified to cash and cash equivalents on the Company’s Balance Sheet. As of December 31, 2017, the restricted cash balance for the Stamford lease was invested in a commercial money market account.

The letter of credit balance for the Stamford Lease remains at $769 through May 2019 and may, upon request from the Company, thereafter be reduced to $408 through the end of the lease term in November 2023. The reduction in the balance of the Letter of Credit for the Stamford Lease is contingent upon the Company not being in default of any provisions of that lease prior to request for the reduction. As of December 31, 2016, the Company had $700 of restricted cash related to the Shelton lease in current assets. As of December 31, 2017 and 2016, the Company had $769 of restricted cash related to the Stamford lease in long-term assets.