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Net Loss Per Share (Details) - shares
Mar. 31, 2018
Dec. 31, 2017
Mar. 31, 2017
Earnings Per Share [Abstract]      
Number of shares issued or committed for issuance under outstanding stock options 871,757   838,582
Restricted stock and shares reserved for restricted stock units      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Number of shares of restricted stock and shares reserved for restricted stock units outstanding 182,053 201,702 203,622