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Stock-Based Compensation - Summary of Employee and Non-Employee Restricted Stock Activity (Details) - Unvested Restricted Common Stock
12 Months Ended
Dec. 31, 2018
$ / shares
shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]  
Shares, Unvested restricted common stock, Beginning balance | shares 33,307
Shares, Vested | shares (26,444)
Shares, Unvested restricted common stock, Ending balance | shares 6,863
Weighted Average Grant Date Fair Value, Unvested restricted common stock, Beginning balance | $ / shares $ 1.84
Weighted Average Grant Date Fair Value, Vested | $ / shares 1.87
Weighted Average Grant Date Fair Value, Unvested restricted common stock, Ending balance | $ / shares $ 1.73