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Commitments - Additional Information (Details) - USD ($) $ in Thousands | 3 Months Ended |
--- | --- | ---
Mar. 31, 2019 | Dec. 31, 2018
Recorded Unconditional Purchase Obligation [Line Items] |  |
Restricted cash | $ 40 |
Contractual obligation, due in next twelve months |  | $ 8,653
Contractual obligation |  | 14,743
Pre-clinical Research Study Obligations [Member] |  |
Recorded Unconditional Purchase Obligation [Line Items] |  |
Contractual obligation, due in next twelve months | 1,800 | 1,800
Contractual obligation | $ 2,500 | $ 3,000
Minimum [Member] |  |
Recorded Unconditional Purchase Obligation [Line Items] |  |
Operating and financing lease, lease term | 2 years |
Maximum [Member] |  |
Recorded Unconditional Purchase Obligation [Line Items] |  |
Operating and financing lease, lease term | 11 years |

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