Fair Value Disclosure - Schedule of Level 3 Instruments (Details) - Convertible Preferred Stock Warrant Liability $ in Thousands |
12 Months Ended | |||
|---|---|---|---|---|
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Dec. 31, 2017
USD ($)
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| Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] | ||||
| Convertible preferred stock warrant liability — beginning balance | $ 9,990 | |||
| Fair value of new warrants issued | 2,032 | |||
| Change in fair value of preferred stock warrant liability | 40,333 | [1] | ||
| Reclassification to additional paid in capital upon conversion to common warrants | $ (52,355) | |||
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