v3.10.0.1
Fair Value Measurements - Reconciliation of Warrant Liability (Details) - Warrants - USD ($)
$ in Thousands
6 Months Ended
Jun. 30, 2018
Jun. 30, 2017
Reconciliation of warrant liability and embedded derivative    
Balance at beginning of period $ 669 $ 1,226
Exercise of common stock warrants 0 0
Remeasurement of common stock warrants (534) 334
Balance at end of period $ 135 $ 1,560