Fair Value Measurements - Schedule of Fair Value Measurements by Level for Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Cash equivalents	$ 34,859	$ 35,834
Warrant liabilities		(527)
Fair Value, Inputs, Level 1 [Member] | Recurring [Member]
Cash equivalents	34,859	35,834
Warrant liabilities
Fair Value, Inputs, Level 2 [Member] | Recurring [Member]
Cash equivalents
Warrant liabilities
Fair Value, Inputs, Level 3 [Member] | Recurring [Member]
Cash equivalents
Warrant liabilities		$ (527)