Summary of Significant Accounting Policies - Schedule of Fair Value Measurements by Level for Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Cash equivalents	$ 19,731,000	$ 35,834,000
Warrant liabilities		(527,000)
Fair Value, Inputs, Level 1 [Member] | Recurring [Member]
Cash equivalents	19,731,000	35,834,000
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		$ (527,000)