Fair Value of Financial Assets and Liabilities - Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Liability:
Derivative liability	$ 15,528	$ 12,124
Recurring Basis
Liability:
Derivative liability	15,528	12,124
Total	60,849	57,280
Money Market Funds | Recurring Basis
Assets:
Cash equivalents	45,321	45,156
Level 2 | Recurring Basis
Liability:
Total	45,321	45,156
Level 2 | Money Market Funds | Recurring Basis
Assets:
Cash equivalents	45,321	45,156
Level 3 | Recurring Basis
Liability:
Derivative liability	15,528	12,124
Total	$ 15,528	$ 12,124