Fair Value of Financial Assets and Liabilities - Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Liability:
Derivative liability	$ 32,535	$ 12,124
Recurring Basis
Liability:
Derivative liability	32,535	12,124
Total	114,896	57,280
Money Market Funds | Recurring Basis
Assets:
Cash equivalents	82,361	45,156
Level 2 | Recurring Basis
Liability:
Total	82,361	45,156
Level 2 | Money Market Funds | Recurring Basis
Assets:
Cash equivalents	82,361	45,156
Level 3 | Recurring Basis
Liability:
Derivative liability	32,535	12,124
Total	$ 32,535	$ 12,124