Fair Value of Financial Assets and Liabilities - Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Liability:
Derivative liability	$ 12,124
Recurring Basis
Assets:
Total assets at fair value		$ 50,906
Liability:
Derivative liability	12,124
Fair Value, Net Asset (Liability), Total	57,280
Money Market Funds | Recurring Basis
Assets:
Cash equivalents	45,156	50,906
Level 2 | Recurring Basis
Assets:
Total assets at fair value		50,906
Liability:
Fair Value, Net Asset (Liability), Total	45,156
Level 2 | Money Market Funds | Recurring Basis
Assets:
Cash equivalents	45,156	$ 50,906
Level 3 | Recurring Basis
Liability:
Derivative liability	12,124
Fair Value, Net Asset (Liability), Total	$ 12,124