Long-Term Debt - Change in Fair Value of Initial Warrant (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Change in fair value	$ (2,233)	$ 0	$ 0
Initial Warrant
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	0
Issuance of initial warrant (July 16, 2019)	4,304
Change in fair value	2,233
Ending balance	$ 6,537	$ 0