Fair Value Measurement - Level 3 Liability (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Accounts payable and accrued expenses
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Short-term portion of deferred payments	$ 1,600
Deferred payments
Schedule of changes in fair value of level 3 liability
Balance as of the beginning of period	3,257	$ 4,120
Amounts paid	(1,628)	(1,579)
Other adjustments to fair value	29	716
Balance at end of period	$ 1,658	$ 3,257