Income Taxes - Reconciliation of Provision for Income Taxes at Statutory Rate and Provision (Benefit) for Income Taxes at Effective Tax Rate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income tax at federal statutory rate	$ (20,089)	$ (10,883)	$ (9,811)
Increase (decrease) in tax resulting from:
State income tax expense, net of federal tax effect	(3,763)	(3,657)	(2,749)
Nondeductible permanent items	1,659	3,522	(1,522)
Executive Compensation	6,020
Foreign rate differential	(156)	(367)	552
Tax rate change			134
Adjustment to deferred taxes	(3,190)	(1,904)	307
Change in valuation allowance	25,339	22,481	15,805
Uncertain tax positions	151	128	143
Nonqualified stock option and performance award windfall upon exercise	(8,608)	(9,128)	(1,983)
Other	370	233	(80)
Total	$ (2,267)	$ 425	$ 796