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, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income tax at federal statutory rate	$ (10,883)	$ (9,811)	$ (6,659)
Increase (decrease) in tax resulting from:
State income tax expense, net of federal tax effect	(3,657)	(2,749)	(421)
Nondeductible permanent items	3,522	(1,522)	1,506
Foreign rate differential	(367)	552	599
Tax rate change		134	7,226
Adjustment to deferred taxes	(1,904)	307	37
Change in valuation allowance	22,481	15,805	(2,291)
Uncertain tax positions	128	143	76
Nonqualified stock option and performance award windfall upon exercise	(9,128)	(1,983)
Other	233	(80)	(26)
Total	$ 425	$ 796	$ 47