Income Taxes - Provision and Components of Net Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Taxes
Income tax benefit	$ 691	$ 799
Domestic and foreign components of net loss
Domestic	(72,271)	(37,511)	$ (34,556)
Foreign	(5,607)	(2,212)	(2,401)
Loss before income tax benefit	$ (77,878)	$ (39,723)	$ (36,957)