Stockholders' Equity - Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ 80,747	$ 20,952
Other comprehensive income, net	10	0
Ending balance	85,114	16,155
Unrealized gains (losses) on short-term investments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(27)
Other comprehensive income (loss) before reclassifications	10
Other comprehensive income, net	10
Ending balance	(17)
AOCI Attributable to Parent
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(27)	0
Other comprehensive income (loss) before reclassifications	10
Other comprehensive income, net	10
Ending balance	$ (17)	$ 0