Condensed Consolidated Statements of Comprehensive Loss (Unaudited) (USD $) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Statement [Abstract]
Net loss	$ (12,677)	$ (22,792)	$ (25,717)	$ (48,365)
Other comprehensive income/(loss):
Unrealized gain on available-for-sale securities	7	160	11	312
Reclassification of realized gains included in net loss	(10)	(134)	(83)	(269)
Comprehensive loss	$ (12,680)	$ (22,766)	$ (25,789)	$ (48,322)