Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net loss	$ (123,914)	$ (126,817)	$ (69,707)
Other comprehensive income:
Unrealized loss on marketable securities	3	0	0
Comprehensive loss	$ (123,911)	$ (126,817)	$ (69,707)