Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Revenue
Total revenue	$ 1,371	$ 40,000
Operating expenses
Research and development	11,075	94,612
Write-off of acquired in-process research and development	38,313
General and administrative	27,395	29,870
Total operating expenses	76,783	124,482
Loss from operations	(75,412)	(84,482)
Interest income	989	847
Interest expense	(2,429)	(528)
Other income (expense), net	519	(1,063)
Net loss before provision for income taxes	(76,333)	(85,226)
Benefit from income taxes		(247)
Net loss	$ (76,333)	$ (84,979)
Net loss per share- basic and diluted	$ (10.64)	$ (14.47)
Weighted-average common shares used to compute net loss per share- basic and diluted	7,171	5,871
Contract Revenue [Member]
Revenue
Total revenue		$ 40,000
Grant Revenue [Member]
Revenue
Total revenue	$ 1,371