Condensed Consolidated Statements Of Operations And Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Condensed Consolidated Statements Of Operations And Comprehensive Loss [Abstract]
Revenue
Operating expenses:
General and administrative	4,401	5,383
Research and development	5,842	3,175
Amortization of intangible assets	167	166
Total operating expenses	10,410	8,724
Other income (expense):
Interest income	332	56
Total other income (expense)	332	56
Net loss	(10,078)	(8,668)
Other comprehensive loss:
Unrealized gain on available-for-sale securities	3	48
Comprehensive loss	$ (10,075)	$ (8,620)
Net loss per share:
Basic and diluted net loss per share	$ (0.49)	$ (0.51)
Weighted average shares used to compute net loss per common share - basic and diluted	20,679	16,842