Condensed Consolidated Statements Of Operations And Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Condensed Consolidated Statements Of Operations And Comprehensive Loss [Abstract]
Revenue
Operating expenses:
General and administrative	4,159	893	9,151	2,063
Research and development	3,200	1,739	7,333	4,182
Amortization of intangible assets	166	166	499	499
Total operating expenses	7,525	2,798	16,983	6,744
Other income:
Interest income	39	31	119	35
Total other income	39	31	119	35
Net loss	(7,486)	(2,767)	(16,864)	(6,709)
Other comprehensive loss:
Unrealized gain on available-for-sale securities, net of tax	4		5
Comprehensive loss	$ (7,482)	$ (2,767)	$ (16,859)	$ (6,709)
Net loss per share:
Basic and diluted net loss per share	$ (0.52)	$ (0.21)	$ (1.19)	$ (0.66)
Weighted average shares used to compute net loss per common share - basic and diluted	14,381	13,315	14,141	10,235