Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Accumulated Deficit [Member]	Total
Net loss for the period from May 19, 2014 (inception) through December 31, 2014				$ (2,811)	$ (2,811)
Balance at Dec. 31, 2014	$ 8	16,343		(277)	16,074
Balance, shares at Dec. 31, 2014	7,565
Stock-based compensation expense		402			402
Net loss				(2,811)	(2,811)
Balance at Dec. 31, 2015	$ 8	16,745		(3,088)	$ 13,665
Balance, shares at Dec. 31, 2015	7,565				7,565
Net loss for the period from May 19, 2014 (inception) through December 31, 2014				(9,518)	$ (9,518)
Issuance of common stock upon initial public offering, net of issuance costs	$ 5	20,283			20,288
Issuance of common stock upon initial public offering, net of issuance costs, shares	5,750
Stock-based compensation expense		870			870
Unrealized gain (loss) on available-for-sale securities, net of tax			(7)		(7)
Net loss				(9,518)	(9,518)
Balance at Dec. 31, 2016	$ 13	$ 37,898	$ (7)	$ (12,606)	$ 25,298
Balance, shares at Dec. 31, 2016	13,315				13,315