Condensed Consolidated Statements of Stockholders' Equity (Deficit) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
2019 Public Offering
Stock offering transaction cost	$ 1,683
January 2019 Public Offering
Stock offering transaction cost			$ 739
May 2019 Public Offering
Stock offering transaction cost			$ 1,683
2018 Public Offering
Stock offering transaction cost		$ 2,096		$ 2,096
Over-Allotment Option
Overallotment related to transaction cost				$ 10