Nature of the Business (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Accumulated deficit	$ 257,314				$ 257,314		$ 249,655
Net loss	$ 175	$ 7,484	$ 10,007	$ 11,341	$ 7,659	$ 21,348