Organization and Description of the Business (Details) - USD ($)	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Organization and Description of the Business
Number of operating segments							1
Accumulated deficit	$ 430,643,000						$ 430,643,000		$ 413,145,000
Net loss	$ 5,551,000	$ 6,222,000	$ 5,725,000	$ 8,566,000	$ 4,691,000	$ 5,169,000	$ 17,498,000	$ 18,426,000