Balance Sheet Components - Intangible Assets, net (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Intangible Assets, net
Less: Accumulated amortization	$ (53,000)		$ (53,000)		$ (49,000)
Intangible assets, net	28,000		28,000		32,000
Amortization expense	2,000	$ 1,000	4,000	$ 4,000
License Agreement
Intangible Assets, net
Intangible assets, gross	$ 81,000		$ 81,000		$ 81,000