Balance Sheet Components - Acquired Intangible Assets, Net (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 250	$ 250
Accumulated Amortization	188	94
Net Book Value	62	156
Developed technology
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	250	250
Accumulated Amortization	188	94
Net Book Value	$ 62	$ 156