Balance Sheet Components (Details) - Intangible assets - USD ($) $ in Thousands	Dec. 31, 2018	Feb. 13, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	$ 22,180	$ 24,080	$ 80
Less accumulated amortization	2,767	40	40
Intangible assets, net	19,413	24,040	40
Purchased Technology [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	22,100	22,400
In Process Research and Development [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross		1,600
Intellectual Property [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	$ 80	$ 80	$ 80