Significant Balance Sheet Components - Property and Equipment (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Property Plant And Equipment [Line Items]
Total property and equipment	$ 23,387	$ 22,683
Accumulated depreciation and amortization	(19,496)	(17,879)
Total property and equipment-net	3,891	4,804
Computers and appliances
Property Plant And Equipment [Line Items]
Total property and equipment	13,589	13,300
Purchased software
Property Plant And Equipment [Line Items]
Total property and equipment	4,235	4,235
Furniture and fixtures
Property Plant And Equipment [Line Items]
Total property and equipment	1,745	1,745
Leasehold improvements
Property Plant And Equipment [Line Items]
Total property and equipment	$ 3,818	$ 3,403