Balance Sheet Components - Schedule of Allowance for Sales Incentives (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance	$ (21,897)
Ending balance	(14,259)	$ (21,897)
Allowance for Sales Incentives
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance	(13,750)	(10,442)
Charged to revenue	(16,663)	(50,958)
Utilization of sales return/incentive reserve	21,830	47,650
Ending balance	$ (8,583)	$ (13,750)