Balance Sheet Components - Other Assets (Details) - USD ($) $ in Thousands		1 Months Ended	12 Months Ended
	Aug. 08, 2017	Aug. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Aug. 14, 2017	Apr. 30, 2016
Balance Sheet Components [Line Items]
Agreement term			4 years
Total consideration						$ 3,200
Deferred costs included in other long-term assets			$ 1,000	$ 1,800
Amortization of deferred costs			$ 800	$ 800
Common stock, shares issued			62,082,348	54,040,000
Payments of debt issuance costs				$ 287
Amortization of debt discount			$ 391	154
Noncurrent assets			3,317	$ 3,979
2017 Term Loan
Balance Sheet Components [Line Items]
Common stock, shares issued		300,000			300,000
Payments of debt issuance costs	$ 300
Amortization of debt discount			100
Debt discount		$ 2,700	600
Debt, increase (decrease)		(2,000)
Debt instrument, fee amount		2,400
Noncurrent assets		700
Remaining borrowing capacity	$ 25,000	$ 50,000	50,000
Evercord
Balance Sheet Components [Line Items]
Noncurrent accounts receivable			$ 500