Balance Sheet Components - Other Assets (Details) - USD ($) $ in Thousands		1 Months Ended	3 Months Ended
	Aug. 08, 2017	Apr. 30, 2016	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Aug. 31, 2017	Aug. 14, 2017
Balance Sheet Components [Line Items]
Agreement term		4 years
Total consideration		$ 3,200
Deferred costs included in other long-term assets			$ 800		$ 1,000
Amortization of deferred costs			$ 200
Common stock, shares issued			63,340,000		62,083,000
Amortization of debt discount			$ 98	$ 98
Debt discount			500
Noncurrent assets			2,802		$ 3,317
2017 Term Loan
Balance Sheet Components [Line Items]
Common stock, shares issued						300,000	300,000
Payments of debt issuance costs	$ 300
Debt discount	2,700					$ 2,700
Debt instrument, fee amount	2,400
Remaining borrowing capacity	25,000					50,000
2017 Term Loan | Direct reduction from outstanding debt balance
Balance Sheet Components [Line Items]
Debt instrument, fee amount	$ 2,000
2017 Term Loan | Noncurrent assets
Balance Sheet Components [Line Items]
Debt instrument, fee amount						$ 700
Evercord | Storage services
Balance Sheet Components [Line Items]
Noncurrent assets			$ 200