Balance Sheet Components - Components of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Balance Sheet Components [Abstract]
Accrued salary and payroll-related expenses	$ 2,972	$ 3,695
Deferred strategic agreement revenues	2,721	934
Accrued liabilities	1,983	1,249
Income taxes payable	636	883
Finance lease liabilities	777	866
Advanced billings	437	859
Customer advances	282	432
Sales and use tax payable	4	244
Deferred rent	0	538
Other	909	932
Total accrued expenses and other current liabilities	$ 10,721	$ 10,632	[1]

[1] Derived from the Company’s audited consolidated financial statements as of December 31, 2018.