Certain Balance Sheet Components - Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
French R&D tax credits receivable (1)	[1]	$ 7,305	$ 6,609
Contract assets (2)	[2]	3,834
Deferred cost of revenue		3,671	4,440
Prepaid maintenance, royalty, rent, property taxes and VAT		3,497	3,867
Capitalized commission		1,098
Restricted cash		0	530	$ 732
Other		3,875	3,485
Prepaid Expense and Other Assets, Total		$ 23,280	$ 18,931

[1] The Company’s TVN subsidiary in France (the “TVN French Subsidiary”) participates in the French Crédit d’Impôt Recherche (“CIR”) program (the “R&D tax credits”) which allows companies to monetize eligible research expenses. The R&D tax credits can be used to offset against income tax payable to the French government in each of the four years after being incurred, or if not utilized, are recoverable in cash. The amount of R&D tax credits recoverable are subject to audit by the French government and during the year ended December 31, 2018 and 2017, the French government approved the 2014 and 2013 claims and refunded $6.4 million to the TVN French Subsidiary in each of the periods, respectively. The remaining R&D tax credits receivable at December 31, 2018 were approximately $26.5 million and are expected to be recoverable from 2019 through 2022 with $7.3 million reported as a component of “Prepaid and other Current Assets” and $19.2 million reported as a component of “Other Long-term Assets” on the Company’s Consolidated Balance Sheets.

[2] Contract assets reflect the satisfied performance obligations for which the Company does not yet have an unconditional right to consideration.