Business Acquisition - Preliminary allocation of the estimated purchase consideration (Details) - USD ($) $ in Thousands			12 Months Ended
		Feb. 29, 2016	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017
Business Combination, Separately Recognized Transactions [Line Items]
Goodwill			$ 237,279	$ 240,618	$ 242,827
TVN [Member]
Business Combination, Separately Recognized Transactions [Line Items]
Cash and cash equivalents			6,843
Accounts receivable, net			14,933
Inventories			3,462
Prepaid expenses and other current assets			2,412
Property and equipment, net			9,942
French R&D tax credit receivables (1)	[1]		26,421
Other long-term assets			2,134
Total assets			66,147
Other debts and capital lease obligations, current			8,362
Accounts payable			12,494
Deferred revenue			2,504
Accrued and other current liabilities			18,365
Other debts and capital lease obligations, long-term			16,087
Other non-current liabilities			6,467
Deferred tax liabilities			2,126
Total liabilities			66,405
Goodwill			41,670
Intangibles			41,100
Total purchase consideration		$ 82,500	$ 82,512

[1] See Note 9, “Certain Balance Sheet Components-Prepaid expenses and other current assets,” for more information on French R&D tax credit receivables.