Balance Sheet Components - Accounts Receivable, Net, Prepaid Expenses and Other Current Assets, Inventories, Property and Equipment, Net (Detail) - USD ($) $ in Thousands		Jun. 30, 2017	Dec. 31, 2016
Accounts receivable, net:
Accounts receivable		$ 66,892	$ 91,596
Less: allowances for doubtful accounts, returns and discounts		(6,465)	(4,831)
Total		60,427	86,765
Prepaid expenses and other current assets:
Deferred cost of revenue		5,615	6,856
French R&D tax credits receivable(1)	[1]	6,277	5,895
Prepaid maintenance, royalty, rent, property taxes and value added tax		6,574	5,526
Prepaid customer incentive(2)	[2]	746	1,162
Restricted cash(3)	[3]	802	731
Other		4,304	6,149
Prepaid Expense and Other Assets, Current		24,318	26,319
Inventories:
Raw materials		9,179	9,889
Work-in-process		1,789	2,318
Finished goods		11,643	17,776
Service-related spares		12,519	11,210
Total inventories, net		35,130	41,193
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross		140,666	155,956
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment		(109,042)	(123,792)
Property, Plant and Equipment, Net		31,624	32,164
Accrued Liabilities, Current [Abstract]
Accrued employee compensation and related expenses		17,671	19,377
Accrued TVN VDP, current (1)		3,915	6,597
Accrued warranty		4,142	4,862
Customer deposits		3,848	4,537
Contingent inventory reserves		3,671	2,210
Accrued royalty payments		2,797	1,912
Others		14,228	15,655
Accrued Liabilities, Current		50,272	55,150
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross		86,841	97,989
Capitalized software [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross		32,639	34,519
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross		14,406	14,455
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross		$ 6,780	$ 8,993

[1] The Company’s acquired 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. The R&D tax credit receivables at June 30, 2017 were approximately $24.3 million and are expected to be recoverable from 2018 through 2021 with $6.3 million reported under “Prepaid and other Current Assets” and $18.0 million reported under “Other Long-term Assets” on the Company’s Condensed Consolidated Balance Sheets.

[2] On September 26, 2016, the Company issued a warrant to purchase shares of its common stock (the “Warrant”) to Comcast pursuant to which Comcast may, subject to certain vesting provisions, purchase up to 7,816,162 shares of the Company’s common stock subject to adjustment in accordance with the terms of the Warrant, for a per share exercise price of $4.76. The portion of the Warrant which vested on September 26, 2016 had a value of approximately $1.6 million and is deemed a customer incentive paid upfront and cumulatively, $0.9 million of this prepaid incentive has been recorded as a reduction to the Company’s net revenues from Comcast. The remaining $0.7 million of this prepaid incentive is reported as an asset under “Prepaid expenses and other current assets” on the Company’s Condensed Consolidated Balance Sheet as of June 30, 2017. The Company considers this asset to be recoverable based on the expectation of Comcast’s future purchases of the pertinent products.

[3] The restricted cash balances are held as cash collateral security for certain bank guarantees. These restricted funds are invested in bank deposits and cannot be withdrawn from the Company’s accounts without the prior written consent of the applicable secured party. Additionally, as of June 30, 2017, the Company recorded approximately $1.1 million of restricted cash for the bank guarantee associated with the TVN French Subsidiary’s office building lease. This amount is reported under “Other Long-term Assets” on the Company’s Condensed Consolidated Balance Sheets. June 30, 2017December 31, 2016Inventories: Raw materials$9,179 $9,889Work-in-process1,789 2,318Finished goods11,643 17,776Service-related spares12,519 11,210Total$35,130 $41,193