Convertible Notes, Other Debts And Capital Leases - Additional Information (Detail) $ / shares in Units, shares in Millions			3 Months Ended	12 Months Ended
		Dec. 14, 2015 shares	Jun. 30, 2017 USD ($) $ / shares	Dec. 31, 2015 USD ($) day $ / shares	Dec. 31, 2016 USD ($)
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage				4.00%
Debt Instrument, Face Amount			$ 128,250,000	$ 128,250,000	$ 128,250,000
Debt Instrument, Convertible, Conversion Ratio				173.9978
Debt Conversion, Converted Instrument, Amount				$ 1,000
Debt Instrument, Convertible, Conversion Price | $ / shares			$ 5.75	$ 5.75
Debt Issuance Cost, Gross, Noncurrent				$ 4,100,000
Percentage Of Principal Amount Of Convertible Notes Is Equal To Repurchase Price				100.00%
Debt Instrument Convertible Allocated Amount of Equity Component			$ 26,925,000	$ 26,925,000	26,925,000
Debt Instrument, Unamortized Discount (Premium), Net				4,100,000
Unamortized Debt Issuance Expense			2,401,000	3,223,000	2,689,000
Debt Instrument Convertible Equity Component Issuance Cost			863,000	$ 863,000	863,000
Financing from French government agencies related to various government incentive programs (1)	[1]		13,597,000		17,930,000
Term loans (2)	[2]		1,369,000		1,400,000
Stock price greater or equal 130 percent of Note Conversion Price [Member]
Debt Instrument [Line Items]
Debt Instrument, Convertible, Threshold Trading Days | day				20
Debt Instrument, Convertible, Threshold Consecutive Trading Days				30 days
Debt Instrument, Convertible, Threshold Percentage of Stock Price Trigger				130.00%
Note price less than 98 percent of stock price times conversion rate [Member]
Debt Instrument [Line Items]
Debt Instrument, Convertible, Threshold Trading Days | day				5
Debt Instrument, Convertible, Threshold Consecutive Trading Days				5 days
Debt Instrument, Convertible, Threshold Percentage of Stock Price Trigger				98.00%
Privately Negotiated Transactions [Member]
Debt Instrument [Line Items]
Proceeds from Convertible Debt				$ 49,900,000
Stock Repurchased and Retired During Period, Shares | shares		11.1
TVN [Member]
Debt Instrument [Line Items]
Proceeds from Convertible Debt				$ 74,200,000
Income Taxes Receivable			$ 24,300,000
Loans Backed By French Research And Development Tax Credit Receivables [Member] | TVN [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage			0.60%
Financing from French government agencies related to various government incentive programs (1)	[1]		$ 10,800,000
Adjusted EURIBOR Rate, Term			1 month
Debt Instrument, Basis Spread on Variable Rate			1.30%
Loans From French Government For R&D Innovation Projects [Member]
Debt Instrument [Line Items]
Financing from French government agencies related to various government incentive programs (1)	[1]		$ 2,800,000
Foreign Line of Credit [Member] | BPI France [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Fair Value of Amount Outstanding			0
Other Current Liabilities [Member] | TVN [Member]
Debt Instrument [Line Items]
Term loans (2)			$ 400,000		$ 400,000

[1] As of June 30, 2017, the Company’s TVN French Subsidiary had an aggregate of $13.6 million of loans due to various financing programs of French government agencies, $10.8 million of which are related to loans backed by R&D tax credit receivables. As of June 30, 2017, the TVN French Subsidiary had an aggregate of $24.3 million of R&D tax credit receivables from the French government from 2018 through 2021. (See Note 8, “Balance Sheet Components-Prepaid expenses and other current assets,” for more information). These tax loans have a fixed rate of 0.6%, plus EURIBOR 1 month + 1.3% and mature between 2018 through 2019. The remaining loans of $2.8 million at June 30, 2017 primarily relate to financial support from French government agencies for R&D innovation projects at minimal interest rates and these loans mature between 2020 through 2023.

[2] One of the term loans with a certain financial institution contains annual covenants that require the TVN French Subsidiary to maintain a minimum working capital balance and various other financial covenants and restrictions that limit the French Subsidiary’s ability to incur additional indebtedness. The annual covenant is based on French statutory year-end results and the TVN French Subsidiary failed the 2016 covenant test primarily due to the Company’s plan to integrate TVN’s operations into other subsidiaries for tax planning and logistics purposes. In early 2017, the Company informed the financial institution of the 2016 covenant test results and was told by the financial institution to continue with the original payment schedule. The Company reported the entire loan balance with this financial institution under “Other debts and capital lease obligations, current” in the Condensed Consolidated Balance Sheets. The loan balance was approximately $0.4 million at both June 30, 2017 and December 31, 2016.