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Convertible Notes and Credit Facilities - Additional Information (Detail) | 3 Months Ended | 12 Months Ended |  |
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Sep. 27, 2019 USD ($) day $ / shares | Dec. 31, 2019 USD ($) day $ / shares | Dec. 31, 2018 USD ($) $ / shares | Dec. 31, 2017 USD ($) | Dec. 31, 2015 USD ($) day $ / shares | Sep. 10, 2019 USD ($) | Sep. 29, 2017 USD ($)
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Common Stock, Par Value Per Share | $ / shares |  |  | $ 0.001 | $ 0.001 |  |  |  |
Loss on debt extinguishment |  |  | $ 5,695,000 | $ 0 | $ 0 |  |  |
Payments of Debt Issuance Costs |  |  | 4,277,000 |  |  |  |  |
Proceeds from convertible debt |  |  | 115,500,000 | 0 | $ 0 |  |  |
Reclassification from APIC to Convertible Debt in Mezzanine Equity |  |  | 2,410,000 |  |  |  |  |
Loans Payable to Bank | [1] |  | 16,566,000 | 18,783,000 |  |  |  |
Income Taxes Receivable |  |  | $ 23,200,000 |  |  |  |  |
Revolving Credit Facility [Member] | JPMORGAN CHASE BANK N.A. [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  | 1.25% |  |  |  |  |
Line of Credit Facility, Current Borrowing Capacity |  |  | $ 0 |  |  |  |  |
Letters of Credit Outstanding, Amount |  |  | 300,000 |  |  |  |  |
Revolving Credit Facility [Member] | Silicon Valley Bank [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Line of Credit Facility, Current Borrowing Capacity |  |  |  |  |  |  | $ 0 | $ 15,000,000
Letters of Credit Outstanding, Amount |  |  |  |  |  |  | $ 2,200,000 |
Outstanding Borrowing Limit Based on Eligible Receivables, Percentage |  |  |  |  |  |  |  | 85.00%
Revolving Credit Facility [Member] | Maximum [Member] | JPMORGAN CHASE BANK N.A. [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Line of Credit Facility, Current Borrowing Capacity |  |  | $ 25,000,000 |  |  |  |  |
London Interbank Offered Rate (LIBOR) [Member] | Revolving Credit Facility [Member] | JPMORGAN CHASE BANK N.A. [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Basis Spread on Variable Rate |  |  | 2.50% |  |  |  |  |
One Month LIBOR [Member] | Revolving Credit Facility [Member] | JPMORGAN CHASE BANK N.A. [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Maturity interest period, Variable Rate |  |  | 1 month |  |  |  |  |
Two Month LIBOR [Member] | Revolving Credit Facility [Member] | JPMORGAN CHASE BANK N.A. [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Maturity interest period, Variable Rate |  |  | 2 months |  |  |  |  |
Three Month LIBOR [Member] | Revolving Credit Facility [Member] | JPMORGAN CHASE BANK N.A. [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Maturity interest period, Variable Rate |  |  | 3 months |  |  |  |  |
TVN [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Income Taxes Receivable |  |  | $ 23,200,000 |  |  |  |  |
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% |  |  |  |  |
Loans Payable to Bank |  |  | $ 15,100,000 | 16,700,000 |  |  |  |
Debt Instrument, Basis Spread on Variable Rate |  |  | 1.30% |  |  |  |  |
Loans Backed By French Research And Development Tax Credit Receivables [Member] | TVN [Member] | Euribor Future [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Maturity interest period, Variable Rate |  |  | 1 month |  |  |  |  |
Loans From French Government For R&D Innovation Projects [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Loans Payable to Bank |  |  | $ 1,500,000 | 2,100,000 |  |  |  |
Convertible Note due 2024 [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  | 2.00% | 2.00% |  |  |  |  |
Debt Instrument, Face Amount |  | $ 115,500,000 | $ 115,500,000 |  |  |  |  |
Common Stock, Par Value Per Share | $ / shares |  | $ 0.001 |  |  |  |  |  |
Debt Instrument, Convertible, Conversion Ratio |  | 115.5001 |  |  |  |  |  |
Debt Conversion, Converted Instrument, Amount |  | $ 1,000 |  |  |  |  |  |
Debt Instrument, Convertible, Conversion Price | $ / shares |  | $ 8.66 |  |  |  |  |  |
Debt Instrument, Convertible, Carrying Amount of Equity Component |  | $ 24,900,000 |  |  |  |  |  |
Convertible Note due 2024 [Member] | Stock price greater or equal 130 percent of Note Conversion Price [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Convertible, Threshold Consecutive Trading Days | day |  | 30 |  |  |  |  |  |
Debt Instrument, Convertible, Threshold Trading Days | day |  | 20 |  |  |  |  |  |
Debt Instrument, Convertible, Threshold Percentage of Stock Price Trigger |  | 130.00% |  |  |  |  |  |
Convertible Note due 2024 [Member] | Note price less than 98 percent of stock price times conversion rate [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Conversion, Converted Instrument, Amount |  | $ 1,000 |  |  |  |  |  |
Debt Instrument, Convertible, Threshold Consecutive Trading Days | day |  | 5 |  |  |  |  |  |
Debt Instrument, Convertible, Threshold Trading Days | day |  | 5 |  |  |  |  |  |
Debt Instrument, Convertible, Threshold Percentage of Stock Price Trigger |  | 98.00% |  |  |  |  |  |
Convertible Note due 2020 [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Interest Rate, Stated Percentage |  |  | 4.00% |  |  | 4.00% |  |
Debt Instrument, Face Amount |  |  | $ 45,785,000 | $ 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 |  |
Debt Instrument, Repurchase Amount |  | $ 109,600,000 |  |  |  |  |  |
Debt Instrument, Convertible, Carrying Amount of Equity Component |  |  |  |  |  | $ 26,100,000 |  |
Reclassification from APIC to Convertible Debt in Mezzanine Equity |  |  | $ 2,400,000 |  |  |  |  |
Convertible Note due 2020 [Member] | Stock price greater or equal 130 percent of Note Conversion Price [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Convertible, Threshold Consecutive Trading Days | day |  |  | 30 |  |  |  |  |
Debt Instrument, Convertible, Threshold Trading Days | day |  |  | 20 |  |  |  |  |
Debt Instrument, Convertible, Threshold Percentage of Stock Price Trigger |  |  | 130.00% |  |  |  |  |
Convertible Note due 2020 [Member] | Note price less than 98 percent of stock price times conversion rate [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt Instrument, Convertible, Threshold Consecutive Trading Days | day |  |  |  |  |  | 5 |  |
Debt Instrument, Convertible, Threshold Trading Days | day |  |  |  |  |  | 5 |  |
Debt Instrument, Convertible, Threshold Percentage of Stock Price Trigger |  |  |  |  |  | 98.00% |  |
Convertible Debt [Member] | Convertible Note due 2020 [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Loss on debt extinguishment |  | 5,700,000 |  |  |  |  |  |
Convertible Debt [Member] | Long-term Debt [Member] | Convertible Note due 2020 [Member] | Privately Negotiated Transactions [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Extinguishment of Debt, Amount |  | 82,500,000 |  |  |  |  |  |
Convertible Debt [Member] | Additional Paid-in Capital [Member] | Convertible Note due 2020 [Member] | Privately Negotiated Transactions [Member] |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Extinguishment of Debt, Amount |  | $ 27,100,000 |  |  |  |  |  |
[1] | Loans backed by French R&D tax credit receivables were $15.1 million and $16.7 million as of December 31, 2019 and 2018, respectively. As of December 31, 2019, the French Subsidiary had an aggregate of $23.2 million of R&D tax credit receivables from the French government from 2020 through 2023. (See Note 10, “Certain 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 plus 1.3% and mature between 2020 through 2022. The remaining loans of $1.5 million and $2.1 million as of December 31, 2019 and 2018, respectively, primarily relate to financial support from French government agencies for R&D innovation projects at minimal interest rates, and the loans outstanding at December 31, 2019 mature between 2020 through 2025.

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