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Income Taxes - Additional Information (Detail) - USD ($) | 3 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Dec. 31, 2017 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Income Tax Disclosure [Line Items] |  |  |  |  |
Tax cuts and jobs act, incomplete accounting, estimated income tax expense | $ 11,900,000 |  |  |  |
Tax cuts and jobs act, incomplete accounting, estimated write-down of deferred tax assets | 9,200,000 |  |  |  |
Tax cuts and jobs act, incomplete accounting, change in tax rate estimate income tax expense related to unrepatriated foreign earnings | 2,700,000 |  |  |  |
Tax cuts and jobs act, complete accounting, income tax expense (benefit) |  |  | $ (4,000,000.0) |  |
Deferred tax benefit recorded as an adjustment to other comprehensive income |  | $ 400,000 | 2,800,000 |  |
Deferred tax assets, gross |  | 56,177,000 |  |  |
Valuation allowance established against deferred tax assets |  | 48,616,000 |  |  |
Deferred tax assets, state research and development credits |  | 12,171,000 | 17,495,000 |  |
Net of deferred tax liabilities |  | 7,561,000 | 37,187,000 |  |
Foreign and domestic loss carry-forwards, research and development tax credits, unamortized research and development cost and state credit carry-forwards |  | $ 41,300,000 | 28,800,000 |  |
Operating loss carry forwards expiration year |  | 2029 |  |  |
Deferred tax assets |  | $ 20,101,000 | 47,233,000 |  |
Cash and cash equivalents |  | 73,773,000 | 105,504,000 |  |
Short-term investments |  | 33,243,000 | 3,246,000 |  |
Short-term liquidity amount |  | 107,000,000.0 | 108,700,000 |  |
Income tax benefit (expense) from stock options exercised adjustment to equity |  | 0 | 0 | $ 0 |
Unrecognized tax benefits | 2,366,000 | 1,487,000 | 1,868,000 | 2,366,000 | $ 2,226,000
Unrecognized tax benefits, effective tax rate | 2,200,000 | 1,400,000 | 1,700,000 | 2,200,000 |
Accrued interest and penalties | $ 800,000 | 500,000 | 700,000 | $ 800,000 |
Foreign Subsidiaries [Member] |  |  |  |  |
Income Tax Disclosure [Line Items] |  |  |  |  |
Short-term liquidity amount |  | $ 52,300,000 | $ 87,100,000 |  |
Short-term liquidity, in percentage |  | 48.90% | 80.10% |  |
Operating Losses Expiration Between 2020 and 2039 [Member] |  |  |  |  |
Income Tax Disclosure [Line Items] |  |  |  |  |
Deferred tax assets |  | $ 19,100,000 |  |  |
Minimum [Member] |  |  |  |  |
Income Tax Disclosure [Line Items] |  |  |  |  |
Operating loss carry forwards expiration year |  | 2020 |  |  |
Maximum [Member] |  |  |  |  |
Income Tax Disclosure [Line Items] |  |  |  |  |
Operating loss carry forwards expiration year |  | 2039 |  |  |
Domestic [Member] |  |  |  |  |
Income Tax Disclosure [Line Items] |  |  |  |  |
Deferred tax assets, gross |  | $ 46,266,000 |  |  |
Valuation allowance established against deferred tax assets |  | 46,266,000 |  |  |
Valuation allowance established against deferred tax assets |  | 42,800,000 |  |  |
State And Foreign Country [Member] |  |  |  |  |
Income Tax Disclosure [Line Items] |  |  |  |  |
Deferred tax assets, state research and development credits |  | $ 5,800,000 |  |  |

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