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Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
Tax Credit Carryforward [Line Items] |  |  |
Change in valuation allowance | $ 2,253 | $ 515 | $ 1,075
Income tax holiday description | Profits generated from certain products of SMI Taiwan are exempted from income tax for five years beginning January 1, 2010 and January 1, 2012. |  |
Accumulated undistributed earnings from a foreign subsidiary | $ 242,000 |  |
Deferred tax liability | 0 |  |
Unrecognized tax benefits that would affect effective tax rate | 5,639 |  |
Total amount of interest expense and penalties | 363 | 343 | $ 627
Total amount of accrued interest and penalties | 1,977 | $ 1,674 |
Federal |  |  |
Tax Credit Carryforward [Line Items] |  |  |
Net operating loss carryforwards for income tax purposes | $ 9,427 |  |
Federal net operating loss carryforwards expiration year | 2035 |  |
Research And Development | Federal |  |  |
Tax Credit Carryforward [Line Items] |  |  |
Deferred tax assets tax credit carryforwards | $ 2,444 |  |
Tax credit carryforward expiration year for federal | 2035 |  |
Research And Development | State |  |  |
Tax Credit Carryforward [Line Items] |  |  |
Deferred tax assets tax credit carryforwards | $ 1,711 |  |
Tax credit carryforward expiration year for state | No expiration date |  |
Taiwan |  |  |
Tax Credit Carryforward [Line Items] |  |  |
Income tax exemption term | 5 years |  |
FCI | Research And Development |  |  |
Tax Credit Carryforward [Line Items] |  |  |
Deferred tax assets tax credit carryforwards | $ 4,139 |  |
FCI | Research And Development | Minimum |  |  |
Tax Credit Carryforward [Line Items] |  |  |
Tax credit carryforward expiration year for federal | 2015 |  |
FCI | Research And Development | Maximum |  |  |
Tax Credit Carryforward [Line Items] |  |  |
Tax credit carryforward expiration year for federal | 2019 |  |

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