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Shareholders' Equity - Additional Information (Detail) - $ / shares |  |  | 3 Months Ended | 12 Months Ended
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Oct. 24, 2016 | Nov. 02, 2015 | Dec. 31, 2016 | Sep. 30, 2016 | Jun. 30, 2016 | Mar. 31, 2016 | Dec. 31, 2015 | Sep. 30, 2015 | Jun. 30, 2015 | Mar. 31, 2015 | Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014
Retained Earnings Adjustments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Dividend distribution allowance description |  |  |  |  |  |  |  |  |  |  | SMI Taiwan subsidiary may only distribute dividends after it has made allowances as determined under ROC GAAP at each year-end for a. Payment of taxes; b. Recovery of prior years' deficits, if any; c. 10% of remaining balance after deduction for a and b as legal reserve; d. Special reserve based on relevant laws or regulations or 10% of remaining balance for deduction from above a to c as special reserve when necessary. |  |
Dividend declared | $ 0.20 | $ 0.15 | $ 0.0500 | $ 0.0375 | $ 0.0375 | $ 0.0375 | $ 0.0375 | $ 0.0375 | $ 0.0375 | $ 0.0375 | $ 0.20 | $ 0.2625 | $ 0.15
American Depositary Shares |  |  |  |  |  |  |  |  |  |  |  |  |
Retained Earnings Adjustments [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |
Dividend declared | $ 0.8 | $ 0.6 |  |  |  |  |  |  |  |  |  |  |

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- Definition Aggregate dividends declared during the period for each share of common stock outstanding. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 + Details
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- Definition Description of dividends paid, restrictions on dividend payments, statutory capital and surplus amounts, requirements and future requirements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 505 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6486098&loc=d3e24708-158529 + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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