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Equity Transaction with Non-controlling Interests - Additional Information (Detail) $ / shares in Units, $ / shares in Units, shares in Thousands, $ in Thousands, $ in Thousands |  | 1 Months Ended | 12 Months Ended |  |  |  |  |  |  |  |
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Jan. 01, 2018 | Aug. 31, 2018 USD ($) | Jul. 31, 2018 $ / shares | Jul. 31, 2018 $ / shares | Mar. 31, 2018 USD ($) | Jan. 31, 2018 $ / shares shares | Jan. 31, 2017 TWD ($) | Feb. 29, 2016 shares | Feb. 28, 2016 TWD ($) $ / shares shares | Jan. 31, 2016 | Dec. 31, 2018 USD ($) $ / shares shares | Dec. 31, 2018 TWD ($) shares | Sep. 30, 2018 USD ($) | Sep. 30, 2018 TWD ($) | Aug. 31, 2018 TWD ($) | Mar. 31, 2018 TWD ($) | Dec. 31, 2017 TWD ($) | Oct. 13, 2017 shares | Jul. 13, 2017 shares | Dec. 31, 2016 TWD ($)
Increase (decrease) in capital surplus |  | $ 311 |  |  |  |  |  |  |  |  |  |  |  |  | $ 9,530 |  |  |  |  |
Sale of shares | shares |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 323,094 | 101,164 |
Sale of shares per share | $ / shares |  |  |  |  |  |  |  |  |  |  | $ 10 |  |  |  |  |  |  |  |  |
Cash capital increase [member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Sale of shares | shares |  |  |  |  |  |  |  |  |  |  | 300,000 | 300,000 |  |  |  |  |  |  |  |
Sale of shares per share | $ / shares |  |  |  |  |  |  |  |  |  |  | $ 34.3 |  |  |  |  |  |  |  |  |
USI Enterprise Limited [member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of shares repurchased | shares |  |  |  |  |  |  |  | 4,501 |  |  |  |  |  |  |  |  |  |  |  |
Percentage of increase in shareholdings | 96.90% |  |  |  |  | 98.60% |  | 98.80% |  | 96.70% |  |  |  |  |  |  |  |  |  |
Increase (decrease) in capital surplus |  |  |  |  | $ (36,839) |  |  |  |  |  |  |  |  |  |  | $ (1,127,632) |  |  |  | $ (1,912,887)
Number of shares approved for repurchase | shares |  |  |  |  |  | 3,738 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Shares repurchase price per share | $ / shares |  |  |  |  |  | $ 17.49 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Universal Global Scientific Industrial Co., Ltd. [member] | USI [member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Increase (decrease) in capital surplus | $ |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ (20,552)
Sale of shares | shares |  |  |  |  |  |  |  |  | 39,603 |  |  |  |  |  |  |  |  |  |  |
Sale of shares per share | $ / shares |  |  |  |  |  |  |  |  | $ 20 |  |  |  |  |  |  |  |  |  |  |
Proceeds from issuance of shares | $ |  |  |  |  |  |  |  |  | $ 792,064 |  |  |  |  |  |  |  |  |  |  |
Percentage of decrease in shareholdings |  |  |  |  |  |  |  |  | 76.50% | 99.00% |  |  |  |  |  |  |  |  |  |
USI [member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of increase in shareholdings |  |  |  |  |  |  | 75.20% |  |  |  |  |  |  |  |  |  |  |  |  |
Increase (decrease) in capital surplus | $ |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 3,055 |  |  |
Cash capital increase amount | $ |  |  |  |  |  |  | $ 1,000,000 |  |  |  |  |  |  |  |  |  |  |  |  |
Ordinary shares outstanding acquired price | (per share) |  |  | $ 18.0 | $ 0.6 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
USI [member] | Cash capital increase [member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of increase in shareholdings |  |  |  |  |  |  | 75.70% |  |  |  |  |  |  |  |  |  |  |  |  |
ASEN [member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Increase (decrease) in capital surplus |  |  |  |  |  |  |  |  |  |  | $ 36,410 | $ 1,114,504 | $ (56,756) | $ (1,737,315) |  |  |  |  |  |
Amount of shares transferred |  |  |  |  | $ 127,113 |  |  |  |  |  |  |  |  |  |  | $ 3,871,862 |  |  |  |
Percentage of shareholdings |  | 30.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Amount of shareholdings | $ |  | $ 95,335 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
ASEN [member] | Bottom of range [member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of increase in ownership |  |  |  |  | 60.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of decrease in ownership |  | 70.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
ASEN [member] | Top of range [member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of increase in ownership |  |  |  |  | 100.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percentage of decrease in ownership |  | 100.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
USI INC [member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Increase (decrease) in capital surplus |  | $ (920) |  |  |  |  |  |  |  |  |  |  |  |  | $ (28,152) |  |  |  |  |
Ordinary shares outstanding acquired price | (per share) |  |  | $ 35.0 | $ 1.1 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |

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