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Equity - Summary of Capital Surplus (Detail) $ in Thousands, $ in Thousands | Dec. 31, 2018 USD ($) | Dec. 31, 2018 TWD ($) | Dec. 31, 2017 TWD ($)
--- | --- | --- | ---
Disclosure of classes of share capital [abstract] |  |  |
Issuance of ordinary shares | $ 421,640 | $ 12,906,401 | $ 21,553,853
Merger by share exchange | 3,844,942 | 117,693,658 |
Conversion of bonds payable |  |  | 1,930,066
Difference between consideration and the carrying amount of the subsidiaries' net assets during actual disposal or acquisition | 197,128 | 6,034,102 | 7,176,958
Capital surplus deficit distributed as cash dividends | 4,463,710 | 136,634,161 | 30,660,877
Changes in percentage of ownership interest in subsidiaries | 121,768 | 3,727,336 | 6,084,895
Treasury share transactions | 5,957 | 182,354 | 1,151,345
Exercised employee share options | 44,642 | 1,366,480 | 1,089,178
Expired share options (Notes 22 and 29) | 21,103 | 645,978 | 223,454
Share of changes in capital surplus of associates | 2,847 | 87,136 | 83,733
Dividends that the claim period has elapsed and unclaimed by shareholders | 29 | 872 |
Capital surplus offset deficit | 196,346 | 6,010,156 | 8,632,605
Employee share options | 19,064 | 583,542 | 960,888
Equity component of convertible bonds |  |  | 214,022
Others | 1,594 | 48,805 | 155,936
Capital surplus for other purpose | 20,658 | 632,347 | 1,330,846
Capital surplus | $ 4,680,714 | $ 143,276,664 | $ 40,624,328

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