XML 93 R70.htm IDEA: XBRL DOCUMENT
v3.21.1

Capital surplus (Tables) | 12 Months Ended
--- | ---
Dec. 31, 2020
Text block [abstract] |
Summary of Capital Surplus |
|  | 2018 |
|  | Share premium |  |  | Employee restricted shares |  |  | Others |  |  | Total |
|  | NT$000 |  |  | NT$000 |  |  | NT$000 |  |  | NT$000 |
January 1 |  |  | 5,873,743 |  |  |  | 390,401 |  |  |  | 7,304 |  |  |  | 6,271,448 |
Share-based payments |  |  | — |  |  |  | (7,967 | ) |  |  | — |  |  |  | (7,967 | )
Capital reduction |  |  | — |  |  |  | 72 |  |  |  | — |  |  |  | 72 |
December 31 |  |  | 5,873,743 |  |  |  | 382,506 |  |  |  | 7,304 |  |  |  | 6,263,553 |
|  | 2019 |
|  | Share premium |  |  | Employee restricted shares |  |  | Others |  |  | Total |
|  | NT$000 |  |  | NT$000 |  |  | NT$000 |  |  | NT$000 |
January 1 |  |  | 5,873,743 |  |  |  | 382,506 |  |  |  | 7,304 |  |  |  | 6,263,553 |
Share-based payments |  |  | — |  |  |  | (412 | ) |  |  | — |  |  |  | (412 | )
Cancellation of treasury stock |  |  | (199,501 | ) |  |  | (12,853 | ) |  |  | — |  |  |  | (212,354 | )
December 31 |  |  | 5,674,242 |  |  |  | 369,241 |  |  |  | 7,304 |  |  |  | 6,050,787 |
|  | 2020 |
|  | Share premium |  |  | Employee restricted shares |  |  | Others |  |  | Total |
|  | NT$000 |  |  | NT$000 |  |  | NT$000 |  |  | NT$000 |
January 1 |  |  | 5,674,242 |  |  |  | 369,241 |  |  |  | 7,304 |  |  |  | 6,050,787 |
Reclassifications |  |  | 369,241 |  |  |  | (369,241 | ) |  |  | — |  |  |  | — |
December 31 |  |  | 6,043,483 |  |  |  | — |  |  |  | 7,304 |  |  |  | 6,050,787 |

X
- Definition Components capital surplus. + References No definition available. + Details
Name: | imos_ComponentsCapitalSurplusExplanatory
Namespace Prefix: | imos_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Text block [abstract] + References No definition available. + Details
Name: | imos_TextBlockAbstract
Namespace Prefix: | imos_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration