| Cover Page - USD ($) | 12 Months Ended | ||
| Dec. 31, 2020 | Apr. 26, 2021 | Jun. 30, 2020 | |
| Document Information [Line Items] | |||
| Document Type | 10-K/A | ||
| Amendment Flag | true | ||
| Amendment Description | Explanatory Note Magnachip Semiconductor Corporation (“MagnaChip,” the “Company,” “we,” “us,” or “our”) is filing this Amendment No. 1 on Form 10-K/A (this “Amendment” or this “Report”) to amend the Annual Report on Form 10-K for the year ended December 31, 2020, originally filed with the Securities and Exchange Commission (the “SEC”) on March 9, 2021 (the “Original 10-K Filing”), solely for the purpose of presenting the information required by Part III of Form 10-K. Such information was previously omitted from the Original 10-K Filing in reliance on General Instruction G(3) to Form 10-K, which permits the information required by Part III of Form 10-K to be incorporated in the Form 10-K by reference to the definitive proxy statement for the 2021 Annual Meeting of Stockholders if such proxy statement is filed no later than 120 days after the fiscal year end. We are filing this Amendment to to present the information required by Part III of Form 10 K, as we will not file our definitive proxy statement within 120 days of the end of our fiscal year ended December 31, 2020. The reference on the cover of the Original 10-K Filing to the incorporation by reference to portions of our definitive proxy statement into Part III of the Original 10-K Filing is hereby deleted. In accordance with Rule 12b-15 under the Securities Exchange Act of 1934, as amended (the “Exchange Act”), Part III, Items 10 through 14 of the Original 10-K Filing are hereby amended and restated in their entirety. In addition, we are also including Exhibits 31.3 and 31.4 required by the filing of this Amendment and have consequently amended and restated Part IV, Item 15 of the Original 10-K Filing as set forth herein. Because this Amendment does not contain any financial statements nor does this Amendment contain or amend any disclosure with respect to Items 307 and 308 of Regulation S-K, paragraphs 3, 4 and 5 of the certifications contained in Exhibits 31.3 and 31.4 have been omitted. Because no financial statements are contained in this Amendment, we are not including certifications pursuant to 18 U.S.C. 1350. This Amendment does not amend or otherwise update any other information in the Original 10-K Filing. Accordingly, this Amendment should be read in conjunction with the Original 10-K Filing and with our filings with the SEC subsequent to the Original 10-K Filing. | ||
| Document Period End Date | Dec. 31, 2020 | ||
| Document Fiscal Year Focus | 2020 | ||
| Document Fiscal Period Focus | FY | ||
| Entity Registrant Name | Magnachip Semiconductor Corporation | ||
| Entity Central Index Key | 0001325702 | ||
| Current Fiscal Year End Date | --12-31 | ||
| Entity Well-known Seasoned Issuer | No | ||
| Entity Voluntary Filers | No | ||
| Entity Current Reporting Status | Yes | ||
| Entity Interactive Data Current | Yes | ||
| Entity Filer Category | Accelerated Filer | ||
| Entity Public Float | $ 332,177,863.40 | ||
| Entity Small Business | false | ||
| Entity Emerging Growth Company | false | ||
| Entity Shell Company | false | ||
| Entity Incorporation, State or Country Code | DE | ||
| Title of 12(b) Security | Common Stock | ||
| Trading Symbol | MX | ||
| Security Exchange Name | NYSE | ||
| Entity Common Stock, Shares Outstanding | 46,333,946 | ||
| Entity File Number | 001-34791 | ||
| Entity Tax Identification Number | 83-0406195 | ||
| Entity Address, Address Line One | c/o MagnaChip Semiconductor S.A. 1 | ||
| Entity Address, City or Town | Allée Scheffer | ||
| Entity Address, Postal Zip Code | L-2520 | ||
| City Area Code | 352 | ||
| Local Phone Number | 45-62-62 | ||
| Document Annual Report | true | ||
| Document Transition Report | false | ||
| Entity Address, Country | LU | ||
| ICFR Auditor Attestation Flag | true |
