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