Business, Basis of Presentation and Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Business	*Business* MagnaChip Semiconductor Corporation (together with its subsidiaries, the “Company”) is a designer and manufacturer of analog and mixed-signal semiconductor platform solutions for communications, Internet of Things (“IoT”) applications, consumer, industrial and automotive applications. The Company provides technology platforms for analog, mixed signal, power, high voltage, non-volatile memory and Radio Frequency (“RF”) applications. The Company’s business is comprised of two operating segments: Foundry Services Group and Standard Products Group. The Company’s Foundry Services Group provides specialty analog and mixed-signal foundry services mainly for fabless and Integrated Device Manufacturer (“IDM”) semiconductor companies that primarily serve communications, IoT, consumer, industrial and automotive applications. The Company’s Standard Products Group is comprised of two business lines: Display Solutions and Power Solutions. The Company’s Display Solutions products provide panel display solutions to major suppliers of large and small rigid and flexible panel displays, and mobile, automotive applications and home appliances. The Company’s Power Solutions products include discrete and integrated circuit solutions for power management in communications, consumer and industrial applications.
Basis of Presentation	*Basis of Presentation* The accompanying unaudited interim consolidated financial statements of the Company have been prepared in accordance with generally accepted accounting principles in the United States of America (“US GAAP”). These interim consolidated financial statements include normal recurring adjustments and the elimination of all intercompany accounts and transactions which are, in the opinion of management, necessary to provide a fair statement of the Company’s financial condition and results of operations for the periods presented. These interim consolidated financial statements are presented in accordance with Accounting Standards Codification 270, “Interim Reporting” and, accordingly, do not include all of the information and note disclosures required by US GAAP for complete financial statements, except for the changes below. The results of operations for the three months ended March 31, 2018 are not necessarily indicative of the results to be expected for a full year or for any other periods. The December 31, 2017 balance sheet data was derived from the Company’s audited financial statements, but does not include all disclosures required by US GAAP. Upon the adoption of Accounting Standards Update No. 2014-09, “Revenue from Contracts with Customers (Topic 606)” (“ASU 2014-09”) effective on January 1, 2018 (the “new revenue standard”), the Company has updated its accounting policy for revenue recognition as detailed below. As the Company adopted the new revenue standard using the modified retrospective method, which allows the recognition of the cumulative effect of initially applying the new revenue standard as an adjustment to the Company’s equity as of January 1, 2018, the Company has not changed the comparative information within its interim consolidated financial statements for the three months ended March 31, 2017. The comparative information continues to be reported under the accounting standards in effect for that period.
Revenue Recognition	*Revenue Recognition* The Company recognizes revenue when it satisfies a performance obligation by transferring control over a product or service to a customer. Revenue is measured based on a consideration specified in a contract with a customer in exchange for such product or service. The Foundry Services Group of the Company manufactures products based on customers’ specific product designs. The Company recognizes revenue over time for those foundry products without alternative use where the Company has an enforceable right to payment for the related foundry services completed to date. The revenue recognized over time is in proportion of wafer manufacturing costs incurred relative to total estimated costs at completion to measure the Company’s performance to date. However, in certain circumstances, the Company may not have an enforceable right to payment for performed foundry services pursuant to a customer contract or an individual purchase order. In this situation, the Company recognizes revenue when a customer obtains control of the product, which is generally upon product shipment, delivery at the customer’s location or upon customer acceptance, depending on the terms of the arrangement. The Standards Products Group of the Company sells products manufactured based on the Company’s design. The Standard Products Group’s products are either standardized with an alternative use or the Company does not have an enforceable right to payment for the related manufacturing services completed to date. For those products, revenue is recognized when a customer obtains control of the product, which is generally upon product shipment, delivery at the customer’s location or upon customer acceptance, depending on the terms of the arrangement. A portion of the Company’s sales are made through distributors for which the Company applies the same revenue recognition guidance as described above. The Company defers recognition of revenue when it receives cash from certain customers and distributors for the sale of products prior to obtaining an enforceable right to payment for performance completed to date or control of the product being transferred to the customer. In accordance with revenue recognition guidance, any tax assessed by a governmental authority that is both imposed on and concurrent with a specific revenue-producing transaction, and that is collected by the Company from a customer, is excluded from revenue and presented in the statement of operations on a net basis. The Company provides a warranty, under which customers can return defective products. The Company estimates the costs related to those defective product returns and records them as a component of cost of sales. In addition, the Company offers sales returns (other than those that relate to defective products under warranty), cash discounts for early payments, volume rebate and certain allowances to its customers, including distributors. The Company records reserves for those returns, discounts and allowances as a deduction from sales, based on historical experience and other quantitative and qualitative factors. Substantially all of the Company’s contracts are one year or less in duration. The standard payment terms with customers is generally thirty to sixty days from the time of shipment, product delivery at the customer’s location or customer acceptance, depending on the terms of the related arrangement. In May 2014, the FASB issued ASU 2014-09. ASU 2014-09 supersedes the revenue recognition requirements in “Revenue Recognition (Topic 605)”, and requires entities to recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled to in exchange for those goods or services. ASU 2014-09 is effective for annual reporting periods beginning after December 15, 2017, including interim periods within that reporting period. The new guidance allows for the amendments to be applied either retrospectively to each prior reporting period presented (the “full retrospective method”) or retrospectively as a cumulative-effect adjustment as of the date of adoption (the “modified retrospective method”). In March 2016, the FASB issued ASU 2016-08, which clarifies the implementation guidance on principal versus agent considerations. In April 2016, the FASB issued ASU 2016-10, which clarifies identifying performance obligations and the licensing implementation guidance. In May 2016, the FASB issued ASU 2016-12, which improves certain aspects of ASC Topic 606 “Revenue from Contracts with Customers.” In December 2016, the FASB issued ASU 2016-20, which improves certain aspects of ASC Topic 606 “Revenue from Contracts with Customers.” The effective date and transition requirements for ASU 2016-08, ASU 2016-10, ASU 2016-12 and ASU 2016-20 are the same as the effective date and transition requirements of ASU 2014-09 (collectively, the “new revenue standard”).
Recent Accounting Pronouncements	*Recent Accounting Pronouncements* In February 2018, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update No. 2018-02 “Income Statement—Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income” (“ASU 2018-02”). ASU 2018-02 addresses the accounting issue pertaining to the deferred tax amounts that are “stranded” in accumulated other comprehensive income as a result of the Tax Cuts and Jobs Act. ASU 2018-02 is effective for interim and annual periods beginning after December 15, 2018 and interim periods within those fiscal years. The Company does not have deferred tax amounts recorded through accumulated other comprehensive income and thus does not expect that the adoption will have an impact on its consolidated financial statements. In August 2017, the FASB issued Accounting Standards Update No. 2017-12, “Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities” (“ASU 2017-12”). ASU 2017-12 provides new guidance about income statement classification and eliminates the requirement to separately measure and report hedge ineffectiveness. The entire change in fair value for qualifying hedge instruments included in the effectiveness will be recorded in other comprehensive income (OCI) and amounts deferred in OCI will be reclassified to earnings in the same income statement line item in which the earnings effect of the hedged item is reported. ASU 2017-12 is effective for interim and annual periods for the Company on January 1, 2019, with early adoption permitted. The Company is currently evaluating the impact of adoption of ASU 2017-12 on its consolidated financial statements. In July 2017, the FASB issued Accounting Standards Update No. 2017-11, “Earnings Per Share (Topic 260); Distinguishing Liabilities from Equity (Topic 480); Derivatives and Hedging (Topic 815)” (“ASU 2017-11”), which addresses the complexity of accounting for certain financial instruments with down round features. Down round features are features of certain equity-linked instruments (or embedded features) that result in the strike price being reduced on the basis of the pricing of future equity offerings. Current accounting guidance creates cost and complexity for entities that issue financial instruments (such as warrants and convertible instruments) with down round features that require fair value measurement of the entire instrument or conversion option. For public business entities, the amendments in ASU 2017-11 are effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. The Company is currently evaluating the impact of adoption of ASU 2017-11 on its consolidated financial statements. In February 2016, the FASB issued Accounting Standards Update No. 2016-02, “Leases (Topic 842)” (“ASU 2016-02”) in order to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet for those leases classified as operating leases under US GAAP. ASU 2016-02 requires that a lessee should recognize a liability to make lease payments and a right-of-use asset representing its right to use the underlying asset for the lease term on the balance sheet. ASU 2016-02 is effective for fiscal years beginning after December 15, 2018, including interim periods within those reporting periods using a modified retrospective approach and early adoption is permitted. In January 2018, The FASB issued Accounting Standards Update No 2018-01, “Leases (Topic 842) Land Easement Practical Expedient for Transition to Topic 842” (“ASU 2018-01”). ASU 2018-01 permits an entity to elect an optional transition practical expedient to not evaluate land easements that exist or expired before the entity’s adoption of 2016-02 and that were not accounted for as leases under previous lease guidance. The effective date and transition requirements for ASU 2018-01 and ASU 2016-02 are the same. The Company will adopt this standard on January 1, 2019. The Company is currently evaluating the potential impact of adopting this new guidance. In terms of the Company’s evaluation efforts, the Company has assigned internal resources in addition to the engagement of third party service providers to assist in its evaluation.
Recently Adopted Accounting Pronouncements - Compensation-Stock Compensation	In May 2017, the FASB issued Accounting Standards Update No. 2017-09, “Compensation-Stock Compensation (Topic 718): Scope of Modification Accounting” (“ASU 2017-09”). ASU 2017-09 provides clarity and reduces both (i) diversity in practice and (ii) cost and complexity when applying the guidance in Topic 718 to a change to the terms or conditions of a share-based payment award. The amendments in ASU 2017-09 provide guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting in Topic 718. The Company adopted ASU 2017-09 in the first quarter of 2018, and the adoption did not impact the Company’s consolidated financial statements.
Recently Adopted Accounting Pronouncements - Restricted Cash	In November 2016, the FASB issued ASU 2016-18, Statement of Cash Flows (Topic 230), Restricted Cash (“ASU 2016-18”). ASU 2016-18 clarifies certain existing principles in ASC 230, including providing additional guidance related to transfers between cash and restricted cash and how entities present, “net cash used in operating” and “net cash used in investing” in their statement of cash flows, the cash receipts and cash payments that directly affect the restricted cash accounts. The Company adopted ASU 2016-18 in the first quarter of 2018. As of December 31, 2016, the Company held $18,251 thousand of restricted cash in connection with an arrangement to sell the building that housed the Company’s legacy 6-inch fab. This restricted cash was not previously included within the consolidated statements of cash flows. As a result of adopting ASU 2016-18, the consolidated statement of cash flows for the three months ended March 31, 2017 was revised to include the impact of this restricted cash, resulting in a cash outflow of $1,809 thousand in operating cash flows, a cash outflow of $17,625 thousand in investing cash flows, and an increase of $1,183 thousand in cash, cash equivalents and restricted cash due to the effect of exchange rates, from what was previously reported. The Company did not hold restricted cash as of December 31, 2017 or March 31, 2018. As such, the adoption of ASU 2016-18 did not impact the Company’s consolidated balance sheets as of March 31, 2018 or December 31, 2017, or the consolidated statement of cash flows for the three months ended March 31, 2018.
Recently Adopted Accounting Pronouncements - Classification of Certain Cash Receipts and Cash Payments	In August 2016, the FASB issued Accounting Standards Update No. 2016-15, “Statement of Cash Flows (Topic 230), Classification of Certain Cash Receipts and Cash Payments” (“ASU 2016-15”). ASU 2016-15 reduces the existing diversity in practice in financial reporting across all industries by clarifying certain existing principles in ASC 230, Statement of Cash Flows (“ASC 230”), including providing additional guidance on how and what an entity should consider in determining the classification of certain cash flows. The Company adopted ASU 2016-15 in the first quarter of 2018, and the adoption of ASU 2016-15 did not impact the Company’s consolidated financial statements.