Basis of Presentation	6 Months Ended
Basis of Presentation	Jun. 30, 2021
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited consolidated financial statements and related disclosures have been prepared in accordance with accounting principles generally accepted in the United States of America ("GAAP") applicable to interim financial information and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. In the opinion of management, all adjustments, consisting of only those of a normal recurring nature, considered necessary for a fair statement of the financial position and interim results of Mattel, Inc. and its subsidiaries ("Mattel") as of and for the periods presented have been included. The December 31, 2020 balance sheet data was derived from audited financial statements; however, the accompanying interim notes to the consolidated financial statements do not include all of the annual disclosures required by GAAP. As Mattel's business is seasonal, results for interim periods are not necessarily indicative of those that may be expected for a full year. The financial information included herein should be read in conjunction with Mattel's consolidated financial statements and related notes in the 2020 Annual Report on Form 10-K. Certain prior period amounts have been reclassified to conform to the current period presentation. Revision of Previously Issued Consolidated Financial Statements During the quarter ended June 30, 2021, Mattel identified a misstatement in its accounting for inventory tooling expenses, which were expensed to cost of sales rather than first being capitalized into the cost of inventory, which resulted in an understatement of inventory balances and a misstatement of cost of sales. Mattel also identified a misstatement related to the timing of disbursements for certain capital expenditures, that resulted in a cash flow misclassification between operating activities and investing activities. Mattel evaluated the misstatements and concluded that the misstatements were not material, either individually or in aggregate, to its current or previously issued consolidated financial statements. To correct the immaterial misstatements, Mattel has elected to revise its previously issued consolidated financial statements as of December 31, 2020 and 2019, and for each of the three years ended December 31, 2020, 2019, and 2018 and its unaudited consolidated financial statements as of and for the quarters and year-to-date periods ended March 31, 2020 and 2021, June 30, 2020, and September 30, 2020. The revision of the historical consolidated financial statements also includes the correction of other immaterial misstatements in its consolidated statement of operations that Mattel had previously recorded as out of period adjustments, as well as other previously identified balance sheet misclassifications. Mattel had previously determined that these misstatements did not, either individually or in the aggregate, result in a material misstatement of its previously issued consolidated financial statements and reached the same conclusion when aggregating with the recently identified misstatements. Further information regarding the misstatements and related revision is included in Note 24 - Revision for Immaterial Misstatements. Accordingly, the accompanying financial statements and relevant footnotes to the consolidated financial statements in this Quarterly Report on Form 10-Q have been revised to correct for such misstatements. Mattel will present the revision of its previously issued consolidated financial statements as of December 31, 2020 and for the years ended December 31, 2020 and 2019 in connection with the future filing of its 2021 Annual Report on Form 10-K. Additionally, Mattel will present the revision of its previously issued consolidated financial statements as of and for the three months ended March 31, 2021 and as of and for the three and nine months ended September 30, 2020 in connection with the future filings of its Quarterly Reports on Form 10-Q.