Income Taxes	9 Months Ended
Income Taxes	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Mattel's provision for income taxes was $31.4 million and $46.2 million for the three and nine months ended September 30, 2019, respectively, as compared to a provision for income taxes of $66.3 million and $71.6 million for the three and nine months ended September 30, 2018, respectively. During the three and nine months ended September 30, 2019, Mattel recognized a net discrete tax expense of $0.1 million and a net discrete tax benefit of $1.1 million, respectively, as compared to a net discrete tax expense of $42.1 million and $44.3 million for the three and nine months ended September 30, 2018, respectively. For the three months ended September 30, 2019, Mattel recognized discrete tax expense of $13.5 million related to reassessments of prior years' tax liabilities and income taxes recorded on a discrete basis in various jurisdictions, offset by a $13.4 million tax benefit related to the reassessment of the future realizability of certain foreign deferred tax assets. For the three months ended September 30, 2018, Mattel recognized discrete tax expense primarily related to the provisional tax expense of $9.3 million for deemed repatriation of accumulated foreign earnings (net of related valuation allowance change), $14.6 million related to changes to the indefinite reinvestment assertion, and $17.8 million net tax expense related to reassessments of prior years' tax liabilities and income taxes recorded on a discrete basis in various jurisdictions. For the nine months ended September 30, 2019, Mattel recognized a discrete tax benefit of $13.4 million related to the reassessment of the future realizability of certain foreign deferred tax assets, offset by discrete tax expense of $12.3 million related to reassessments of prior years' tax liabilities and income taxes recorded on a discrete basis in various jurisdictions. For the nine months ended September 30, 2018, Mattel recognized provisional tax expense of $9.3 million for deemed repatriation of accumulated foreign earnings (net of related valuation allowance change), discrete tax expense from changes to the indefinite reinvestment assertion of $14.6 million, and net discrete tax expense from reassessments of prior years' tax liabilities and income taxes recorded on a discrete basis in various jurisdictions of $20.4 million. As a result of the establishment of a valuation allowance on U.S. deferred tax assets in 2017, there was no U.S. tax benefit provided for U.S. losses during the three and nine months ended September 30, 2019 and 2018. In the normal course of business, Mattel is regularly audited by federal, state, and foreign tax authorities. Based on the current status of federal, state, and foreign audits, Mattel believes it is reasonably possible that in the next twelve months, the total unrecognized tax benefits could decrease by approximately $8 million related to the settlement of tax audits and/or the expiration of statutes of limitations. The ultimate settlement of any particular issue with the applicable taxing authority could have a material impact on Mattel's consolidated financial statements. Mattel adopted ASU 2018-02, Income Statement - Reporting Comprehensive Income: Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income on January 1, 2019. Under the Tax Cuts and Jobs Act (the "U.S. Tax Act"), deferred taxes were adjusted to reflect the reduction of the federal income tax rate to the newly enacted federal income tax rate, which left the tax effects on items within accumulated other comprehensive income (loss) stranded at historical tax rates. ASU 2018-02 permits the reclassification of disproportionate tax effects in accumulated other comprehensive income (loss) caused by the U.S. Tax Act to retained earnings. Mattel elected not to reclassify income tax effects related to the U.S. Tax Act out of accumulated other comprehensive loss and into retained earnings. Mattel releases tax effects from accumulated other comprehensive loss utilizing the portfolio approach with respect to pension and postretirement benefit plan obligations.