Income Taxes	3 Months Ended
Mar. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Mattel’s benefit from income taxes was $2.7 million and $32.4 million for the three months ended March 31, 2018 and 2017, respectively. During the three months ended March 31, 2018 and 2017, Mattel recognized net discrete tax expense of $4.5 million and $0.5 million, respectively, primarily related to reassessments of prior years' tax liabilities and income taxes recorded on a discrete basis in various jurisdictions. In 2017, Mattel established a valuation allowance on its U.S. deferred tax assets and has provided no U.S. tax benefit for the three months ended March 31, 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 $28 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. On December 22, 2017, H.R.1, also known as the Tax Cuts and Jobs Act ("Tax Act" or "U.S. Tax Reform"), was enacted. The Securities Exchange Commission has issued guidance under Staff Accounting Bulletin 118 that allows for companies to provide provisional amounts for certain income tax effects of the Tax Act for which the company can provide a reasonable estimate. The guidance also provides that a company may not have the necessary information available, prepared, or analyzed for certain income tax effects of the Tax Act, in which case the company would not be expected to provide a provisional amount for those specific items. Additionally, the guidance allows for a measurement period of up to one year after the enactment date of the Tax Act to finalize the recording of the related tax impacts. As of December 31, 2017, Mattel reasonably estimated and recorded provisional amounts associated with the impact of the corporate tax rate change. Mattel has not made any additional measurement-period adjustments related to these items during the quarter. Mattel continues to gather additional information to complete the accounting for these items and will complete our accounting within the prescribed measurement period. Mattel has not yet been able to reasonably estimate the impact of the deemed repatriation of accumulated foreign earnings and no provisional adjustments have been recorded as of March 31, 2018. Mattel is continuing to evaluate the impact of this provision of the Tax Act and will complete the accounting for this item within the prescribed measurement period. In addition, Mattel may re-evaluate the intentions related to the indefinite reinvestment assertion, as the incremental tax expense from repatriation of foreign earnings may be significantly less under the Tax Act. In January 2018, the Financial Accounting Standards Board ("FASB") issued guidance stating that a company must make an accounting policy election of either (i) treating taxes due on future U.S. inclusions in taxable income related to Global Intangible Low-Taxed Income ("GILTI") as a current-period expense when incurred (the "period cost method") or (ii) factoring such amounts into a company’s measurement of its deferred taxes (the "deferred method"). Mattel has elected the period cost method and has considered the estimated 2018 GILTI impact in its 2018 tax expense. On January 1, 2018, Mattel adopted ASU 2016-16, Intra-Entity Transfers of Assets Other Than Inventory, which required Mattel to recognize the income tax effects of intercompany sales and transfers of assets other than inventory in the period in which the transfer occurs. Previously, the income tax effect of intercompany transfers of assets was deferred until the asset was sold to an outside party or otherwise recognized (e.g., depreciated, amortized, impaired). The new guidance requires Mattel to defer only the income tax effects of intercompany transfers of inventory. A cumulative effect adjustment of approximately $9 million was recorded as an increase to beginning retained earnings in the first quarter of 2018.

Income Taxes

Mattel’s benefit from income taxes was $2.7 million and $32.4 million for the three months ended March 31, 2018 and 2017, respectively. During the three months ended March 31, 2018 and 2017, Mattel recognized net discrete tax expense of $4.5 million and $0.5 million, respectively, primarily related to reassessments of prior years' tax liabilities and income taxes recorded on a discrete basis in various jurisdictions. In 2017, Mattel established a valuation allowance on its U.S. deferred tax assets and has provided no U.S. tax benefit for the three months ended March 31, 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 $28 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.

On December 22, 2017, H.R.1, also known as the Tax Cuts and Jobs Act ("Tax Act" or "U.S. Tax Reform"), was enacted. The Securities Exchange Commission has issued guidance under Staff Accounting Bulletin 118 that allows for companies to provide provisional amounts for certain income tax effects of the Tax Act for which the company can provide a reasonable estimate. The guidance also provides that a company may not have the necessary information available, prepared, or analyzed for certain income tax effects of the Tax Act, in which case the company would not be expected to provide a provisional amount for those specific items. Additionally, the guidance allows for a measurement period of up to one year after the enactment date of the Tax Act to finalize the recording of the related tax impacts.

As of December 31, 2017, Mattel reasonably estimated and recorded provisional amounts associated with the impact of the corporate tax rate change. Mattel has not made any additional measurement-period adjustments related to these items during the quarter. Mattel continues to gather additional information to complete the accounting for these items and will complete our accounting within the prescribed measurement period.

Mattel has not yet been able to reasonably estimate the impact of the deemed repatriation of accumulated foreign earnings and no provisional adjustments have been recorded as of March 31, 2018. Mattel is continuing to evaluate the impact of this provision of the Tax Act and will complete the accounting for this item within the prescribed measurement period. In addition, Mattel may re-evaluate the intentions related to the indefinite reinvestment assertion, as the incremental tax expense from repatriation of foreign earnings may be significantly less under the Tax Act.

In January 2018, the Financial Accounting Standards Board ("FASB") issued guidance stating that a company must make an accounting policy election of either (i) treating taxes due on future U.S. inclusions in taxable income related to Global Intangible Low-Taxed Income ("GILTI") as a current-period expense when incurred (the "period cost method") or (ii) factoring such amounts into a company’s measurement of its deferred taxes (the "deferred method"). Mattel has elected the period cost method and has considered the estimated 2018 GILTI impact in its 2018 tax expense.

On January 1, 2018, Mattel adopted ASU 2016-16, Intra-Entity Transfers of Assets Other Than Inventory, which required Mattel to recognize the income tax effects of intercompany sales and transfers of assets other than inventory in the period in which the transfer occurs. Previously, the income tax effect of intercompany transfers of assets was deferred until the asset was sold to an outside party or otherwise recognized (e.g., depreciated, amortized, impaired). The new guidance requires Mattel to defer only the income tax effects of intercompany transfers of inventory. A cumulative effect adjustment of approximately $9 million was recorded as an increase to beginning retained earnings in the first quarter of 2018.