Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2018	Feb. 08, 2019	Jun. 30, 2018
Document And Entity Information [Abstract]
Document Type	10-K/A
Amendment Flag	true
Amendment Description	This Amendment No. 1 to Form 10-K (this "Amendment" or "Form 10-K/A") amends the Annual Report on Form 10-K for the year ended December 31, 2018 originally filed with the Securities and Exchange Commission ("SEC") on February 22, 2019 (the "Original Filing") by Mattel, Inc. (the "Company," "Mattel," "we," "our" or "us"). The purpose of this Amendment is to restate the Company’s previously issued unaudited consolidated financial statements as of and for the three and nine month periods ended September 30, 2017, respectively, and the Company’s previously reported unaudited consolidated financial information for the three months ended December 31, 2017, to correct for material tax misstatements.  In connection with such restatement, the Company has also elected to revise the Company’s previously issued consolidated financial statements as of December 31, 2018 and 2017 and for each of the three years in the period ended December 31, 2018, and relevant interim periods, to correct for other misstatements which the Company has determined to be immaterial, both individually and in the aggregate.
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Entity Registrant Name	MATTEL INC /DE/
Entity Central Index Key	0000063276
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Emerging Growth Company	false
Small Business	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		345,396,232
Entity Public Float			$ 5,650,844