Employee Benefit Plans - Narrative (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2017
Employee Benefits Disclosure [Line Items]
Accumulated benefit obligation of defined benefit pension plans	$ 595.4	$ 652.7
Total estimated cash contributions to be made during the next fiscal year for defined benefit pension and postretirement benefit plans	$ 6.0
Percentage of domestic defined benefit pension plan assets to total defined benefit pension plan assets	76.00%
Percentage of total membership in pension plan insured				40.00%
Percentage limitation of an employee's total account balance that may be allocated to the Mattel Stock Fund in the Mattel, Inc. Personal Investment Plan	25.00%
Liability for deferred compensation and excess benefit plans	$ 62.8	59.9
Cash surrender value of life insurance policies	88.6	79.9
Expense for incentive compensation plans	$ 137.1	$ 122.5	$ 119.5
Defined benefit pension plans
Employee Benefits Disclosure [Line Items]
Long-term rate of return on plan assets used to determine net periodic benefit cost for domestic defined benefit pension plans	5.00%	5.50%	6.00%
U.S. equity securities
Employee Benefits Disclosure [Line Items]
Target allocation for domestic defined benefit pension plan assets	42.00%
Non U.S. Equity Securities
Employee Benefits Disclosure [Line Items]
Target allocation for domestic defined benefit pension plan assets	28.00%
Long-Term Bond Securities
Employee Benefits Disclosure [Line Items]
Target allocation for domestic defined benefit pension plan assets	20.00%
US Treasury Securities
Employee Benefits Disclosure [Line Items]
Target allocation for domestic defined benefit pension plan assets	10.00%