Accumulated Other Comprehensive Income (Loss) - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications	$ 1,929	$ 44,432
Amounts reclassified from accumulated other comprehensive income (loss)	5,351	3,433
Currency translation adjustments (loss) gain	7,280	47,865
Mattel163 Limited
Accumulated Other Comprehensive Income (Loss) [Line Items]
Amounts reclassified from accumulated other comprehensive income (loss)	2,700
Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications	(5,954)	53,618
Amounts reclassified from accumulated other comprehensive income (loss)	2,717	0
Currency translation adjustments (loss) gain	(3,237)	53,618
Derivative Instruments:
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications	7,129	(9,223)
Amounts reclassified from accumulated other comprehensive income (loss)	1,821	2,185
Currency translation adjustments (loss) gain	$ 8,950	$ (7,038)