Segment Information - Worldwide Revenues by Categories (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Segment Reporting, Asset Reconciling Item [Line Items]
Revenues	$ 1,473,705	$ 1,481,557	$ 860,063	$ 689,246	$ 1,524,281	$ 1,437,451	$ 844,706	$ 708,372	$ 4,504,571	$ 4,514,810	$ 4,881,493
Operating Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Revenues									5,064,574	5,075,529	5,514,125
Operating Segments | Dolls
Segment Reporting, Asset Reconciling Item [Line Items]
Revenues									1,724,008	1,730,907	1,725,865
Operating Segments | Infant, Toddler, and Preschool
Segment Reporting, Asset Reconciling Item [Line Items]
Revenues									1,257,646	1,417,820	1,677,223
Operating Segments | Vehicles
Segment Reporting, Asset Reconciling Item [Line Items]
Revenues									1,101,338	1,065,452	1,242,790
Operating Segments | Action Figures, Building Sets, and Games
Segment Reporting, Asset Reconciling Item [Line Items]
Revenues									981,582	861,350	868,247
Sales adjustments
Segment Reporting, Asset Reconciling Item [Line Items]
Revenues									$ (560,003)	$ (560,719)	$ (632,632)