Segment Information - Worldwide Revenues by Brand Category (Detail) - USD ($) $ in Thousands	3 Months Ended								9 Months Ended	12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Sep. 30, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ 1,524,281	$ 1,437,451	$ 844,706	$ 708,372	$ 1,606,915	$ 1,560,983	$ 976,177	$ 737,418	$ 3,274,578	$ 4,514,810	$ 4,881,493	$ 5,453,150
Barbie
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues										1,088,953	954,892	971,795
Hot Wheels
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues										834,058	777,341	796,969
Fisher-Price and Thomas & Friends
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues										1,185,669	1,370,543	1,546,111
American Girl
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues										342,442	473,302	592,118
Toy Box
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues										1,624,407	1,938,047	2,166,721
Reconciling Adjustments
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues										$ (560,719)	$ (632,632)	$ (620,564)