Summary of Significant Accounting Policies - Reconciliation of Weighted Average Shares Used in Computation of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ 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
Accounting Policies [Abstract]
Net loss	$ (20,181)	$ 16,414	$ (22,485)	$ (29,127)	$ (3,343)	$ 15,699	$ (18,588)	$ (36,193)	$ (55,379)	$ (42,425)	$ (83,028)
Net income (loss) attributable to non-controlling interests									169	(57)	57
Net loss attributable to JAKKS Pacific, Inc.	$ (20,293)	$ 16,445	$ (22,542)	$ (29,158)	$ (3,247)	$ 15,682	$ (18,559)	$ (36,244)	(55,548)	(42,368)	(83,085)
Preferred stock dividend									(483)	0	0
Net loss attributable to common stockholders									$ (56,031)	$ (42,368)	$ (83,085)
Weighted average common shares outstanding - basic and diluted (in shares)									25,980	23,104	21,341
Loss per share available to common stockholders - basic and diluted (in dollars per share)									$ (2.16)	$ (1.83)	$ (3.89)