Joint Ventures - Additional Information (Detail) shares in Millions	1 Months Ended	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2012 USD ($) shares	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($) project	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Apr. 27, 2017	Oct. 31, 2016	Dec. 31, 2012 USD ($)
Schedule of Equity Method Investments [Line Items]
Write-off of investment in DreamPlay, LLC				$ 0	$ 7,000,000	$ 0
Net income (loss) attributable to non-controlling interests				$ (57,000)	57,000	6,000
Pacific Animation Partners Joint Venture
Schedule of Equity Method Investments [Line Items]
Percentage of ownership interest in joint venture				50.00%
Number of episodes for which production completed | project				65
Equity in net income/(loss) of joint venture				$ 22,000	16,000	700,000
Joint venture balance				$ 0	0	0
DreamPlay Toys
Schedule of Equity Method Investments [Line Items]
Percentage of ownership interest in joint venture	50.00%
Cash paid to acquire interest in joint venture	$ 8,000,000
DreamPlay, LLC
Schedule of Equity Method Investments [Line Items]
Percentage of ownership interest in joint venture									5.00%
Cash paid to acquire interest in joint venture	$ 7,000,000
Write-off of investment in DreamPlay, LLC			$ 7,000,000
China Joint Venture
Schedule of Equity Method Investments [Line Items]
Percentage of ownership interest in joint venture				51.00%
Net income (loss) attributable to non-controlling interests				$ (57,000)	57,000	$ 6,000
Hong Kong Meisheng Cultural Co
Schedule of Equity Method Investments [Line Items]
Percentage of ownership interest in joint venture								50.00%
Net income (loss) attributable to non-controlling interests				$ 0	$ 0
Technology Rights | DreamPlay Toys
Schedule of Equity Method Investments [Line Items]
Write-off of investment in DreamPlay, LLC		$ 2,900,000
Minimum | Hong Kong Meisheng Cultural Co
Schedule of Equity Method Investments [Line Items]
Ownership percentage							10.00%
NantWorks | DreamPlay Toys
Schedule of Equity Method Investments [Line Items]
Issue of warrants (in shares) | shares	1.5
Value of warrants issued									$ 7,000,000