Goodwill - Additional Information (Detail) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Jan. 31, 2016	Dec. 31, 2016
Sproutling Inc.
Business Acquisition [Line Items]
Consideration paid for business acquisition	$ 9.9
Duration of contingent consideration agreement	3 years
Fuhu Inc.
Business Acquisition [Line Items]
Consideration paid for business acquisition	$ 23.3
Fuhu Inc. and Sproutling Inc.
Business Acquisition [Line Items]
Integration costs recognized		$ 2.0