Acquisitions - Additional Information (Detail) - Rising Tide Games [Member] - USD ($) $ in Millions		3 Months Ended	9 Months Ended
	Sep. 11, 2015	Sep. 30, 2015	Sep. 30, 2015
Business Acquisition [Line Items]
Business acquisition, cost of acquired entity	$ 44.2
Business acquisition, cost of acquired entity, cash paid	22.4
Business acquisition, cost of acquired entity, fair value of contingent consideration	$ 21.8
Business acquisition effective date of acquisition			Sep. 11, 2015
Potential future payments maximum period		3 years	3 years
Potential future payments		$ 140.0	$ 140.0