Goodwill And Identified Intangible Assets - Goodwill (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2017 USD ($)
Goodwill [Roll Forward]
Beginning balance	$ 382,963
Purchase price adjustment related to the acquisition of DTS	2,611
Ending balance	385,574
Product Licensing Segment
Goodwill [Roll Forward]
Ending balance	377,900
Semiconductor and IP Licensing Segment
Goodwill [Roll Forward]
Ending balance	$ 7,700