Schedule of Carrying Amount of Goodwill (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2016 USD ($)
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill, Beginning Balance	$ 396,220
Goodwill, Acquisition	40,789
Goodwill, Ending Balance	437,009
Net Book Value, Beginning Balance	396,220
Net Book Value, Acquisition	40,789
Net Book Value, Ending Balance	$ 437,009