Changes in the Carrying Amount of Goodwill (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($)
Goodwill And Intangible Assets Disclosure [Abstract]
Balance as of December 31, 2015	$ 34,972
Goodwill acquired	2,476
Balance as of December 31, 2016	$ 37,448