Goodwill and Intangible Assets - Components of Goodwill (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Goodwill And Intangible Assets Disclosure [Abstract]
Beginning balance	$ 112,425	$ 39,870
Additions through acquisitions	1,409	72,528
Measurement period adjustments	199	27
Ending balance	$ 114,033	$ 112,425