Goodwill and Intangible Assets - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
Amortization expense	$ 2,400	$ 2,100	$ 4,900	$ 4,685
Estimated amortization expense, remainder of 2018	4,700		4,700
Estimated amortization expense, year 2019	9,600		9,600
Estimated amortization expense, year 2020	9,600		9,600
Estimated amortization expense, year 2021	9,600		9,600
Estimated amortization expense, year 2022	9,600		9,600
Estimated amortization expense, thereafter	$ 54,600		$ 54,600