Acquisitions - Additional Information (Detail) - USD ($) $ in Thousands		9 Months Ended
	Feb. 14, 2017	Sep. 30, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Intangible assets		$ 40,517	$ 25,430
Noncompetition Agreements [Member]
Business Acquisition [Line Items]
Intangible assets		$ 5,235
Harpan LLC [Member]
Business Acquisition [Line Items]
Business acquisition effective date of acquisition		Feb. 14, 2017
Business acquisition, cost of acquired entity, cash paid	$ 42,500
Estimated amount allocated to business combination	35,081
Harpan LLC [Member] | Noncompetition Agreements [Member]
Business Acquisition [Line Items]
Intangible assets	$ 7,400
Intangible assets, useful life		2 years