Segment Reporting - Additional Information (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($) Segment	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | Segment	3
Revenues	$ 140,654	$ 123,527
Assets	2,072,770		$ 2,073,407
United States
Segment Reporting Information [Line Items]
Revenues	117,700	$ 102,600
Assets	$ 1,500,000		$ 1,500,000