Segment Information - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) segment	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Segment Reporting Information [Line Items]
Number of operating business segments | segment	4
Revenues	$ 407,144	$ 389,507	$ 373,528
Major Customer | Sales Revenue, Net
Segment Reporting Information [Line Items]
Revenues	$ 175,400	$ 174,400	$ 167,300
Major Customer | Sales Revenue, Net | Customer Concentration Risk
Segment Reporting Information [Line Items]
Percentage of total revenue from major customer	43.00%	45.00%	45.00%
Puerto Rico | Sales Revenue, Net | Customer Concentration Risk
Segment Reporting Information [Line Items]
Percentage of total revenue from major customer	7.00%	7.00%	9.00%