Debt - Schedule of Net Interest Expense (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Interest Income Expense Net [Abstract]
Interest expense									$ 14,428	$ 15,240	$ 15,488
Interest income									(2,075)	(1,247)	(217)
Interest expense net of interest income									12,353	13,993	15,271
Capitalized interest									(909)	(788)	(738)
Interest expense, net	$ 2,826	$ 2,763	$ 2,863	$ 2,992	$ 3,350	$ 2,824	$ 3,417	$ 3,614	$ 11,444	$ 13,205	$ 14,533