Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Tax Disclosure [Abstract]
Income tax (benefit) expense	$ (140)	$ 4,500	$ (15,352)	$ 100
(Loss) income before income taxes	$ (237)	$ 9,600	$ (66,889)	$ (183,400)
Effective income tax percent	59.20%	46.80%	23.00%	(0.10%)
United States federal statutory income tax rate, percent			21.00%