Summary of Operating Results of Income Tax (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Tax Disclosure [Line Items]
Income (loss) before income taxes	$ 20,172	$ 13,664	$ (10,858)	$ (105,519)
Income tax (benefit) expense	$ (8,302)	$ (68,795)	$ 1,699	$ 17,218
Effective income tax rate	(44.80%)	(503.50%)	(15.60%)	(16.30%)