Summary of Benefit from Income Taxes and Discrete Tax Items (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Tax Rate Reconciliation [Line Items]
(Benefit) from income taxes	[1]	$ (10,881)	$ (14,123)	$ (15,103)	$ (508)
Effective income tax rate				113.00%	(1.00%)

[1] On January 1, 2018 the Company adopted the ASC 606 revenue recognition standard and has adjusted prior periods to conform. See Note 2. "New Accounting Pronouncements" for additional information.