Restructuring - Schedule of Details of Restructuring Expense (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018
Restructuring Cost and Reserve [Line Items]
Total restructuring	$ 6,376	$ 6,570
Severance And Termination Benefits [Member]
Restructuring Cost and Reserve [Line Items]
Total restructuring	4,032	4,226
Reversal of Stock Based Compensation Expense [Member]
Restructuring Cost and Reserve [Line Items]
Total restructuring	(1,402)	(1,402)
Accelerated Deferred Compensation [Member]
Restructuring Cost and Reserve [Line Items]
Total restructuring	523	523
Intangible Assets Impairment [Member]
Restructuring Cost and Reserve [Line Items]
Total restructuring	2,623	2,623
Write-off of Allocated Goodwill [Member]
Restructuring Cost and Reserve [Line Items]
Total restructuring	$ 600	$ 600