Stock-Based Compensation Expense Included in Consolidated Statements of Operations (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation before tax	$ 13,932	$ 10,881	$ 26,440	$ 19,816
Income tax benefit	(4,287)	(3,085)	(8,102)	(5,690)
Cost of revenue
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation before tax	3,677	2,914	7,299	5,594
Operating expenses
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation before tax	$ 10,255	$ 7,967	$ 19,141	$ 14,222