Stock Based Compensation Expense Included in Consolidated Statements of Operations (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation before tax	$ 5,268	$ 3,000	$ 13,721	$ 9,713
Income tax benefit	(1,395)	(893)	(3,977)	(2,941)
Cost of Services
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation before tax	1,418	947	3,816	3,134
Operating Expenses
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation before tax	$ 3,850	$ 2,053	$ 9,905	$ 6,579