Schedule of Share-based Compensation Expense (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense		$ 4,571	$ 3,806	$ 15,880	$ 19,203
Direct Cost Of Revenues
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense		2,263	2,654	8,396	12,024
Selling, General And Administrative Expenses
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense		$ 2,308	2,146	$ 7,484	8,173
Special Charges
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense	[1]		$ (994)		$ (994)

[1] Special charges of $0.2 million equity award expense acceleration are net of forfeitures of $1.2 million for the three and nine months ended September 30, 2014.