Schedule of Share-based Compensation Expense (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense	[1]	$ 3,837	$ 5,218	$ 7,061
Stock Options | Direct Cost Of Revenues
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense	[1]	2,815	3,736	5,404
Stock Options | Selling, General and Administrative Expenses
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense	[1]	966	1,482	1,783
Stock Options | Special Charges
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense	[1],[2]	56		(126)
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense	[3]	16,696	14,001	16,469
Restricted Stock | Direct Cost Of Revenues
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense	[3]	7,530	6,532	8,951
Restricted Stock | Selling, General and Administrative Expenses
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense	[3]	9,117	$ 7,469	8,508
Restricted Stock | Special Charges
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total share-based compensation expense	[2],[3]	$ 49		$ (990)

[1] Includes options and cash-settled stock appreciation rights.

[2] Expense acceleration of $0.2 million related to restricted shares and $0.1 million related to options were netted with expense reversal resulting from forfeitures of $1.2 million and $0.2 million, respectively, for the year ended December 31, 2014. There were no forfeitures related to special charges for the year ended December 31, 2016. (See Note 4, “Special Charges” for information related to the special charges).

[3] Includes restricted share awards, performance and market condition restricted stock units, and cash-settled restricted stock units.