STOCK BASED COMPENSATION - Stock-Based Compensation Expense Resulting from Stock Option Awards, RSUs, PSUs and ESPP (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 5,382	$ 5,114	$ 17,262	$ 16,671
Stock Options | Cost of revenues
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	13	26	39	53
Stock Options | Selling, general and administrative expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	3,650	4,287	11,539	13,624
Restricted Stock Units (RSUs) | Selling, general and administrative expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	1,189	302	4,136	1,260
Performance-Based Restricted Stock Units | Selling, general and administrative expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	201	0	577	0
ESPP | Selling, general and administrative expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 329	$ 499	$ 971	$ 1,734