STOCK BASED COMPENSATION - Expense Resulting from Stock Option Awards and ESPP (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 [Line Items]
Stock-based compensation expense	$ 5,254	$ 4,241	$ 16,158	$ 13,365
Stock Options [Member] | Cost of revenues
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	24	14	69	42
Stock Options [Member] | Selling, general and administrative expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	4,416	3,600	13,795	11,459
Restricted Stock Units (RSUs) [Member] | Selling, general and administrative expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	382	319	1,103	948
ESPP shares [Member] | Selling, general and administrative expenses
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 432	$ 308	$ 1,191	$ 916