Stock-Based Compensation Expense Resulting from Stock Option Awards and ESPP (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 4,085	$ 3,863
Stock Options | Cost of revenues
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	38	26
Stock Options | Selling, general and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	3,480	3,424
Restricted stock units | Selling, general and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	303	158
Employee Stock Purchase Plan (ESPP) | Selling, general and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 264	$ 255