XML 86 R41.htm IDEA: XBRL DOCUMENT v2.4.0.8
Assumptions Used to Estimate Fair Value of Employee Stock Purchase Plan (Detail)
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected dividend yield 0.00% 0.00% 0.00%
Expected volatility, minimum 38.00% 43.00% 39.00%
Expected volatility, maximum 54.00% 58.00% 58.00%
Risk-free interest rate, Minimum 0.10% 0.10% 0.10%
Risk-free interest rate, Maximum 2.50% 1.20% 2.70%
Expected forfeiture 10.00% 10.00% 10.00%
Contractual term of up to 10 years 10 years 10 years
Employee stock purchase plan
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected dividend yield 0.00% 0.00% 0.00%
Expected volatility, minimum 34.00% 41.00% 41.00%
Expected volatility, maximum 53.00% 61.00% 50.00%
Risk-free interest rate, Minimum 0.10% 0.10% 0.20%
Risk-free interest rate, Maximum 0.20% 0.60% 1.80%
Expected forfeiture 0.00% 0.00% 0.00%
Contractual term of up to 24 months 24 months 24 months