Annual report pursuant to Section 13 and 15(d)

Stock Option and Purchase Plans - Summary of Weighted-Average Assumptions (Detail)

v3.3.1.900
Stock Option and Purchase Plans - Summary of Weighted-Average Assumptions (Detail)
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award      
Dividend yield 0.00% 0.00% 0.00%
Minimum      
Share-based Compensation Arrangement by Share-based Payment Award      
Risk-free interest rate 1.36% 0.12% 0.88%
Volatility factor 0.40% 0.42% 0.51%
Expected life in years 4 years 4 years 5 years
Maximum      
Share-based Compensation Arrangement by Share-based Payment Award      
Risk-free interest rate 2.10% 2.30% 2.22%
Volatility factor 0.51% 0.52% 0.56%
Expected life in years 8 years 8 years 8 years