XML 52 R40.htm IDEA: XBRL DOCUMENT v3.7.0.1
Preferred Stock and Stockholders' Equity - Fair Value of Option Awards amd ESPP Purchase Rights Granted (Details) - $ / shares
3 Months Ended
Apr. 01, 2017
Apr. 02, 2016
Minimum    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected dividend rate (percent) 0.00% 0.00%
Minimum | ESPP Purchase Right    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected term (in years) 6 months 6 months
Risk-free interest rate 0.67% 0.42%
Expected volatility (percent) 58.30% 55.80%
Grant date fair value per share $ 11.94 $ 7.75
Maximum | ESPP Purchase Right    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected term (in years) 2 years 2 years
Risk-free interest rate 1.00% 0.74%
Expected volatility (percent) 68.60% 67.20%
Grant date fair value per share $ 16.42 $ 12.26