XML 58 R43.htm IDEA: XBRL DOCUMENT v3.8.0.1
Stock-Based Compensation - Plan details (Details)
12 Months Ended
Jan. 01, 2016
shares
Jan. 01, 2014
shares
Dec. 31, 2017
item
$ / shares
shares
Dec. 31, 2016
$ / shares
shares
Dec. 31, 2015
$ / shares
shares
Stock options          
Stock-based compensation          
Total number of shares of common stock available for issuance     3,394,651 2,943,216 2,917,182
Options granted (in shares)     1,511,100 1,429,500  
Information with respect to stock options outstanding          
Exercisable options (in shares)     2,558,941 1,743,765 1,600,351
Weighted-average exercise price per share of exercisable options (in dollars per share) | $ / shares     $ 11.06 $ 8.87 $ 3.99
Weighted average grant date fair value per share of options granted during the year (in dollars per share) | $ / shares     $ 16.92 $ 10.30 $ 10.66
Weighted-average remaining contractual life     6 years 6 months 29 days 7 years 9 months 26 days 6 years 11 months 23 days
Employee Stock Purchase Plan          
Stock-based compensation          
Total number of shares of common stock available for issuance     581,286    
Initial term of plan     2 years    
Second term of plan     2 years    
Number of six month purchase periods | item     4    
Purchase period     6 months    
Increase in shares of common stock available for issuance (in shares)   313,545 0 0 0
Awards issued under the plan (in shares)     292,393 221,486  
Employee Stock Purchase Plan | Minimum          
Stock-based compensation          
Percentage of compensation that employees may withhold to purchase stock at a discount     1.00%    
Employee Stock Purchase Plan | Maximum          
Stock-based compensation          
Percentage of compensation that employees may withhold to purchase stock at a discount     15.00%    
Purchase price as percentage of stock price at the initial offering date     85.00%    
Purchase price as percentage of stock price at the purchase date     85.00%    
Annual percentage increase in shares of common stock available for issuance     1.00%    
Annual increase in shares of common stock available for issuance (in shares)     621,814    
The 2010 Plan          
Stock-based compensation          
Total number of shares of common stock available for issuance     0    
The 2013 Plan          
Stock-based compensation          
Total number of shares of common stock available for issuance     8,526,465    
Annual percentage increase in shares of common stock available for issuance     4.00%    
Increase in shares of common stock available for issuance (in shares) 1,862,719        
Awards issued under the plan (in shares)     4,945,350