Annual report pursuant to Section 13 and 15(d)

Benefit Plans - Stock Options Activity Under Share-Based Payment Plans (Details)

v3.8.0.1
Benefit Plans - Stock Options Activity Under Share-Based Payment Plans (Details) - Employees And Non Employee Stock Option - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Options      
Outstanding as of beginning of period (in shares) 332,648 338,481 267,854
Granted (in shares) 27,339 55,222 145,366
Exercised (in shares) (73,296) (50,728) (57,667)
Forfeited, cancelled or expired (in shares) (6,234) (10,327) (17,072)
Outstanding as of end of period (in shares) 280,457 332,648 338,481
Exercisable (in shares) 131,025    
Weighted- Average Exercise Price Per Share      
Outstanding as of beginning of period (in dollars per share) $ 3.50 $ 3.29 $ 2.72
Granted (in dollars per share) 5.49 4.14 3.95
Exercised (in dollars per share) 3.21 2.66 1.88
Forfeited, cancelled or expired (in dollars per share) 4.07 4.30 4.60
Outstanding as of end of period (in dollars per share) 3.76 $ 3.50 $ 3.29
Exercisable (in dollars per share) $ 3.23    
Weighted- Average Remaining Contractual Term (Years)      
Outstanding 6 years 7 months 24 days    
Exercisable 5 years 5 months 20 days    
Aggregate Intrinsic Value      
Outstanding $ 453,955    
Exercisable $ 279,101