v3.4.0.3
Stock-Based Compensation (Tables)
3 Months Ended
Mar. 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]  
Summary of Share Based Compensation Expense

The table below sets forth the total amount of stock-based compensation expense for the three months and quarters ended March 31, 2016 and 2015.

 

     Quarter Ended
March 31,
 
     2016      2015  

Stock-based compensation expense:

     (Thousands of dollars)   

Time-based restricted stock units

   $ 619       $ 637   

Performance-based restricted stock units

     871         1,082   
  

 

 

    

 

 

 

Total stock-based compensation expense

   $ 1,490       $ 1,719