v3.3.1.900
Fair Value (Tables)
 12 Months Ended
Dec. 31, 2015
Fair Value Disclosures [Abstract]  
Summary of Valuation of Investments and Financial Instruments Pricing Levels

The following tables summarize the valuation of our investments and financial instruments by the above pricing levels as of the valuation dates listed:

 

            December 31, 2015  
     Total      (Level 1)      (Level 2)  

Investments:

         

Money Market Mutual Funds

    $ 18,181       $ 18,181       $ —     

Commercial Paper

      5,981         —           5,981   

U.S. Government Agencies

      11,469         —           11,469   

Corporate bonds and notes

      264,228         —           264,228   
  

 

 

     

 

 

     

 

 

  
     299,859         18,181         281,678   

Deferred compensation plan assets

      2,294         2,294         —     
  

 

 

     

 

 

     

 

 

  

Total

    $ 302,153       $ 20,475       $ 281,678   
  

 

 

     

 

 

     

 

 

  

 

            December 31, 2014  
     Total      (Level 1)      (Level 2)  

Investments:

         

Money Market Mutual Funds

    $ 68,612       $ 68,612       $ —     

Municipal bonds and notes

      1,502         —           1,502   

Corporate bonds and notes

      130,615         —           130,615   
  

 

 

     

 

 

     

 

 

  
     200,729         68,612         132,117   

Deferred compensation plan assets

      2,386         2,386         —     
  

 

 

     

 

 

     

 

 

  

Total

    $ 203,115       $ 70,998       $ 132,117   
  

 

 

     

 

 

     

 

 

  
Summary of Combined Fair Value of Assets that Incurred Impairments

The below table summarizes the combined fair value of the assets that incurred impairments during the years ended December 31, 2015 and 2014, along with the amount of the impairment. The impairment charges were recorded in Impairment of assets.

 

     Year Ended December 31,  
     2015      2014  
     (Thousands of dollars)  

Amount of impairment incurred

    $ —         $ 10,508   

Combined fair value of assets incurring impairment

    $ —         $ 6,000