Employee Benefit Plans (Tables)
3 Months Ended
Mar. 31, 2015
Compensation and Retirement Disclosure [Abstract]  
Summary of Defined Benefit Pension Plan and Other Postretirement Defined Benefit Plan

 

     Pension Benefits     Other Postretirement Benefits  
     Three Months Ended
March 31,
    Three Months Ended
March 31,
 
     2015     2014     2015     2014  

Service cost

   $ 107      $ 114     $ 7      $ 24   

Interest cost

     2,938        3,335        161        225   

Recognized actuarial loss (gain)

     170        71       (283     (84

Amortization of prior service credits

     —          —          (2,457     (2,494

Expected return on plan assets

     (3,477     (3,814 )     —          —     
  

 

 

   

 

 

   

 

 

   

 

 

 

Net periodic benefit income

$ (262 $ (294 $ (2,572 $ (2,329