Annual report pursuant to Section 13 and 15(d)

Employee Retirement Plans - Reconciliations (Details)

v3.8.0.1
Employee Retirement Plans - Reconciliations (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Components of net periodic cost:      
Service cost $ 561 $ 531  
Net periodic pension cost 1,278 1,221  
Change in plan assets:      
Fair value of plan assets at beginning of year 29,223    
Fair value of plan assets at end of year 33,903 29,223  
Amounts recognized in the consolidated balance sheets consisted      
Retiree health benefit obligation 6,809 7,193  
Pension plan      
Components of net periodic cost:      
Service cost 356 321 $ 257
Interest cost 1,613 1,639 1,489
Expected return on plan assets (1,790) (1,824) (1,630)
Amortization of net (gain) loss 723 724 1,021
Net periodic pension cost 902 860 1,137
Employer contributions during the period 1,669 1,711  
Change in projected benefit obligation:      
Benefit obligation at beginning of year 39,407 37,217  
Actuarial (gain) loss 3,571 1,469  
Benefits paid (1,283) (1,239)  
Benefit obligation at end of year 43,664 39,407 37,217
Change in plan assets:      
Fair value of plan assets at beginning of year 29,223 26,378  
Actual return (loss) on plan assets 4,294 2,373  
Benefits paid (1,283) (1,239)  
Fair value of plan assets at end of year 33,903 29,223 26,378
Defined Benefit Plan, Funded Status of Plan, Total (9,761) (10,184)  
Salaried Pension Plan      
Accumulated benefit obligation 42,876 38,799  
Pension plan | Minimum      
Components of net periodic cost:      
Employer contributions during the period 169    
Other postretirement benefit cost      
Components of net periodic cost:      
Service cost 205 210 229
Interest cost 278 278 256
Amortization of net (gain) loss (107) (127) (69)
Net periodic pension cost 376 361 416
Change in projected benefit obligation:      
Benefit obligation at beginning of year 7,333 6,896  
Participant contributions 25 38  
Actuarial (gain) loss (853) 53  
Benefits paid (39) (142)  
Benefit obligation at end of year 6,949 7,333 $ 6,896
Change in plan assets:      
Benefits paid $ (39) (142)  
Period of coverage under the plan 10 years    
Amounts recognized in the consolidated balance sheets consisted      
Accrued expenses and other current liabilities $ 140 140  
Retiree health benefit obligation 6,809 7,193  
Amounts recognized in the consolidated balance sheets $ 6,949 $ 7,333  
Salaried Pension Plan      
Period of service of employees 12 years