Quarterly report pursuant to Section 13 or 15(d)

Employee Retirement Plans (Details)

v3.7.0.1
Employee Retirement Plans (Details) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2017
Mar. 31, 2016
Pension plan    
Components of net periodic cost:    
Service cost $ 89 $ 80
Interest cost 403 410
Expected return on plan assets (448) (456)
Amortization of net (gain) loss 181 181
Net periodic pension cost 225 215
Employer contributions during the period 529 193
Pension plan | Minimum    
Components of net periodic cost:    
Estimated total required contributions 216  
Other postretirement benefit cost    
Components of net periodic cost:    
Service cost 51 53
Interest cost 70 70
Amortization of net (gain) loss (27) (32)
Net periodic pension cost $ 94 $ 91