Quarterly report pursuant to Section 13 or 15(d)

Employee Retirement Plans (Details)

v3.5.0.2
Employee Retirement Plans (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2016
Jun. 30, 2015
Jun. 30, 2016
Jun. 30, 2015
Pension plan        
Components of net periodic cost:        
Service cost $ 80 $ 64 $ 160 $ 128
Interest cost 410 372 820 744
Expected return on plan assets (456) (407) (912) (814)
Amortization of net (gain) loss 181 255 362 510
Net periodic cost 215 284 430 568
Employer contributions during the period     711 476
Pension plan | Minimum        
Components of net periodic cost:        
Estimated total required contributions 967   967  
Other postretirement benefit cost        
Components of net periodic cost:        
Service cost 52 57 105 114
Interest cost 69 64 139 128
Amortization of net (gain) loss (31) (17) (63) (34)
Net periodic cost $ 90 $ 104 $ 181 $ 208