Quarterly report pursuant to Section 13 or 15(d)

Employee Retirement Plans (Details)

v3.10.0.1
Employee Retirement Plans (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Sep. 14, 2018
Sep. 30, 2018
Sep. 30, 2017
Sep. 30, 2018
Sep. 30, 2017
Components of net periodic cost:          
Discretionary contribution received $ 7,000        
Pension plan          
Components of net periodic cost:          
Service cost   $ 102 $ 89 $ 306 $ 267
Interest cost   389 403 1,167 1,209
Expected return on plan assets   (475) (448) (1,425) (1,344)
Amortization of net (gain) loss   176 181 528 543
Net periodic pension cost   192 225 576 675
Employer contributions during the period       7,047 655
Pension plan | Minimum          
Components of net periodic cost:          
Estimated total required contributions   72   72  
Other postretirement benefit cost          
Components of net periodic cost:          
Service cost   47 51 141 153
Interest cost   58 70 174 210
Amortization of net (gain) loss   (52) (27) (156) (81)
Net periodic pension cost   $ 53 $ 94 $ 159 $ 282