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Employee Benefit Plans (Details)
$ in Thousands
 3 Months Ended 9 Months Ended
Sep. 30, 2017
USD ($)
plan
Oct. 01, 2016
USD ($)
Sep. 30, 2017
USD ($)
plan
Oct. 01, 2016
USD ($)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]        
Amount Company expects to contribute to its pension plans $ 4,600   $ 4,600  
Payment for pension benefits     $ 2,600 $ 2,900
Multiemployer Plans [Abstract]        
Number Of Multiemployer Plans, Withdrawal Obligation Could Be Material | plan 2   2  
Number Of Multiemployer Plans Withdrawal Obligation Could Be Material Certified Red Zone | plan 1   1  
Number of Multiemployer Plans, Certified Red Zone | plan 6   6  
Number of Multiemployer Plans, Certified Yellow Zone | plan 1   1  
Number Of Multiemployer Plans, Withdrawal Obligation | plan 2   2  
Accrued liability representing the present value of scheduled withdrawal liability payments for under-funded multi-employer plan $ 1,800   $ 1,800  
Maximum [Member]        
Multiemployer Plans [Abstract]        
Multiemployer Plan, Contributions To Individual Plan, Percent     5.00%  
Pension Plan, Defined Benefit [Member]        
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]        
Service cost 759 $ 599 $ 2,244 1,921
Interest cost 1,672 1,702 5,020 5,217
Expected return on plan assets (1,799) (1,886) (5,377) (5,661)
Amortization of prior service cost 9 8 27 22
Amortization of net loss 1,204 1,168 3,610 3,502
Curtailment gain 0 (62) 0 (1,285)
Settlement gain 0 0 0 (123)
Net pension cost $ 1,845 $ 1,529 $ 5,524 $ 3,593