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Commitments and Contingencies - Narrative (Details)
$ in Thousands
 12 Months Ended
Dec. 31, 2020
USD ($)
employee
collective_bargaining_agreement
Dec. 31, 2019
USD ($)
Dec. 31, 2018
USD ($)
Loss Contingencies [Line Items]      
Number of collective bargaining agreements that are national or regional in scope | collective_bargaining_agreement 2    
Restructuring expenses $ 2,214 $ 1,523 $ 2,306
Restructuring reserve $ 2,697 1,558 1,630
Minimum      
Loss Contingencies [Line Items]      
Number of employees | employee 33,000    
Number of collective bargaining agreements between our individual subsidiaries and local unions | collective_bargaining_agreement 400    
Surety Bond [Member]      
Loss Contingencies [Line Items]      
Aggregate estimated exposure, certain performance obligations $ 1,300,000    
Aggregate estimated exposure, certain performance obligations, percentage 29.00%    
Aggregate estimated exposure, other contractual obligations $ 37,500    
Employee Severance [Member]      
Loss Contingencies [Line Items]      
Restructuring expenses $ 2,200 $ 1,500 $ 2,300
Unionized Employees Concentration Risk [Member] | Workforce Subject to Collective Bargaining Arrangements [Member]      
Loss Contingencies [Line Items]      
Percentage of employees represented by unions 59.00%