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Property and Equipment - Summary of Property and Equipment (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Property, Plant and Equipment [Line Items]    
Total property and equipment, gross $ 479,480 $ 458,209
Less: accumulated depreciation and amortization (294,366) (272,865)
Property and equipment, net 185,114 185,344
Land    
Property, Plant and Equipment [Line Items]    
Total property and equipment, gross 9,301 9,301
Buildings and improvements    
Property, Plant and Equipment [Line Items]    
Total property and equipment, gross 33,452 29,747
Construction equipment    
Property, Plant and Equipment [Line Items]    
Construction equipment 420,002 403,217
Office equipment    
Property, Plant and Equipment [Line Items]    
Total property and equipment, gross $ 16,725 $ 15,944
Minimum | Buildings and improvements    
Property, Plant and Equipment [Line Items]    
Estimated Useful Life in Years 3 years  
Minimum | Construction equipment    
Property, Plant and Equipment [Line Items]    
Estimated Useful Life in Years 3 years  
Minimum | Office equipment    
Property, Plant and Equipment [Line Items]    
Estimated Useful Life in Years 3 years  
Maximum | Buildings and improvements    
Property, Plant and Equipment [Line Items]    
Estimated Useful Life in Years 39 years  
Maximum | Construction equipment    
Property, Plant and Equipment [Line Items]    
Estimated Useful Life in Years 12 years  
Maximum | Office equipment    
Property, Plant and Equipment [Line Items]    
Estimated Useful Life in Years 10 years