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Property and Equipment - Summary of property and equipment (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Property, Plant and Equipment [Line Items]    
Total property and equipment, gross $ 458,209 $ 415,387
Less: accumulated depreciation and amortization (272,865) (253,495)
Total property and equipment, net 185,344 161,892
Land [Member]    
Property, Plant and Equipment [Line Items]    
Total property and equipment, gross $ 9,301 8,475
Estimated Useful Life in Years 0 years  
Buildings and improvements [Member]    
Property, Plant and Equipment [Line Items]    
Total property and equipment, gross $ 29,747 23,228
Buildings and improvements [Member] | Maximum [Member]    
Property, Plant and Equipment [Line Items]    
Estimated Useful Life in Years 39 years  
Buildings and improvements [Member] | Minimum [Member]    
Property, Plant and Equipment [Line Items]    
Estimated Useful Life in Years 3 years  
Construction equipment [Member]    
Property, Plant and Equipment [Line Items]    
Total property and equipment, gross $ 403,217 371,941
Construction equipment [Member] | Maximum [Member]    
Property, Plant and Equipment [Line Items]    
Estimated Useful Life in Years 12 years  
Construction equipment [Member] | Minimum [Member]    
Property, Plant and Equipment [Line Items]    
Estimated Useful Life in Years 3 years  
Office equipment [Member]    
Property, Plant and Equipment [Line Items]    
Total property and equipment, gross $ 15,944 $ 11,743
Office equipment [Member] | Maximum [Member]    
Property, Plant and Equipment [Line Items]    
Estimated Useful Life in Years 10 years  
Office equipment [Member] | Minimum [Member]    
Property, Plant and Equipment [Line Items]    
Estimated Useful Life in Years 3 years