Basis of Presentation and Significant Accounting Policies (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Contract receivables	$ 73,400,000	$ 79,400,000
Allowance for doubtful accounts against contracts receivable	$ 0	0
Ownership interest in subsidiaries	50.00%
Other current assets
Property, Plant and Equipment [Line Items]
Restricted cash, current	$ 4,700,000	$ 4,800,000
Heavy Civil | Minimum
Property, Plant and Equipment [Line Items]
Percentage of completion range	12 months
Heavy Civil | Maximum
Property, Plant and Equipment [Line Items]
Percentage of completion range	36 months
Specialty Services | Minimum
Property, Plant and Equipment [Line Items]
Percentage of completion range	6 months
Specialty Services | Maximum
Property, Plant and Equipment [Line Items]
Percentage of completion range	24 months
Building and Building Improvements | Minimum
Property, Plant and Equipment [Line Items]
Property and equipment useful life	5 years
Building and Building Improvements | Maximum
Property, Plant and Equipment [Line Items]
Property and equipment useful life	39 years
Equipment | Minimum
Property, Plant and Equipment [Line Items]
Property and equipment useful life	5 years
Equipment | Maximum
Property, Plant and Equipment [Line Items]
Property and equipment useful life	20 years