Contract Assets and Liabilities - Narrative (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021 USD ($) project	Jun. 30, 2020 USD ($) project	Jun. 30, 2021 USD ($) project	Jun. 30, 2020 USD ($) project	Dec. 31, 2020 USD ($)
Property, Plant and Equipment [Line Items]
Percentage completed of certain milestones			10.00%
Net realizable value of unapproved orders	$ 40,100		$ 40,100		$ 33,600
Gross profit write downs	1,100	$ 2,000	1,700	$ 3,400
Revision amount for gross profit impact on contract estimates (more than)	250		250
Number of projects subject to gross profit write ups | project		0
GCR
Property, Plant and Equipment [Line Items]
Gross profit write downs	$ 1,700	$ 1,500	$ 3,500	$ 5,200
Number of projects subject to gross profit write downs | project	3	4	8	8
Gross profit write ups			$ 900	$ 1,200
Number of projects subject to gross profit write ups | project				2
GCR | Michigan Region Project
Property, Plant and Equipment [Line Items]
Gross profit write downs	$ 1,000		$ 1,200
Number of projects subject to gross profit write downs | project	1		2
Gross profit write ups			$ 500
Number of projects subject to gross profit write ups | project			1
GCR | New England Region Project
Property, Plant and Equipment [Line Items]
Gross profit write downs	$ 300		$ 300
Number of projects subject to gross profit write downs | project	1		1
GCR | Southern California Region Project
Property, Plant and Equipment [Line Items]
Gross profit write downs	$ 400	$ 700	$ 800
Number of projects subject to gross profit write downs | project	1	2	2
GCR | Eastern Pennsylvania Region Project
Property, Plant and Equipment [Line Items]
Gross profit write downs			$ 1,000
Number of projects subject to gross profit write downs | project			2
GCR | Florida Region Project
Property, Plant and Equipment [Line Items]
Gross profit write ups	$ 300
Number of projects subject to gross profit write ups | project	1
GCR | Mid-Atlantic Region Project
Property, Plant and Equipment [Line Items]
Gross profit write downs			$ 300
Number of projects subject to gross profit write downs | project			1
GCR | Ohio Region Project
Property, Plant and Equipment [Line Items]
Gross profit write ups			$ 400
Number of projects subject to gross profit write ups | project			1
ODR
Property, Plant and Equipment [Line Items]
Gross profit write downs	$ 300		$ 300
Number of projects subject to gross profit write downs | project	1		1
ODR | Michigan Region Project
Property, Plant and Equipment [Line Items]
Gross profit write ups	$ 300
Number of projects subject to gross profit write ups | project	1
ODR | Eastern Pennsylvania Region Project
Property, Plant and Equipment [Line Items]
Gross profit write downs	$ 300		$ 300
Number of projects subject to gross profit write downs | project	1		1