Construction Contract and Other Service Revenues - Construction Contracts and Other Service Revenues by Compensation Arrangement and Service Type (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Construction contract and other service revenues	$ 16,558	$ 13,681
Construction
Disaggregation of Revenue [Line Items]
Construction contract and other service revenues	15,756	12,883
Design
Disaggregation of Revenue [Line Items]
Construction contract and other service revenues	302	542
Other
Disaggregation of Revenue [Line Items]
Construction contract and other service revenues	500	256
Cost-plus fee
Disaggregation of Revenue [Line Items]
Construction contract and other service revenues	12,486	3,309
Guaranteed maximum price
Disaggregation of Revenue [Line Items]
Construction contract and other service revenues	2,101	5,044
Firm fixed price
Disaggregation of Revenue [Line Items]
Construction contract and other service revenues	1,471	5,072
Other
Disaggregation of Revenue [Line Items]
Construction contract and other service revenues	$ 500	$ 256