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Related Party Transactions (Details)
$ in Millions
12 Months Ended
Dec. 31, 2022
USD ($)
project
Dec. 31, 2021
USD ($)
Dec. 31, 2020
USD ($)
Nov. 04, 2022
USD ($)
Related Party Transactions        
Expenses incurred with related party $ 4.6 $ 4.6 $ 3.2  
Acquisition of property, market value       $ 4.1
Number of mass-transit projects | project 2      
Chairman and Chief Executive Officer        
Related Party Transactions        
Related party, payment for leases $ 3.8 3.6 3.2  
O&G        
Related Party Transactions        
Ownership percentage in joint venture 75.00%      
Related party ownership percentage in joint venture 25.00%      
O&G | Project in Los Angeles, California        
Related Party Transactions        
Number of construction projects | project 2      
Alliant        
Related Party Transactions        
Insurance expense $ 11.4 16.4 $ 16.0  
Owed to related party $ 1.6 $ 1.5