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Commitments and Contingencies (Details) - USD ($)
$ in Millions
 1 Months Ended 3 Months Ended 6 Months Ended
Oct. 18, 2022
Dec. 13, 2019
Mar. 31, 2016
Jun. 30, 2015
Dec. 31, 2019
Jun. 30, 2024
Alaskan Way Viaduct Matter            
Contingencies and Commitments            
Value of claim filed     $ 57.2 $ 532.0    
Settlement on judgment, awarded to other party   $ 57.2        
Pre-tax charge, impact from jury verdict         $ 166.8  
Pre-tax accrual, impact from jury verdict         25.7  
Settlement on judgment         $ 57.2  
Loss contingency, damages paid, value $ 34.6          
Alaskan Way Viaduct Matter | Seattle Tunnel Partners            
Contingencies and Commitments            
Ownership percentage in joint venture           45.00%
Seattle Tunnel Partners            
Contingencies and Commitments            
Value of counterclaim filed in excess of           $ 640.0