XML 46 R34.htm IDEA: XBRL DOCUMENT v3.23.3
Intangible Assets - Gross and Net Intangible Assets (Details) - USD ($)
$ in Millions
Sep. 30, 2023
Dec. 31, 2022
Finite-Lived Intangible Assets [Line Items]    
Gross Carrying Amount $ 40.0 $ 40.0
Accumulated Amortization 11.8 10.2
Net $ 28.2 29.8
Customer relationships    
Finite-Lived Intangible Assets [Line Items]    
Weighted - Average Remaining Amortization Years 1 year  
Gross Carrying Amount $ 6.7 6.7
Accumulated Amortization 6.0 5.6
Net $ 0.7 1.1
Permits    
Finite-Lived Intangible Assets [Line Items]    
Weighted - Average Remaining Amortization Years 19 years  
Gross Carrying Amount $ 31.7 31.7
Accumulated Amortization 5.6 4.5
Net $ 26.1 27.2
Other    
Finite-Lived Intangible Assets [Line Items]    
Weighted - Average Remaining Amortization Years 27 years  
Gross Carrying Amount $ 1.6 1.6
Accumulated Amortization 0.2 0.1
Net $ 1.4 $ 1.5