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Asset Retirement Obligations (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Changes to asset retirement obligations      
Balance as of January 1 $ 513.5 $ 483.5 $ 461.4
Accretion 21.2 20.7 22.1
Additions and revisions to estimated cash flows (53.9) 39.7 39.1
Liabilities settled (18.8) (30.4) (39.1)
Balance as of December 31 462.0 513.5 483.5
Wind generation projects      
Changes to asset retirement obligations      
ARO additions     10.7
PGL and NSG | Natural gas distribution pipe      
Changes to asset retirement obligations      
ARO increase (decrease) due to revisions made to estimated cash flows (152.0)    
PGL and NSG | Natural gas distribution lines      
Changes to asset retirement obligations      
ARO additions 50.7    
WPS, Tatanka, and Jayhawk | Wind generation projects      
Changes to asset retirement obligations      
ARO additions 26.3    
WE and WPS | Wind generation projects      
Changes to asset retirement obligations      
ARO increase (decrease) due to revisions made to estimated cash flows 7.8    
WPS | Fly ash landfills and ash ponds      
Changes to asset retirement obligations      
ARO increase (decrease) due to revisions made to estimated cash flows $ 6.8    
WPS | Two Creeks      
Changes to asset retirement obligations      
ARO additions   8.5  
PGL | Natural gas distribution lines      
Changes to asset retirement obligations      
ARO additions   39.3 40.1
WE | Abatement of asbestos      
Changes to asset retirement obligations      
ARO increase (decrease) due to revisions made to estimated cash flows   $ (9.2) $ (7.3)