v3.25.2
FAIR VALUE MEASUREMENTS - Significant Unobservable Inputs (Details) - USD ($)
Jun. 30, 2025
Dec. 31, 2024
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair value, assets $ 728,200,000 $ 499,500,000
Fair value, liabilities 297,700,000 324,400,000
APCo    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair value, assets 109,900,000 37,100,000
Fair value, liabilities 2,300,000 2,200,000
I&M    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair value, assets 12,300,000 18,400,000
Fair value, liabilities 1,200,000 700,000
OPCo    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair value, assets 0 0
Fair value, liabilities 47,700,000 47,500,000
PSO    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair value, assets 96,900,000 22,000,000.0
Fair value, liabilities 8,100,000 5,800,000
SWEPCo    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair value, assets 70,400,000 18,100,000
Fair value, liabilities 3,800,000 2,300,000
Level 3    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair value, assets 517,100,000 313,500,000
Fair value, liabilities 134,300,000 147,900,000
Energy Contracts | Level 3    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair value, assets 204,200,000 221,200,000
Fair value, liabilities 129,700,000 144,600,000
Energy Contracts | Level 3 | OPCo    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair value, assets 0 0
Fair value, liabilities $ 47,700,000 $ 47,500,000
Energy Contracts | Level 3 | Low | Forward Market Price    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Input/Range, asset 4.80 2.75
Input/Range, liability 4.80 2.75
Energy Contracts | Level 3 | Low | OPCo | Forward Market Price    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Input/Range, asset 12.54 14.53
Input/Range, liability 12.54 14.53
Energy Contracts | Level 3 | High | Forward Market Price    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Input/Range, asset 129.40 149.30
Input/Range, liability 129.40 149.30
Energy Contracts | Level 3 | High | OPCo | Forward Market Price    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Input/Range, asset 75.71 72.40
Input/Range, liability 75.71 72.40
Energy Contracts | Level 3 | Weighted Average | Forward Market Price    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Input/Range, asset 47.56 49.34
Input/Range, liability 47.56 49.34
Energy Contracts | Level 3 | Weighted Average | OPCo | Forward Market Price    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Input/Range, asset 41.08 42.44
Input/Range, liability 41.08 42.44
FTRs | Level 3    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair value, assets $ 312,900,000 $ 92,300,000
Fair value, liabilities 4,600,000 3,300,000
FTRs | Level 3 | APCo    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair value, assets 108,600,000 35,200,000
Fair value, liabilities 300,000 0
FTRs | Level 3 | I&M    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair value, assets 13,000,000.0 6,900,000
Fair value, liabilities 700,000 500,000
FTRs | Level 3 | PSO    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair value, assets 97,000,000.0 20,800,000
Fair value, liabilities 100,000 800,000
FTRs | Level 3 | SWEPCo    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair value, assets 70,700,000 18,100,000
Fair value, liabilities $ 1,600,000 $ 600,000
FTRs | Level 3 | Low | Forward Market Price    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Input/Range, asset (32.49) (29.48)
Input/Range, liability (32.49) (29.48)
FTRs | Level 3 | Low | APCo | Forward Market Price    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Input/Range, asset (1.40) (0.25)
Input/Range, liability (1.40) (0.25)
FTRs | Level 3 | Low | I&M | Forward Market Price    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Input/Range, asset (0.90) (4.07)
Input/Range, liability (0.90) (4.07)
FTRs | Level 3 | Low | PSO | Forward Market Price    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Input/Range, asset (32.49) (29.48)
Input/Range, liability (32.49) (29.48)
FTRs | Level 3 | Low | SWEPCo | Forward Market Price    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Input/Range, asset (32.49) (29.48)
Input/Range, liability (32.49) (29.48)
FTRs | Level 3 | High | Forward Market Price    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Input/Range, asset 28.81 19.70
Input/Range, liability 28.81 19.70
FTRs | Level 3 | High | APCo | Forward Market Price    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Input/Range, asset 14.50 9.32
Input/Range, liability 14.50 9.32
FTRs | Level 3 | High | I&M | Forward Market Price    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Input/Range, asset 14.50 9.32
Input/Range, liability 14.50 9.32
FTRs | Level 3 | High | PSO | Forward Market Price    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Input/Range, asset 5.35 10.54
Input/Range, liability 5.35 10.54
FTRs | Level 3 | High | SWEPCo | Forward Market Price    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Input/Range, asset 5.35 10.54
Input/Range, liability 5.35 10.54
FTRs | Level 3 | Weighted Average | Forward Market Price    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Input/Range, asset (0.20) 0.24
Input/Range, liability (0.20) 0.24
FTRs | Level 3 | Weighted Average | APCo | Forward Market Price    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Input/Range, asset 2.10 1.56
Input/Range, liability 2.10 1.56
FTRs | Level 3 | Weighted Average | I&M | Forward Market Price    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Input/Range, asset 1.05 1.34
Input/Range, liability 1.05 1.34
FTRs | Level 3 | Weighted Average | PSO | Forward Market Price    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Input/Range, asset (5.18) (3.88)
Input/Range, liability (5.18) (3.88)
FTRs | Level 3 | Weighted Average | SWEPCo | Forward Market Price    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Input/Range, asset (5.18) (3.88)
Input/Range, liability (5.18) (3.88)