v3.26.3
REVENUE FROM CONTRACTS WITH CUSTOMERS - Performance Obligation (Details)
$ in Millions
Sep. 30, 2026
USD ($)
Disaggregation of Revenue [Line Items]  
Fixed performance obligations $ 86
APCo  
Disaggregation of Revenue [Line Items]  
Fixed performance obligations 24
I&M  
Disaggregation of Revenue [Line Items]  
Fixed performance obligations 3
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-10-01  
Disaggregation of Revenue [Line Items]  
Fixed performance obligations $ 18
Revenue, remaining performance obligation, expected timing of satisfaction, period 3 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-10-01 | APCo  
Disaggregation of Revenue [Line Items]  
Fixed performance obligations $ 2
Revenue, remaining performance obligation, expected timing of satisfaction, period 3 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-10-01 | I&M  
Disaggregation of Revenue [Line Items]  
Fixed performance obligations $ 0
Revenue, remaining performance obligation, expected timing of satisfaction, period 3 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2027-01-01  
Disaggregation of Revenue [Line Items]  
Fixed performance obligations $ 54
Revenue, remaining performance obligation, expected timing of satisfaction, period 2 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2027-01-01 | APCo  
Disaggregation of Revenue [Line Items]  
Fixed performance obligations $ 13
Revenue, remaining performance obligation, expected timing of satisfaction, period 2 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2027-01-01 | I&M  
Disaggregation of Revenue [Line Items]  
Fixed performance obligations $ 1
Revenue, remaining performance obligation, expected timing of satisfaction, period 2 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2029-01-01  
Disaggregation of Revenue [Line Items]  
Fixed performance obligations $ 12
Revenue, remaining performance obligation, expected timing of satisfaction, period 2 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2029-01-01 | APCo  
Disaggregation of Revenue [Line Items]  
Fixed performance obligations $ 7
Revenue, remaining performance obligation, expected timing of satisfaction, period 2 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2029-01-01 | I&M  
Disaggregation of Revenue [Line Items]  
Fixed performance obligations $ 1
Revenue, remaining performance obligation, expected timing of satisfaction, period 2 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2031-01-01  
Disaggregation of Revenue [Line Items]  
Fixed performance obligations $ 2
Revenue, remaining performance obligation, expected timing of satisfaction, period
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2031-01-01 | APCo  
Disaggregation of Revenue [Line Items]  
Fixed performance obligations $ 2
Revenue, remaining performance obligation, expected timing of satisfaction, period
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2031-01-01 | I&M  
Disaggregation of Revenue [Line Items]  
Fixed performance obligations $ 1
Revenue, remaining performance obligation, expected timing of satisfaction, period