REVENUE FROM CONTRACTS WITH CUSTOMERS - Performance Obligation (Details) $ in Millions	Dec. 31, 2024 USD ($)
Disaggregation of Revenue [Line Items]
Fixed Performance Obligations	$ 301.6
APPALACHIAN POWER COMPANY
Disaggregation of Revenue [Line Items]
Fixed Performance Obligations	82.9
INDIANA MICHIGAN POWER COMPANY
Disaggregation of Revenue [Line Items]
Fixed Performance Obligations	22.4
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01
Disaggregation of Revenue [Line Items]
Fixed Performance Obligations	$ 93.7
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01 | APPALACHIAN POWER COMPANY
Disaggregation of Revenue [Line Items]
Fixed Performance Obligations	$ 16.1
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2025-01-01 | INDIANA MICHIGAN POWER COMPANY
Disaggregation of Revenue [Line Items]
Fixed Performance Obligations	$ 4.4
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01
Disaggregation of Revenue [Line Items]
Fixed Performance Obligations	$ 143.0
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	2 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01 | APPALACHIAN POWER COMPANY
Disaggregation of Revenue [Line Items]
Fixed Performance Obligations	$ 32.1
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	2 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2026-01-01 | INDIANA MICHIGAN POWER COMPANY
Disaggregation of Revenue [Line Items]
Fixed Performance Obligations	$ 8.8
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	2 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2028-01-01
Disaggregation of Revenue [Line Items]
Fixed Performance Obligations	$ 48.8
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	2 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2028-01-01 | APPALACHIAN POWER COMPANY
Disaggregation of Revenue [Line Items]
Fixed Performance Obligations	$ 23.1
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	2 years
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2028-01-01 | INDIANA MICHIGAN POWER COMPANY
Disaggregation of Revenue [Line Items]
Fixed Performance Obligations	$ 6.8
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	$ 16.1
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2029-01-01 | APPALACHIAN POWER COMPANY
Disaggregation of Revenue [Line Items]
Fixed Performance Obligations	$ 11.6
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2029-01-01 | INDIANA MICHIGAN POWER COMPANY
Disaggregation of Revenue [Line Items]
Fixed Performance Obligations	$ 2.4
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period