RATE MATTERS - Regulatory Assets Subject to Securitization (Details) - APPALACHIAN POWER COMPANY - USD ($) $ in Millions	Sep. 30, 2026	Aug. 31, 2026	Jul. 31, 2026
Regulatory Asset [Line Items]
Regulatory asset, approved to be financed through securitization	$ 2,708
Undepreciated Utility Plant Balances of Amos, Mitchell and Mountaineer (as of December 31, 2022)
Regulatory Asset [Line Items]
Regulatory asset, approved to be financed through securitization	1,704
ENEC Under-Recovery Regulatory Assets
Regulatory Asset [Line Items]
Regulatory asset, approved to be financed through securitization	593
Forecasted Undepreciated CCR and ELG Investments of Amos, Mitchell and Mountaineer (as of November 30, 2024)
Regulatory Asset [Line Items]
Regulatory asset, approved to be financed through securitization	237
Deferred Storm Other Operation and Maintenance Expense Regulatory Assets
Regulatory Asset [Line Items]
Regulatory asset, approved to be financed through securitization	158
Upfront Financing Costs
Regulatory Asset [Line Items]
Regulatory asset, approved to be financed through securitization	16
ENEC Filing \| 8/31/2026 Under-Recovery ENEC Balance
Regulatory Asset [Line Items]
Regulatory asset, approved to be financed through securitization		$ 9	$ 593
ENEC Filing \| ENEC Under-Recovery Regulatory Assets
Regulatory Asset [Line Items]
Regulatory asset, approved to be financed through securitization			2,700
APCo Portion
Regulatory Asset [Line Items]
Regulatory asset, approved to be financed through securitization	1,672
APCo Portion \| Undepreciated Utility Plant Balances of Amos, Mitchell and Mountaineer (as of December 31, 2022)
Regulatory Asset [Line Items]
Regulatory asset, approved to be financed through securitization	1,145
APCo Portion \| ENEC Under-Recovery Regulatory Assets
Regulatory Asset [Line Items]
Regulatory asset, approved to be financed through securitization	274
APCo Portion \| Forecasted Undepreciated CCR and ELG Investments of Amos, Mitchell and Mountaineer (as of November 30, 2024)
Regulatory Asset [Line Items]
Regulatory asset, approved to be financed through securitization	88
APCo Portion \| Deferred Storm Other Operation and Maintenance Expense Regulatory Assets
Regulatory Asset [Line Items]
Regulatory asset, approved to be financed through securitization	155
APCo Portion \| Upfront Financing Costs
Regulatory Asset [Line Items]
Regulatory asset, approved to be financed through securitization	10
APCo Portion \| ENEC Filing \| 8/31/2026 Under-Recovery ENEC Balance
Regulatory Asset [Line Items]
Regulatory asset, approved to be financed through securitization			274
APCo Portion \| ENEC Filing \| ENEC Under-Recovery Regulatory Assets
Regulatory Asset [Line Items]
Regulatory asset, approved to be financed through securitization			$ 1,700
WPCo Portion
Regulatory Asset [Line Items]
Regulatory asset, approved to be financed through securitization	1,036
WPCo Portion \| Undepreciated Utility Plant Balances of Amos, Mitchell and Mountaineer (as of December 31, 2022)
Regulatory Asset [Line Items]
Regulatory asset, approved to be financed through securitization	559
WPCo Portion \| ENEC Under-Recovery Regulatory Assets
Regulatory Asset [Line Items]
Regulatory asset, approved to be financed through securitization	319
WPCo Portion \| Forecasted Undepreciated CCR and ELG Investments of Amos, Mitchell and Mountaineer (as of November 30, 2024)
Regulatory Asset [Line Items]
Regulatory asset, approved to be financed through securitization	149
WPCo Portion \| Deferred Storm Other Operation and Maintenance Expense Regulatory Assets
Regulatory Asset [Line Items]
Regulatory asset, approved to be financed through securitization	3
WPCo Portion \| Upfront Financing Costs
Regulatory Asset [Line Items]
Regulatory asset, approved to be financed through securitization	$ 6