VARIABLE INTEREST ENTITIES AND EQUITY METHOD INVESTMENTS - VIE Consolidation (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
ASSETS
Current Assets	$ 5,788.8	$ 6,082.1
Net Property, Plant and Equipment	82,415.6	76,693.4
Other Noncurrent Assets	14,873.6	13,908.5
TOTAL ASSETS	103,078.0	96,684.0
LIABILITIES AND EQUITY
Current Liabilities	13,009.3	11,583.6
Noncurrent Liabilities	63,044.8	59,772.0
Equity	26,986.1	25,285.9	$ 24,122.4	$ 22,680.2
TOTAL LIABILITIES, MEZZANINE EQUITY AND EQUITY	103,078.0	96,684.0
SOUTHWESTERN ELECTRIC POWER COMPANY
ASSETS
Current Assets	438.0	541.3
Net Property, Plant and Equipment	9,446.1	8,558.4
Other Noncurrent Assets	1,610.9	1,457.9
TOTAL ASSETS	11,495.0	10,557.6
LIABILITIES AND EQUITY
Current Liabilities	1,031.6	686.9
Noncurrent Liabilities	6,558.4	6,100.3
Equity	3,905.0	3,770.4	$ 3,674.8	$ 3,149.8
TOTAL LIABILITIES, MEZZANINE EQUITY AND EQUITY	11,495.0	10,557.6
INDIANA MICHIGAN POWER COMPANY
ASSETS
Current Assets	543.6	528.0
Net Property, Plant and Equipment	7,679.3	7,629.0
Other Noncurrent Assets	5,312.6	4,651.0
TOTAL ASSETS	13,535.5	12,808.0
LIABILITIES AND EQUITY
Current Liabilities	1,071.2	830.2
Noncurrent Liabilities	9,067.8	8,837.6
TOTAL LIABILITIES, MEZZANINE EQUITY AND EQUITY	13,535.5	12,808.0
AEP TEXAS INC.
ASSETS
Current Assets	500.4	520.1
Net Property, Plant and Equipment	14,043.5	12,774.0
Other Noncurrent Assets	655.7	696.6
TOTAL ASSETS	15,199.6	13,990.7
LIABILITIES AND EQUITY
Current Liabilities	1,407.1	749.4
Noncurrent Liabilities	8,907.9	8,445.2
TOTAL LIABILITIES, MEZZANINE EQUITY AND EQUITY	15,199.6	13,990.7
APPALACHIAN POWER COMPANY
ASSETS
Current Assets	1,094.9	1,059.0
Net Property, Plant and Equipment	13,612.5	12,931.5
Other Noncurrent Assets	1,958.5	1,721.4
TOTAL ASSETS	16,665.9	15,711.9
LIABILITIES AND EQUITY
Current Liabilities	2,025.5	1,685.9
Noncurrent Liabilities	8,892.4	8,749.3
TOTAL LIABILITIES, MEZZANINE EQUITY AND EQUITY	16,665.9	15,711.9
Variable Interest Entity, Primary Beneficiary | AEP Credit
ASSETS
Current Assets	1,118.3	1,208.8
Net Property, Plant and Equipment	0.0	0.0
Other Noncurrent Assets	10.5	9.6
TOTAL ASSETS	1,128.8	1,218.4
LIABILITIES AND EQUITY
Current Liabilities	1,068.8	1,155.0
Noncurrent Liabilities	1.0	0.9
Equity	59.0	62.5
TOTAL LIABILITIES, MEZZANINE EQUITY AND EQUITY	1,128.8	1,218.4
Variable Interest Entity, Primary Beneficiary | Protected Cell of EIS
ASSETS
Current Assets	218.5	205.3
Net Property, Plant and Equipment	0.0	0.0
Other Noncurrent Assets	0.0	0.0
TOTAL ASSETS	218.5	205.3
LIABILITIES AND EQUITY
Current Liabilities	54.7	49.2
Noncurrent Liabilities	96.0	91.7
Equity	67.8	64.4
TOTAL LIABILITIES, MEZZANINE EQUITY AND EQUITY	218.5	205.3
Variable Interest Entity, Primary Beneficiary | Transource Energy
ASSETS
Current Assets	40.2	36.9
Net Property, Plant and Equipment	598.3	533.4
Other Noncurrent Assets	3.5	5.1
TOTAL ASSETS	642.0	575.4
LIABILITIES AND EQUITY
Current Liabilities	57.2	45.3
Noncurrent Liabilities	274.3	241.5
Equity	310.5	288.6
TOTAL LIABILITIES, MEZZANINE EQUITY AND EQUITY	642.0	575.4
Variable Interest Entity, Primary Beneficiary | SOUTHWESTERN ELECTRIC POWER COMPANY | Sabine
ASSETS
Current Assets	6.0	4.2
Net Property, Plant and Equipment	0.0	0.0
Other Noncurrent Assets	110.8	150.7
TOTAL ASSETS	116.8	154.9
LIABILITIES AND EQUITY
Current Liabilities	20.1	19.9
Noncurrent Liabilities	96.3	134.8
Equity	0.4	0.2
TOTAL LIABILITIES, MEZZANINE EQUITY AND EQUITY	116.8	154.9
Variable Interest Entity, Primary Beneficiary | SOUTHWESTERN ELECTRIC POWER COMPANY | SWEPCo Storm Recovery Funding
ASSETS
Current Assets	3.4
Net Property, Plant and Equipment	0.0
Other Noncurrent Assets	331.4
TOTAL ASSETS	334.8
LIABILITIES AND EQUITY
Current Liabilities	24.4
Noncurrent Liabilities	308.7
Equity	1.7
TOTAL LIABILITIES, MEZZANINE EQUITY AND EQUITY	334.8
Variable Interest Entity, Primary Beneficiary | INDIANA MICHIGAN POWER COMPANY | DCC Fuel
ASSETS
Current Assets	79.3	81.9
Net Property, Plant and Equipment	132.3	153.8
Other Noncurrent Assets	63.6	81.7
TOTAL ASSETS	275.2	317.4
LIABILITIES AND EQUITY
Current Liabilities	79.2	81.7
Noncurrent Liabilities	196.0	235.7
Equity	0.0	0.0
TOTAL LIABILITIES, MEZZANINE EQUITY AND EQUITY	275.2	317.4
Variable Interest Entity, Primary Beneficiary | AEP TEXAS INC. | AEP Texas Transition Funding
ASSETS
Current Assets		25.5
Net Property, Plant and Equipment		0.0
Other Noncurrent Assets		71.4
TOTAL ASSETS		96.9
LIABILITIES AND EQUITY
Current Liabilities		75.5
Noncurrent Liabilities		17.0
Equity		4.4
TOTAL LIABILITIES, MEZZANINE EQUITY AND EQUITY		96.9
Variable Interest Entity, Primary Beneficiary | AEP TEXAS INC. | AEP Texas Restoration Funding
ASSETS
Current Assets	21.3	27.5
Net Property, Plant and Equipment	0.0	0.0
Other Noncurrent Assets	121.9	145.6
TOTAL ASSETS	143.2	173.1
LIABILITIES AND EQUITY
Current Liabilities	30.7	36.8
Noncurrent Liabilities	111.2	135.1
Equity	1.3	1.2
TOTAL LIABILITIES, MEZZANINE EQUITY AND EQUITY	143.2	173.1
Variable Interest Entity, Primary Beneficiary | AEP TEXAS INC. | Other Noncurrent Assets | AEP Texas Transition Funding
LIABILITIES AND EQUITY
Intercompany item eliminated in consolidation	5.0	8.0
Variable Interest Entity, Primary Beneficiary | AEP TEXAS INC. | Other Noncurrent Assets | AEP Texas Restoration Funding
LIABILITIES AND EQUITY
Intercompany item eliminated in consolidation	1.0	6.0
Variable Interest Entity, Primary Beneficiary | APPALACHIAN POWER COMPANY | APCo Appalachian Consumer Rate Relief Funding
ASSETS
Current Assets	14.2	13.3
Net Property, Plant and Equipment	0.0	0.0
Other Noncurrent Assets	109.6	138.2
TOTAL ASSETS	123.8	151.5
LIABILITIES AND EQUITY
Current Liabilities	30.5	29.9
Noncurrent Liabilities	91.4	119.7
Equity	1.9	1.9
TOTAL LIABILITIES, MEZZANINE EQUITY AND EQUITY	$ 123.8	151.5
Variable Interest Entity, Primary Beneficiary | APPALACHIAN POWER COMPANY | Other Noncurrent Assets | APCo Appalachian Consumer Rate Relief Funding
LIABILITIES AND EQUITY
Intercompany item eliminated in consolidation		$ 2.0