INCOME TAXES - Reconciliations to Federal Income Tax (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Effective Income Tax Rate Reconciliation [Line Items]
Net Income	$ 2,975.8	$ 2,212.6	$ 2,305.6
Less: Equity Earnings	(93.7)	(58.5)	109.4
Income Tax Expense (Benefit)	(39.2)	54.6	5.4
Pretax Income	2,935.2	2,265.8	2,309.6
Income Taxes on Pretax Income at Statutory Rate (21%)	$ 616.5	$ 475.8	$ 485.0
Statutory rate	21.00%	21.00%	21.00%
Increase (Decrease) in Income Taxes Resulting from the Following Items:
Reversal of Origination Flow-Through	$ 20.5	$ 26.0	$ 17.1
Investment Tax Credit Amortization	(58.4)	(50.3)	(14.3)
Production Tax Credits	(214.2)	(175.2)	(197.1)
State and Local Income Taxes, Net	16.7	43.7	(14.0)
Removal Costs	(14.6)	(22.0)	(26.5)
AFUDC Equity	(46.5)	(39.8)	(29.3)
Tax Reform Excess ADIT Reversal	(91.6)	(151.1)	(214.5)
Remeasurement of Excess ADIT	(262.2)	(46.0)
Federal Return to Provision		0.0	(17.4)
Disallowance Cost		0.0
Other	(5.4)	(6.5)	16.4
Income Tax Expense (Benefit)	$ (39.2)	$ 54.6	$ 5.4
Effective Income Tax Rate	(1.30%)	2.40%	0.20%
Dolet Hills Lignite Co, LLC
Effective Income Tax Rate Reconciliation [Line Items]
Less: Equity Earnings	$ (1.4)	$ (1.4)	$ (1.4)
AEP TEXAS INC.
Effective Income Tax Rate Reconciliation [Line Items]
Net Income	420.1	370.4	307.9
Income Tax Expense (Benefit)	102.1	85.9	72.6
Pretax Income	522.2	456.3	380.5
Income Taxes on Pretax Income at Statutory Rate (21%)	109.7	95.8	79.9
Increase (Decrease) in Income Taxes Resulting from the Following Items:
Reversal of Origination Flow-Through	0.8	0.6	0.0
Investment Tax Credit Amortization	(0.9)	(0.7)	0.0
Production Tax Credits	0.0	0.0	0.0
State and Local Income Taxes, Net	2.3	2.1	1.7
Removal Costs	0.0	0.0	0.0
AFUDC Equity	(9.6)	(6.0)	(4.1)
Tax Reform Excess ADIT Reversal	(5.1)	(6.0)	(5.5)
Remeasurement of Excess ADIT	6.4	0.0
Federal Return to Provision		(0.1)	0.0
Disallowance Cost		0.0
Other	(1.5)	0.2	0.6
Income Tax Expense (Benefit)	$ 102.1	$ 85.9	$ 72.6
Effective Income Tax Rate	19.60%	18.80%	19.10%
AEP TEXAS INC. | Investment funds
Effective Income Tax Rate Reconciliation [Line Items]
Less: Equity Earnings	$ 0.0	$ 0.0	$ 0.0
AEP TRANSMISSION COMPANY, LLC
Effective Income Tax Rate Reconciliation [Line Items]
Net Income	688.4	614.2	594.2
Income Tax Expense (Benefit)	190.3	147.1	169.1
Pretax Income	878.7	761.3	763.3
Income Taxes on Pretax Income at Statutory Rate (21%)	184.5	159.9	160.3
Increase (Decrease) in Income Taxes Resulting from the Following Items:
Reversal of Origination Flow-Through	2.7	2.4	0.0
Investment Tax Credit Amortization	0.0	0.0	0.0
Production Tax Credits	0.0	0.0	0.0
State and Local Income Taxes, Net	20.5	0.7	19.8
Removal Costs	0.0	0.0	0.0
AFUDC Equity	(18.8)	(17.5)	(14.8)
Tax Reform Excess ADIT Reversal	1.6	1.7	0.0
Remeasurement of Excess ADIT	0.0	0.0
Federal Return to Provision		0.0	0.0
Disallowance Cost		0.0
Other	(0.2)	(0.1)	3.8
Income Tax Expense (Benefit)	$ 190.3	$ 147.1	$ 169.1
Effective Income Tax Rate	21.70%	19.30%	22.20%
AEP TRANSMISSION COMPANY, LLC | Investment funds
Effective Income Tax Rate Reconciliation [Line Items]
Less: Equity Earnings	$ 0.0	$ 0.0	$ 0.0
APPALACHIAN POWER COMPANY
Effective Income Tax Rate Reconciliation [Line Items]
Net Income	421.7	294.4	394.2
Income Tax Expense (Benefit)	75.1	14.2	18.2
Pretax Income	496.8	308.6	412.4
Income Taxes on Pretax Income at Statutory Rate (21%)	104.3	64.8	86.6
Increase (Decrease) in Income Taxes Resulting from the Following Items:
Reversal of Origination Flow-Through	6.6	9.9	4.7
Investment Tax Credit Amortization	0.1	0.0	0.0
Production Tax Credits	(0.3)	(0.1)	0.0
State and Local Income Taxes, Net	10.3	9.9	(5.9)
Removal Costs	(11.2)	(5.1)	(9.8)
AFUDC Equity	(5.3)	(5.5)	(3.7)
Tax Reform Excess ADIT Reversal	(30.1)	(17.3)	(50.9)
Remeasurement of Excess ADIT	0.0	(46.0)
Federal Return to Provision		3.4	(2.8)
Disallowance Cost		0.0
Other	0.7	0.2	0.0
Income Tax Expense (Benefit)	$ 75.1	$ 14.2	$ 18.2
Effective Income Tax Rate	15.10%	4.60%	4.40%
APPALACHIAN POWER COMPANY | Investment funds
Effective Income Tax Rate Reconciliation [Line Items]
Less: Equity Earnings	$ 0.0	$ 0.0	$ 0.0
INDIANA MICHIGAN POWER COMPANY
Effective Income Tax Rate Reconciliation [Line Items]
Net Income	391.4	335.9	324.7
Income Tax Expense (Benefit)	(95.2)	58.6	4.2
Pretax Income	296.2	394.5	328.9
Income Taxes on Pretax Income at Statutory Rate (21%)	62.2	82.8	69.1
Increase (Decrease) in Income Taxes Resulting from the Following Items:
Reversal of Origination Flow-Through	4.0	6.4	2.9
Investment Tax Credit Amortization	(2.0)	(1.6)	(3.1)
Production Tax Credits	(69.0)	0.0	0.0
State and Local Income Taxes, Net	5.5	17.5	9.6
Removal Costs	(3.7)	(11.8)	(12.4)
AFUDC Equity	(2.8)	(2.3)	(2.1)
Tax Reform Excess ADIT Reversal	(15.5)	(30.0)	(54.0)
Remeasurement of Excess ADIT	(73.3)	0.0
Federal Return to Provision		(2.5)	(6.2)
Disallowance Cost		0.0
Other	(0.6)	0.1	0.4
Income Tax Expense (Benefit)	$ (95.2)	$ 58.6	$ 4.2
Effective Income Tax Rate	(32.10%)	14.90%	1.30%
INDIANA MICHIGAN POWER COMPANY | Investment funds
Effective Income Tax Rate Reconciliation [Line Items]
Less: Equity Earnings	$ 0.0	$ 0.0	$ 0.0
OHIO POWER COMPANY
Effective Income Tax Rate Reconciliation [Line Items]
Net Income	305.6	328.2	287.8
Less: Equity Earnings	1.1	0.0	(0.6)
Income Tax Expense (Benefit)	52.4	54.3	44.2
Pretax Income	358.0	382.5	331.4
Income Taxes on Pretax Income at Statutory Rate (21%)	75.2	80.3	69.6
Increase (Decrease) in Income Taxes Resulting from the Following Items:
Reversal of Origination Flow-Through	2.7	2.6	3.0
Investment Tax Credit Amortization	0.1	0.0	0.0
Production Tax Credits	0.0	0.0	0.0
State and Local Income Taxes, Net	10.7	3.9	(1.6)
Removal Costs	0.0	0.0	0.0
AFUDC Equity	(4.9)	(3.6)	(2.9)
Tax Reform Excess ADIT Reversal	(31.1)	(28.9)	(27.5)
Remeasurement of Excess ADIT	0.0	0.0
Federal Return to Provision		(0.4)	3.5
Disallowance Cost		0.0
Other	(0.3)	0.4	0.1
Income Tax Expense (Benefit)	$ 52.4	$ 54.3	$ 44.2
Effective Income Tax Rate	14.60%	14.20%	13.30%
OHIO POWER COMPANY | Investment funds
Effective Income Tax Rate Reconciliation [Line Items]
Less: Equity Earnings	$ 0.0	$ 0.0	$ (0.6)
PUBLIC SERVICE COMPANY OF OKLAHOMA
Effective Income Tax Rate Reconciliation [Line Items]
Net Income	249.3	208.8	167.6
Income Tax Expense (Benefit)	(99.6)	(53.6)	(49.2)
Pretax Income	149.7	155.2	118.4
Income Taxes on Pretax Income at Statutory Rate (21%)	31.4	32.6	24.9
Increase (Decrease) in Income Taxes Resulting from the Following Items:
Reversal of Origination Flow-Through	0.4	0.4	0.0
Investment Tax Credit Amortization	(1.4)	(1.4)	(1.6)
Production Tax Credits	(73.8)	(64.3)	(47.7)
State and Local Income Taxes, Net	(0.6)	3.5	4.3
Removal Costs	0.0	0.0	0.0
AFUDC Equity	(1.6)	(1.8)	0.0
Tax Reform Excess ADIT Reversal	(5.5)	(23.3)	(25.4)
Remeasurement of Excess ADIT	(48.6)	0.0
Federal Return to Provision		0.6	(3.7)
Disallowance Cost		0.0
Other	0.1	0.1	0.0
Income Tax Expense (Benefit)	$ (99.6)	$ (53.6)	$ (49.2)
Effective Income Tax Rate	(66.50%)	(34.50%)	(41.60%)
PUBLIC SERVICE COMPANY OF OKLAHOMA | Investment funds
Effective Income Tax Rate Reconciliation [Line Items]
Less: Equity Earnings	$ 0.0	$ 0.0	$ 0.0
SOUTHWESTERN ELECTRIC POWER COMPANY
Effective Income Tax Rate Reconciliation [Line Items]
Net Income	325.7	223.8	294.3
Less: Equity Earnings	(1.4)	(1.4)	(1.4)
Income Tax Expense (Benefit)	(184.0)	(33.3)	(25.2)
Pretax Income	140.3	189.1	267.7
Income Taxes on Pretax Income at Statutory Rate (21%)	29.5	39.7	56.2
Increase (Decrease) in Income Taxes Resulting from the Following Items:
Reversal of Origination Flow-Through	2.1	2.1	2.3
Investment Tax Credit Amortization	(0.1)	(0.2)	0.0
Production Tax Credits	(70.7)	(67.1)	(57.1)
State and Local Income Taxes, Net	10.6	(4.0)	(4.9)
Removal Costs	0.0	0.0	0.0
AFUDC Equity	(2.8)	(2.4)	0.0
Tax Reform Excess ADIT Reversal	(4.0)	(12.6)	(14.8)
Remeasurement of Excess ADIT	(146.8)	0.0
Federal Return to Provision		1.0	0.0
Disallowance Cost		12.0
Other	(1.8)	(1.8)	(6.9)
Income Tax Expense (Benefit)	$ (184.0)	$ (33.3)	$ (25.2)
Effective Income Tax Rate	(131.10%)	(17.60%)	(9.40%)
SOUTHWESTERN ELECTRIC POWER COMPANY | Dolet Hills Lignite Co, LLC
Effective Income Tax Rate Reconciliation [Line Items]
Less: Equity Earnings	$ (1.4)	$ (1.4)	$ (1.4)