RATE MATTERS - Impact to the Statements of Income Recorded by the Registrants (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2025	Jun. 30, 2025	Mar. 31, 2025	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2025	Sep. 30, 2024
Regulatory Asset [Line Items]
Total Revenues	$ 6,010.4			$ 5,420.1			$ 16,560.7	$ 15,025.0
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation	(1,980.2)			(1,659.2)			(5,374.5)	(4,603.5)
INCOME (LOSS) BEFORE INCOME TAX EXPENSE (BENEFIT)	1,117.9			981.9			3,024.2	2,145.2
Income Tax Expense (Benefit)	138.7			37.5			13.3	(97.7)
Net Income	1,000.3	$ 1,288.3	$ 802.2	961.7	$ 342.5	$ 1,005.7	3,090.8	2,309.9
Net Income Attributable to Noncontrolling Interest	28.3			2.1			92.8	6.9
EARNINGS (LOSS) ATTRIBUTABLE TO COMMON SHAREHOLDERS, Basic	972.0			959.6			2,998.0	2,303.0
EARNINGS (LOSS) ATTRIBUTABLE TO COMMON SHAREHOLDERS, Diluted	972.0			959.6			2,998.0	2,303.0
FERC 2021 PJM and SPP Transmission Formula Rate Challenge
Regulatory Asset [Line Items]
Total Revenues		270.5
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation		(23.9)
Other Operation		53.0
INCOME (LOSS) BEFORE INCOME TAX EXPENSE (BENEFIT)		241.4
Income Tax Expense (Benefit)		(312.8)
Net Income		554.2
Net Income Attributable to Noncontrolling Interest		55.2
EARNINGS (LOSS) ATTRIBUTABLE TO COMMON SHAREHOLDERS, Basic		499.0
EARNINGS (LOSS) ATTRIBUTABLE TO COMMON SHAREHOLDERS, Diluted		499.0
AEPTCo
Regulatory Asset [Line Items]
Total Revenues	558.0			497.2			1,826.9	1,455.2
INCOME (LOSS) BEFORE INCOME TAX EXPENSE (BENEFIT)	261.7			245.0			1,005.2	701.7
Income Tax Expense (Benefit)	56.2			53.7			(28.3)	153.5
Net Income	205.5	616.5	211.5	191.3	175.7	181.2	1,033.5	548.2
Net Income Attributable to Noncontrolling Interest	26.6			0.0			87.3	0.0
EARNINGS (LOSS) ATTRIBUTABLE TO COMMON SHAREHOLDERS, Basic	178.9			191.3			946.2	548.2
EARNINGS (LOSS) ATTRIBUTABLE TO COMMON SHAREHOLDERS, Diluted	178.9			191.3			946.2	548.2
AEPTCo | FERC 2021 PJM and SPP Transmission Formula Rate Challenge
Regulatory Asset [Line Items]
Total Revenues		214.3
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation		0.0
Other Operation		0.0
INCOME (LOSS) BEFORE INCOME TAX EXPENSE (BENEFIT)		214.3
Income Tax Expense (Benefit)		(203.2)
Net Income		417.5
Net Income Attributable to Noncontrolling Interest		55.2
EARNINGS (LOSS) ATTRIBUTABLE TO COMMON SHAREHOLDERS, Basic		362.3
EARNINGS (LOSS) ATTRIBUTABLE TO COMMON SHAREHOLDERS, Diluted		362.3
APCo
Regulatory Asset [Line Items]
Total Revenues	1,056.0			1,028.9			3,176.5	3,032.1
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation	(374.1)			(358.4)			(1,072.1)	(1,060.0)
INCOME (LOSS) BEFORE INCOME TAX EXPENSE (BENEFIT)	112.8			132.3			411.3	353.8
Income Tax Expense (Benefit)	31.7			22.5			58.7	49.2
APCo | FERC 2021 PJM and SPP Transmission Formula Rate Challenge
Regulatory Asset [Line Items]
Total Revenues		5.6
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation		(17.2)
Other Operation		14.8
INCOME (LOSS) BEFORE INCOME TAX EXPENSE (BENEFIT)		8.0
Income Tax Expense (Benefit)		(21.4)
Net Income		29.4
Net Income Attributable to Noncontrolling Interest		0.0
EARNINGS (LOSS) ATTRIBUTABLE TO COMMON SHAREHOLDERS, Basic		29.4
EARNINGS (LOSS) ATTRIBUTABLE TO COMMON SHAREHOLDERS, Diluted		29.4
I&M
Regulatory Asset [Line Items]
Total Revenues	812.2			733.5			2,271.6	1,995.2
INCOME (LOSS) BEFORE INCOME TAX EXPENSE (BENEFIT)	138.6			135.0			295.7	266.4
Income Tax Expense (Benefit)	(11.1)			(44.1)			(35.6)	(92.9)
I&M | FERC 2021 PJM and SPP Transmission Formula Rate Challenge
Regulatory Asset [Line Items]
Total Revenues		10.8
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation		0.0
Other Operation		(6.0)
INCOME (LOSS) BEFORE INCOME TAX EXPENSE (BENEFIT)		16.8
Income Tax Expense (Benefit)		(27.8)
Net Income		44.6
Net Income Attributable to Noncontrolling Interest		0.0
EARNINGS (LOSS) ATTRIBUTABLE TO COMMON SHAREHOLDERS, Basic		44.6
EARNINGS (LOSS) ATTRIBUTABLE TO COMMON SHAREHOLDERS, Diluted		44.6
OPCo
Regulatory Asset [Line Items]
Total Revenues	1,070.2			1,004.2			2,992.7	2,924.3
INCOME (LOSS) BEFORE INCOME TAX EXPENSE (BENEFIT)	122.7			132.5			324.0	232.9
Income Tax Expense (Benefit)	21.9			19.8			58.8	30.4
OPCo | FERC 2021 PJM and SPP Transmission Formula Rate Challenge
Regulatory Asset [Line Items]
Total Revenues		0.0
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation		0.0
Other Operation		0.1
INCOME (LOSS) BEFORE INCOME TAX EXPENSE (BENEFIT)		(0.1)
Income Tax Expense (Benefit)		0.0
Net Income		(0.1)
Net Income Attributable to Noncontrolling Interest		0.0
EARNINGS (LOSS) ATTRIBUTABLE TO COMMON SHAREHOLDERS, Basic		(0.1)
EARNINGS (LOSS) ATTRIBUTABLE TO COMMON SHAREHOLDERS, Diluted		(0.1)
PSO
Regulatory Asset [Line Items]
Total Revenues	693.4			615.4			1,556.9	1,462.0
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation	(294.2)			(284.8)			(595.5)	(613.7)
INCOME (LOSS) BEFORE INCOME TAX EXPENSE (BENEFIT)	98.1			78.2			157.1	119.8
Income Tax Expense (Benefit)	(31.7)			(35.5)			(63.9)	(102.2)
PSO | FERC 2021 PJM and SPP Transmission Formula Rate Challenge
Regulatory Asset [Line Items]
Total Revenues		6.4
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation		0.0
Other Operation		18.8
INCOME (LOSS) BEFORE INCOME TAX EXPENSE (BENEFIT)		(12.4)
Income Tax Expense (Benefit)		(15.6)
Net Income		3.2
Net Income Attributable to Noncontrolling Interest		0.0
EARNINGS (LOSS) ATTRIBUTABLE TO COMMON SHAREHOLDERS, Basic		3.2
EARNINGS (LOSS) ATTRIBUTABLE TO COMMON SHAREHOLDERS, Diluted		3.2
SWEPCo
Regulatory Asset [Line Items]
Total Revenues	723.9			638.8			1,825.4	1,550.8
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation	(192.4)			(204.1)			(575.8)	(582.1)
INCOME (LOSS) BEFORE INCOME TAX EXPENSE (BENEFIT)	166.4			129.2			267.1	80.7
Income Tax Expense (Benefit)	(23.3)			(10.5)			(87.9)	(198.8)
Net Income	189.9	116.4	$ 49.5	140.1	$ (69.1)	$ 209.6	355.8	280.6
Net Income Attributable to Noncontrolling Interest	0.7			1.0			2.5	3.5
EARNINGS (LOSS) ATTRIBUTABLE TO COMMON SHAREHOLDERS, Basic	189.2			139.1			353.3	277.1
EARNINGS (LOSS) ATTRIBUTABLE TO COMMON SHAREHOLDERS, Diluted	$ 189.2			$ 139.1			$ 353.3	$ 277.1
SWEPCo | FERC 2021 PJM and SPP Transmission Formula Rate Challenge
Regulatory Asset [Line Items]
Total Revenues		26.9
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation		0.0
Other Operation		10.1
INCOME (LOSS) BEFORE INCOME TAX EXPENSE (BENEFIT)		16.8
Income Tax Expense (Benefit)		(38.9)
Net Income		55.7
Net Income Attributable to Noncontrolling Interest		0.0
EARNINGS (LOSS) ATTRIBUTABLE TO COMMON SHAREHOLDERS, Basic		55.7
EARNINGS (LOSS) ATTRIBUTABLE TO COMMON SHAREHOLDERS, Diluted		$ 55.7