BUSINESS SEGMENTS - Schedule of AEP's Reportable Segment Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Reportable Segment Information
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
Other Operation and Maintenance	1,202.9	1,149.5	3,202.1	3,398.1
Asset Impairments and Other Related Charges	0.0	0.0	0.0	142.5
Depreciation and Amortization	879.6	852.7	2,566.1	2,461.7
Taxes Other Than Income Taxes	426.3	407.2	1,213.3	1,211.2
Allowance for Equity Funds Used During Construction	58.5	54.2	172.9	153.0
Interest Expense	508.5	498.8	1,492.9	1,400.0
Income Tax Expense (Benefit)	138.7	37.5	13.3	(97.7)
Equity Earnings of Unconsolidated Subsidiaries	21.1	17.3	79.9	67.0
Other Segment Items	(18.2)	(72.9)	(46.7)	(177.3)
Earnings (Loss) Attributable to AEPTCo Common Shareholders, Basic	972.0	959.6	2,998.0	2,303.0
Earnings (Loss) Attributable to AEPTCo Common Shareholders, Diluted	972.0	959.6	2,998.0	2,303.0
Gross Property Additions	2,279.0	1,850.3	7,658.5	5,168.6
Total Assets	110,253.5		110,253.5		$ 103,078.0
Investments in Equity Method Investees	1,235.8		1,235.8		1,055.9
Nonrelated Party
Reportable Segment Information
Total Revenues	6,010.4	5,420.1	16,560.7	15,025.0
Related Party
Reportable Segment Information
Total Revenues	0.0	0.0	0.0	0.0
Operating Segments
Reportable Segment Information
Total Revenues	6,560.9	5,890.0	18,302.4	16,401.2
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation	2,057.1	1,727.2	5,595.4	4,850.3
Other Operation and Maintenance	1,710.4	1,541.3	4,806.3	4,576.4
Asset Impairments and Other Related Charges				142.5
Depreciation and Amortization	884.6	857.9	2,581.2	2,477.4
Taxes Other Than Income Taxes	420.0	401.7	1,194.8	1,196.0
Allowance for Equity Funds Used During Construction	58.5	54.2	172.9	153.0
Interest Expense	390.3	356.5	1,123.1	1,017.0
Income Tax Expense (Benefit)	109.1	22.6	84.3	(40.3)
Equity Earnings of Unconsolidated Subsidiaries	21.1	23.4	68.8	73.8
Other Segment Items	(21.0)	(64.3)	(53.8)	(181.8)
Earnings (Loss) Attributable to AEPTCo Common Shareholders, Basic	1,090.0	1,124.7	3,212.8	2,590.5
Earnings (Loss) Attributable to AEPTCo Common Shareholders, Diluted	1,090.0	1,124.7	3,212.8	2,590.5
Gross Property Additions	2,285.6	1,858.0	7,627.1	5,174.6
Total Assets	108,254.3		108,254.3		101,506.6
Investments in Equity Method Investees	1,070.3		1,070.3		1,007.2
Operating Segments | Nonrelated Party
Reportable Segment Information
Total Revenues	6,004.9	5,414.1	16,535.6	14,976.9
Operating Segments | Related Party
Reportable Segment Information
Total Revenues	556.0	475.9	1,766.8	1,424.3
Corporate and Other
Reportable Segment Information
Total Revenues	35.9	38.1	110.1	148.6
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation	0.0	0.0	0.0	0.0
Other Operation and Maintenance	8.1	53.6	44.4	114.6
Asset Impairments and Other Related Charges				0.0
Depreciation and Amortization	(5.0)	(5.2)	(15.1)	(15.7)
Taxes Other Than Income Taxes	0.2	0.1	0.8	0.3
Allowance for Equity Funds Used During Construction	0.0	0.0	0.0	0.0
Interest Expense	140.2	168.4	438.3	479.5
Income Tax Expense (Benefit)	29.6	14.9	(71.0)	(57.4)
Equity Earnings of Unconsolidated Subsidiaries	0.0	(6.1)	11.1	(6.8)
Other Segment Items	(19.2)	(34.7)	(61.4)	(92.0)
Earnings (Loss) Attributable to AEPTCo Common Shareholders, Basic	(118.0)	(165.1)	(214.8)	(287.5)
Earnings (Loss) Attributable to AEPTCo Common Shareholders, Diluted	(118.0)	(165.1)	(214.8)	(287.5)
Gross Property Additions	18.5	7.4	54.3	16.9
Total Assets	6,172.3		6,172.3		5,550.8
Investments in Equity Method Investees	165.5		165.5		48.7
Corporate and Other | Nonrelated Party
Reportable Segment Information
Total Revenues	5.5	6.0	25.1	48.1
Corporate and Other | Related Party
Reportable Segment Information
Total Revenues	30.4	32.1	85.0	100.5
Reconciling Adjustments
Reportable Segment Information
Total Revenues	(586.4)	(508.0)	(1,851.8)	(1,524.8)
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation	(76.9)	(68.0)	(220.9)	(246.8)
Other Operation and Maintenance	(515.6)	(445.4)	(1,648.6)	(1,292.9)
Asset Impairments and Other Related Charges				0.0
Depreciation and Amortization	0.0	0.0	0.0	0.0
Taxes Other Than Income Taxes	6.1	5.4	17.7	14.9
Allowance for Equity Funds Used During Construction	0.0	0.0	0.0	0.0
Interest Expense	(22.0)	(26.1)	(68.5)	(96.5)
Income Tax Expense (Benefit)	0.0	0.0	0.0	0.0
Equity Earnings of Unconsolidated Subsidiaries	0.0	0.0	0.0	0.0
Other Segment Items	22.0	26.1	68.5	96.5
Earnings (Loss) Attributable to AEPTCo Common Shareholders, Basic	0.0	0.0	0.0	0.0
Earnings (Loss) Attributable to AEPTCo Common Shareholders, Diluted	0.0	0.0	0.0	0.0
Gross Property Additions	(25.1)	(15.1)	(22.9)	(22.9)
Total Assets	(4,173.1)		(4,173.1)		(3,979.4)
Investments in Equity Method Investees	0.0		0.0		0.0
Reconciling Adjustments | Nonrelated Party
Reportable Segment Information
Total Revenues	0.0	0.0	0.0	0.0
Reconciling Adjustments | Related Party
Reportable Segment Information
Total Revenues	(586.4)	(508.0)	(1,851.8)	(1,524.8)
VIU | Operating Segments
Reportable Segment Information
Total Revenues	3,585.7	3,303.0	9,738.7	8,869.9
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation	1,168.4	1,100.4	3,164.3	2,970.3
Other Operation and Maintenance	998.2	881.6	2,863.4	2,720.1
Asset Impairments and Other Related Charges				13.4
Depreciation and Amortization	547.4	530.6	1,593.9	1,470.4
Taxes Other Than Income Taxes	141.6	138.1	398.1	410.7
Allowance for Equity Funds Used During Construction	19.4	12.9	51.8	37.4
Interest Expense	219.1	189.9	620.8	537.3
Income Tax Expense (Benefit)	(25.6)	(64.6)	(117.2)	(324.5)
Equity Earnings of Unconsolidated Subsidiaries	0.2	0.4	0.8	1.1
Other Segment Items	(22.0)	(31.2)	(67.0)	(87.3)
Earnings (Loss) Attributable to AEPTCo Common Shareholders, Basic	578.2	571.5	1,335.0	1,198.0
Earnings (Loss) Attributable to AEPTCo Common Shareholders, Diluted	578.2	571.5	1,335.0	1,198.0
Gross Property Additions	1,203.2	809.3	4,356.4	2,290.2
Total Assets	59,005.8		59,005.8		54,996.5
Investments in Equity Method Investees	8.8		8.8		9.1
VIU | Operating Segments | Nonrelated Party
Reportable Segment Information
Total Revenues	3,511.2	3,248.8	9,531.2	8,722.0
VIU | Operating Segments | Related Party
Reportable Segment Information
Total Revenues	74.5	54.2	207.5	147.9
T&D | Operating Segments
Reportable Segment Information
Total Revenues	1,689.3	1,575.4	4,666.0	4,501.5
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation	263.8	213.2	730.3	729.0
Other Operation and Maintenance	623.5	599.1	1,741.7	1,639.0
Asset Impairments and Other Related Charges				52.9
Depreciation and Amortization	209.8	212.8	614.2	662.2
Taxes Other Than Income Taxes	190.4	181.6	554.9	550.4
Allowance for Equity Funds Used During Construction	18.3	17.0	56.4	50.9
Interest Expense	106.4	106.4	318.0	298.4
Income Tax Expense (Benefit)	57.2	49.4	141.9	116.3
Equity Earnings of Unconsolidated Subsidiaries	0.1	0.0	1.5	(0.8)
Other Segment Items	(11.0)	(15.3)	(33.2)	(38.9)
Earnings (Loss) Attributable to AEPTCo Common Shareholders, Basic	267.6	245.2	656.1	542.3
Earnings (Loss) Attributable to AEPTCo Common Shareholders, Diluted	267.6	245.2	656.1	542.3
Gross Property Additions	711.2	609.7	2,078.9	1,730.8
Total Assets	28,429.9		28,429.9		26,864.3
Investments in Equity Method Investees	3.6		3.6		2.0
T&D | Operating Segments | Nonrelated Party
Reportable Segment Information
Total Revenues	1,680.2	1,568.5	4,638.3	4,480.5
T&D | Operating Segments | Related Party
Reportable Segment Information
Total Revenues	9.1	6.9	27.7	21.0
AEPTHCo | Operating Segments
Reportable Segment Information
Total Revenues	573.2	512.5	1,871.9	1,499.7
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation	0.0	0.0	0.0	0.0
Other Operation and Maintenance	53.3	40.0	135.7	122.8
Asset Impairments and Other Related Charges				0.0
Depreciation and Amortization	123.5	110.5	360.8	327.5
Taxes Other Than Income Taxes	87.3	81.2	240.1	233.4
Allowance for Equity Funds Used During Construction	20.8	24.3	64.7	64.7
Interest Expense	63.3	56.2	178.9	166.4
Income Tax Expense (Benefit)	62.0	60.9	(10.4)	172.2
Equity Earnings of Unconsolidated Subsidiaries	20.8	23.0	66.5	72.6
Other Segment Items	25.5	(3.7)	85.1	(9.4)
Earnings (Loss) Attributable to AEPTCo Common Shareholders, Basic	199.9	214.7	1,012.9	624.1
Earnings (Loss) Attributable to AEPTCo Common Shareholders, Diluted	199.9	214.7	1,012.9	624.1
Gross Property Additions	368.0	425.8	1,181.9	1,120.4
Total Assets	18,918.9		18,918.9		18,011.9
Investments in Equity Method Investees	1,057.9		1,057.9		996.1
AEPTHCo | Operating Segments | Nonrelated Party
Reportable Segment Information
Total Revenues	119.7	113.1	390.7	332.3
AEPTHCo | Operating Segments | Related Party
Reportable Segment Information
Total Revenues	453.5	399.4	1,481.2	1,167.4
G&M | Operating Segments
Reportable Segment Information
Total Revenues	712.7	499.1	2,025.8	1,530.1
Purchased Electricity, Fuel and Other Consumables Used for Electric Generation	624.9	413.6	1,700.8	1,151.0
Other Operation and Maintenance	35.4	20.6	65.5	94.5
Asset Impairments and Other Related Charges				76.2
Depreciation and Amortization	3.9	4.0	12.3	17.3
Taxes Other Than Income Taxes	0.7	0.8	1.7	1.5
Allowance for Equity Funds Used During Construction	0.0	0.0	0.0	0.0
Interest Expense	1.5	4.0	5.4	14.9
Income Tax Expense (Benefit)	15.5	(23.1)	70.0	(4.3)
Equity Earnings of Unconsolidated Subsidiaries	0.0	0.0	0.0	0.9
Other Segment Items	(13.5)	(14.1)	(38.7)	(46.2)
Earnings (Loss) Attributable to AEPTCo Common Shareholders, Basic	44.3	93.3	208.8	226.1
Earnings (Loss) Attributable to AEPTCo Common Shareholders, Diluted	44.3	93.3	208.8	226.1
Gross Property Additions	3.2	13.2	9.9	33.2
Total Assets	1,899.7		1,899.7		1,633.9
Investments in Equity Method Investees	0.0		0.0		$ 0.0
G&M | Operating Segments | Nonrelated Party
Reportable Segment Information
Total Revenues	693.8	483.7	1,975.4	1,442.1
G&M | Operating Segments | Related Party
Reportable Segment Information
Total Revenues	$ 18.9	$ 15.4	$ 50.4	$ 88.0