BUSINESS SEGMENTS - Schedule of AEPTCo's Reportable Segment Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Segment Reporting Information [Line Items]
Total Revenues	$ 5,463.4	$ 5,025.7
Other Operation and Maintenance	1,070.9	1,079.8
Depreciation and Amortization	833.4	787.1
Taxes Other Than Income Taxes	422.0	410.4
Allowance for Equity Funds Used During Construction	57.3	43.6
Interest Expense	494.9	435.6
Income Tax Expense (Benefit)	125.5	(141.9)
Gross Property Additions	2,100.2	1,761.7
Total Assets	104,394.6		$ 103,078.0
Operating Segments
Segment Reporting Information [Line Items]
Total Revenues	5,953.3	5,498.9
Other Operation and Maintenance	1,528.3	1,473.1
Depreciation and Amortization	838.4	792.4
Taxes Other Than Income Taxes	415.1	405.7
Allowance for Equity Funds Used During Construction	57.3	43.6
Interest Expense	371.1	316.3
Income Tax Expense (Benefit)	181.8	(95.3)
Gross Property Additions	2,058.8	1,753.6
Total Assets	102,478.8		101,506.6
Operating Segments | Nonrelated Party
Segment Reporting Information [Line Items]
Total Revenues	5,447.5	5,010.8
Corporate and Other
Segment Reporting Information [Line Items]
Total Revenues	44.6	52.8
Other Operation and Maintenance	15.8	36.1
Depreciation and Amortization	(5.1)	(5.3)
Taxes Other Than Income Taxes	0.5	0.1
Allowance for Equity Funds Used During Construction	0.0	0.0
Interest Expense	147.0	155.8
Income Tax Expense (Benefit)	(56.3)	(46.6)
Gross Property Additions	30.0	3.1
Total Assets	5,720.6		5,550.8
Corporate and Other | Nonrelated Party
Segment Reporting Information [Line Items]
Total Revenues	15.9	14.9
Reconciling Adjustments
Segment Reporting Information [Line Items]
Total Revenues	(534.5)	(526.0)
Other Operation and Maintenance	(473.2)	(429.4)
Depreciation and Amortization	0.1	0.0
Taxes Other Than Income Taxes	6.4	4.6
Allowance for Equity Funds Used During Construction	0.0	0.0
Interest Expense	(23.2)	(36.5)
Income Tax Expense (Benefit)	0.0	0.0
Gross Property Additions	11.4	5.0
Total Assets	(3,804.8)		(3,979.4)
Reconciling Adjustments | Nonrelated Party
Segment Reporting Information [Line Items]
Total Revenues	0.0	0.0
AEPTCo
Segment Reporting Information [Line Items]
Total Revenues	527.1	482.8
Other Revenues		2.4
Other Operation and Maintenance	34.4	35.2
Depreciation and Amortization	114.1	105.9
Taxes Other Than Income Taxes	74.1	73.4
Interest Income	0.4	1.9
Allowance for Equity Funds Used During Construction	22.4	17.9
Interest Expense	55.0	54.8
Income Tax Expense (Benefit)	60.8	52.1
NET INCOME	211.5	181.2
Gross Property Additions	421.8	336.5
Total Assets	16,702.8		16,370.3
AEPTCo | Nonrelated Party
Segment Reporting Information [Line Items]
Total Revenues	104.3	97.0
AEPTCo | Affiliated Entity
Segment Reporting Information [Line Items]
Total Revenues	422.8	383.4
AEPTCo | Operating Segments
Segment Reporting Information [Line Items]
Total Revenues	527.1	482.8
Other Operation and Maintenance	34.2	33.7
Taxes Other Than Income Taxes	74.1	73.4
AEPTCo | Corporate and Other
Segment Reporting Information [Line Items]
Total Revenues	0.0	0.0
Other Revenues		0.0
Other Operation and Maintenance	0.2	1.5
Depreciation and Amortization	0.0	0.0
Taxes Other Than Income Taxes	0.0	0.0
Interest Income	89.3	57.1
Allowance for Equity Funds Used During Construction	0.0	0.0
Interest Expense	60.0	56.3
Income Tax Expense (Benefit)	0.0	(0.2)
NET INCOME	29.1	(0.5)
Gross Property Additions	0.0	0.0
Total Assets	8,678.6		8,670.4
AEPTCo | Corporate and Other | Nonrelated Party
Segment Reporting Information [Line Items]
Total Revenues	0.0	0.0
AEPTCo | Corporate and Other | Affiliated Entity
Segment Reporting Information [Line Items]
Total Revenues	0.0	0.0
AEPTCo | Reconciling Adjustments
Segment Reporting Information [Line Items]
Total Revenues	0.0	0.0
Other Revenues		0.0
Other Operation and Maintenance	0.0	0.0
Depreciation and Amortization	0.0	0.0
Taxes Other Than Income Taxes	0.0	0.0
Interest Income	(89.0)	(56.2)
Allowance for Equity Funds Used During Construction	0.0	0.0
Interest Expense	(89.0)	(56.2)
Income Tax Expense (Benefit)	0.0	0.0
NET INCOME	0.0	0.0
Gross Property Additions	0.0	0.0
Total Assets	(8,684.6)		(9,187.8)
AEPTCo | Reconciling Adjustments | Nonrelated Party
Segment Reporting Information [Line Items]
Total Revenues	0.0	0.0
AEPTCo | Reconciling Adjustments | Affiliated Entity
Segment Reporting Information [Line Items]
Total Revenues	0.0	0.0
State Transcos [Member] | AEPTCo | Operating Segments
Segment Reporting Information [Line Items]
Other Revenues		2.4
Depreciation and Amortization	114.1	105.9
Interest Income	0.1	1.0
Allowance for Equity Funds Used During Construction	22.4	17.9
Interest Expense	84.0	54.7
Income Tax Expense (Benefit)	60.8	52.3
NET INCOME	182.4	181.7
Gross Property Additions	421.8	336.5
Total Assets	16,708.8		$ 16,887.7
State Transcos [Member] | AEPTCo | Operating Segments | Nonrelated Party
Segment Reporting Information [Line Items]
Total Revenues	104.3	97.0
State Transcos [Member] | AEPTCo | Operating Segments | Affiliated Entity
Segment Reporting Information [Line Items]
Total Revenues	$ 422.8	$ 383.4