SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF PARENT COMPANY - AEPTCO PARENT - CONDENSED STATEMENTS OF CASH FLOWS (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Adjustments to Reconcile Net Income to Net Cash Flows from Operating Activities:
Change in Other Noncurrent Assets	$ (347.6)	$ (465.1)	$ (187.7)
Change in Other Noncurrent Liabilities	306.3	29.0	337.8
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	(156.0)	236.5	(681.7)
Accounts Payable	85.1	(253.2)	489.2
Other Current Liabilities	182.6	(161.4)	54.3
Net Cash Flows from Operating Activities	6,804.3	5,012.2	5,288.0
INVESTING ACTIVITIES
Net Cash Flows Used for Investing Activities	(7,596.5)	(6,266.7)	(7,751.8)
FINANCING ACTIVITIES
Issuance of Long-term Debt	5,117.0	5,462.8	4,649.7
Retirement of Long-term Debt	(2,685.0)	(2,196.1)	(2,345.4)
Other Financing Activities	(49.8)	(78.6)	(105.4)
Net Cash Flows from Financing Activities	659.2	1,077.0	2,568.9
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	(133.0)	(177.5)	105.1
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	379.0	556.5	451.4
Cash, Cash Equivalents and Restricted Cash at End of Period	246.0	379.0	556.5
AEP TRANSMISSION COMPANY, LLC
OPERATING ACTIVITIES
Net Income	688.4	614.2	594.2
Adjustments to Reconcile Net Income to Net Cash Flows from Operating Activities:
Change in Other Noncurrent Assets	(0.6)	8.6	(7.4)
Change in Other Noncurrent Liabilities	(17.0)	134.2	68.7
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	13.4	(41.3)	(46.3)
Accounts Payable	9.5	22.8	18.5
Accrued Interest	5.3	10.8	0.0
Other Current Liabilities	13.3	(0.1)	3.0
Net Cash Flows from Operating Activities	1,237.8	1,137.6	995.3
INVESTING ACTIVITIES
Change in Advances to Affiliates, Net	36.7	(62.7)	22.8
Net Cash Flows Used for Investing Activities	(1,428.1)	(1,557.7)	(1,439.2)
FINANCING ACTIVITIES
Capital Contribution from Member	61.7	29.7	72.7
Return of Capital to Parent	(4.5)	(8.6)	0.0
Issuance of Long-term Debt	445.7	689.0	540.8
Retirement of Long-term Debt	(95.0)	(60.0)	(104.0)
Change in Advances from Affiliates, Net	(89.6)	(55.0)	104.4
Dividends Paid to Member	(128.0)	(175.0)	(170.0)
Net Cash Flows from Financing Activities	190.3	420.1	443.9
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	0.0	0.0	0.0
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	0.0	0.0	0.0
Cash, Cash Equivalents and Restricted Cash at End of Period	0.0	0.0	0.0
Parent Company
OPERATING ACTIVITIES
Net Income	2,967.1	2,208.1	2,307.2
Adjustments to Reconcile Net Income to Net Cash Flows from Operating Activities:
Equity Earnings of Unconsolidated Subsidiaries	(3,280.2)	(2,468.2)	(2,809.6)
Change in Other Noncurrent Assets	4.9	(28.4)	(5.0)
Change in Other Noncurrent Liabilities	70.8	92.3	83.5
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	17.9	28.7	(61.0)
Accounts Payable	(16.5)	(15.9)	1.1
Other Current Liabilities	55.3	(14.5)	(76.6)
Net Cash Flows from Operating Activities	888.6	528.5	337.9
INVESTING ACTIVITIES
Change in Advances to Affiliates, Net	59.9	2,007.6	(1,411.3)
Repayment of Notes Receivable from Affiliated Companies	(190.0)	0.0	0.0
Issuance of Notes Receivable to Affiliated Companies	0.0	210.0	20.0
Net Cash Flows Used for Investing Activities	748.3	1,063.5	(1,976.0)
FINANCING ACTIVITIES
Issuance of Long-term Debt	1,285.4	1,829.8	986.6
Retirement of Long-term Debt	(1,104.0)	(1,050.0)	(300.0)
Change in Advances from Affiliates, Net	(221.7)	(191.6)	336.9
Other Financing Activities	(41.1)	(59.6)	(74.5)
Net Cash Flows from Financing Activities	(1,747.2)	(1,648.4)	1,645.0
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	(110.3)	(56.4)	6.9
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	197.8	254.2	247.3
Cash, Cash Equivalents and Restricted Cash at End of Period	87.5	197.8	254.2
Parent Company | AEP TRANSMISSION COMPANY, LLC
OPERATING ACTIVITIES
Net Income	688.4	614.2	594.2
Adjustments to Reconcile Net Income to Net Cash Flows from Operating Activities:
Equity Earnings of Unconsolidated Subsidiaries	(687.8)	(612.9)	(594.2)
Change in Other Noncurrent Assets	0.0	3.8	0.0
Change in Other Noncurrent Liabilities	4.0	11.5	9.1
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	10.4	(37.5)	(2.2)
Accounts Payable	12.9	36.6	(0.6)
Accrued Interest	5.4	10.8	0.0
Other Current Liabilities	34.0	(30.5)	(0.8)
Net Cash Flows from Operating Activities	67.3	(4.0)	5.5
INVESTING ACTIVITIES
Change in Advances to Affiliates, Net	(20.4)	0.0	12.7
Repayment of Notes Receivable from Affiliated Companies	95.0	60.0	104.0
Issuance of Notes Receivable to Affiliated Companies	450.0	700.0	550.0
Return of Capital Contributions from Unconsolidated Subsidiaries	132.8	183.7	130.0
Capital Contributions to Subsidiaries	(61.7)	(29.7)	(69.5)
Net Cash Flows Used for Investing Activities	(304.3)	(486.0)	(372.8)
FINANCING ACTIVITIES
Capital Contribution from Member	61.7	29.7	72.7
Return of Capital to Parent	(4.5)	(8.6)	0.0
Issuance of Long-term Debt	445.7	689.0	540.8
Retirement of Long-term Debt	(95.0)	(60.0)	(104.0)
Change in Advances from Affiliates, Net	(42.7)	14.9	27.8
Dividends Paid to Member	(128.0)	(175.0)	(170.0)
Other Financing Activities	(0.2)	0.0	0.0
Net Cash Flows from Financing Activities	237.0	490.0	367.3
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	0.0	0.0	0.0
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	0.0	0.0	0.0
Cash, Cash Equivalents and Restricted Cash at End of Period	$ 0.0	$ 0.0	$ 0.0