CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - AEP Transmission Holdco - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024
Adjustments to Reconcile Net Income to Net Cash Flows from Operating Activities:
Depreciation and Amortization	$ 2,566.1	$ 2,461.7
Deferred Income Taxes	123.6	89.5
Allowance for Equity Funds Used During Construction	(172.9)	(153.0)
Property Taxes	541.3	508.3
Change in Other Noncurrent Assets	(719.7)	(244.0)
Change in Other Noncurrent Liabilities	133.8	193.8
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	(212.4)	(131.8)
Accounts Payable	327.3	14.2
Accrued Taxes, Net	(687.2)	(532.3)
Other Current Assets	37.7	(139.2)
Other Current Liabilities	74.3	161.8
Net Cash Flows from Operating Activities	5,130.8	5,076.9
INVESTING ACTIVITIES
Construction Expenditures	(6,001.2)	(5,168.6)
Other Investing Activities	43.5	73.0
Net Cash Flows Used for Investing Activities	(7,749.1)	(4,769.5)
FINANCING ACTIVITIES
Capital Contribution from Noncontrolling Interest	33.9	0.0
Issuance of Long-term Debt	6,249.2	3,748.5
Retirement of Long-term Debt	(2,803.8)	(1,969.1)
Proceeds from the Midwest Transmission Holdings Noncontrolling Interest Transaction, Net of Transaction Costs	2,782.9	0.0
Dividends Paid to Noncontrolling Interest	(71.5)	(4.7)
Net Cash Flows from (Used for) Financing Activities	3,479.1	(387.2)
Net Increase in Cash and Cash Equivalents	860.8	(79.8)
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	246.0	379.0
Cash, Cash Equivalents and Restricted Cash at End of Period	1,106.8	299.2
SUPPLEMENTARY INFORMATION
Cash Paid for Interest, Net of Capitalized Amounts	1,315.1	1,247.3
Net Cash Paid for Income Taxes	60.1	87.9
Construction Expenditures Included in Current Liabilities as of September 30,	1,168.8	1,015.1
AEPTCo
OPERATING ACTIVITIES
Net Income	1,033.5	548.2
Adjustments to Reconcile Net Income to Net Cash Flows from Operating Activities:
Depreciation and Amortization	354.3	320.8
Deferred Income Taxes	(145.4)	75.7
Allowance for Equity Funds Used During Construction	(64.7)	(64.7)
Property Taxes	213.4	196.3
Change in Other Noncurrent Assets	(61.1)	0.8
Change in Other Noncurrent Liabilities	(151.3)	(40.1)
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	(2.9)	5.4
Accounts Payable	17.9	(16.1)
Accrued Taxes, Net	(264.8)	(149.9)
Other Current Assets	5.5	(1.9)
Other Current Liabilities	3.4	22.2
Net Cash Flows from Operating Activities	937.8	896.7
INVESTING ACTIVITIES
Construction Expenditures	(1,144.7)	(1,042.9)
Change in Advances to Affiliates, Net	(37.2)	(114.7)
Other Investing Activities	21.3	13.6
Net Cash Flows Used for Investing Activities	(1,160.6)	(1,144.0)
FINANCING ACTIVITIES
Capital Contribution from AEP Member	42.9	34.6
Capital Contribution from Noncontrolling Interest	33.9	0.0
Return of Capital to AEP Member	0.0	(4.5)
Issuance of Long-term Debt	560.0	445.7
Retirement of Long-term Debt	(90.0)	0.0
Change in Advances from Affiliates, Net	24.2	(131.5)
Proceeds from the Midwest Transmission Holdings Noncontrolling Interest Transaction, Net of Transaction Costs	2,782.9	0.0
Dividends Paid to AEP Member	(3,062.6)	(97.0)
Dividends Paid to Noncontrolling Interest	(68.5)	0.0
Net Cash Flows from (Used for) Financing Activities	222.8	247.3
Net Increase in Cash and Cash Equivalents	0.0	0.0
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	0.0	0.0
Cash, Cash Equivalents and Restricted Cash at End of Period	0.0	0.0
SUPPLEMENTARY INFORMATION
Cash Paid for Interest, Net of Capitalized Amounts	139.8	128.0
Net Cash Paid for Income Taxes	115.4	5.7
Construction Expenditures Included in Current Liabilities as of September 30,	$ 222.5	$ 221.3