Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Operating Activities
Net Income (Loss)	$ 1,152.6	$ 1,013.8
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	1,403.6	1,351.7
Rockport Plant, Unit 2 Operating Lease Amortization	66.8	68.3
Deferred Income Taxes	86.7	60.0
Allowance for Equity Funds Used During Construction	(66.9)	(66.5)
Mark-to-Market of Risk Management Contracts	26.1	13.7
Amortization of Nuclear Fuel	40.4	45.6
Property Taxes	167.3	173.6
Deferred Fuel Over/Under-Recovery, Net	(1,218.2)	76.0
Change in Other Noncurrent Assets	(291.9)	(143.9)
Change in Other Noncurrent Liabilities	163.5	(50.0)
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	(215.5)	(80.7)
Fuel, Materials and Supplies	132.3	(120.3)
Accounts Payable	97.5	(64.7)
Accrued Taxes, Net	(237.4)	(164.4)
Rockport Plant, Unit 2 Operating Lease	(73.9)	(73.9)
Other Current Assets	10.4	18.8
Other Current Liabilities	(199.5)	(310.9)
Net Cash Flows from (Used for) Operating Activities	1,043.9	1,746.2
Investing Activities
Construction Expenditures	(2,784.8)	(3,244.9)
Purchases of Investment Securities	(1,162.8)	(988.4)
Sales of Investment Securities	1,131.8	971.3
Acquisitions of Nuclear Fuel	(63.0)	(37.7)
Other Investing Activities	33.3	52.1
Net Cash Flows from (Used for) Investing Activities	(3,229.8)	(3,247.6)
Financing Activities
Issuance of Common Stock	256.9	111.0
Issuance of Long-term Debt	3,055.1	2,431.3
Issuance of Short-term Debt with Original Maturities greater than 90 Days	1,178.5	1,304.5
Change in Short-term Debt with Original Maturities less than 90 Days, Net	(437.8)	(766.2)
Retirement of Long-term Debt	(998.1)	(433.2)
Redemption of Short-term Debt with Original Maturities Greater than 90 Days	(92.0)	(300.0)
Principal Payments for Finance Leases Obligations	(30.3)	(31.3)
Dividends Paid on Common Stock	(746.5)	(704.6)
Other Financing Activities	(78.5)	(38.0)
Net Cash Flows from (Used for) Financing Activities	2,107.3	1,573.5
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	(78.6)	72.1
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	438.3	432.6
Cash and Cash Equivalents at Beginning of Period	392.7
Cash, Cash Equivalents and Restricted Cash at End of Period	359.7	504.7
Cash and Cash Equivalents at End of Period	312.7
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	559.9	481.2
Net Cash Paid (Received) for Income Taxes	8.6	3.1
Noncash Acquisitions Under Finance Leases	16.3	26.8
Construction Expenditures Included in Current Liabilities as of June 30,	789.3	833.3
Construction Expenditures Included in Noncurrent Liabilities as of June 30,	0.0	8.3
Acquisition of Nuclear Fuel Included in Current Liabilities as of June 30,	0.0	22.3
Expected Reimbursement for Spent Nuclear Fuel Dry Cask Storage	0.2	2.2
Dry Lake Solar Project
Investing Activities
Acquisitions of Assets	(114.3)	0.0
North Central Wind Energy Facilities
Investing Activities
Acquisitions of Assets	(270.0)	0.0
AEP Texas Inc. [Member]
Operating Activities
Net Income (Loss)	125.9	114.5
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	199.5	328.1
Deferred Income Taxes	14.0	(33.9)
Allowance for Equity Funds Used During Construction	(7.5)	(10.0)
Mark-to-Market of Risk Management Contracts	0.0	0.1
Property Taxes	(49.7)	(43.2)
Change in Other Noncurrent Assets	(42.0)	(54.1)
Change in Other Noncurrent Liabilities	17.2	(2.5)
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	(43.8)	(54.1)
Fuel, Materials and Supplies	0.5	(11.4)
Accounts Payable	(10.3)	22.1
Accrued Taxes, Net	47.4	79.3
Other Current Assets	0.7	1.6
Other Current Liabilities	(29.3)	(38.7)
Net Cash Flows from (Used for) Operating Activities	222.6	297.8
Investing Activities
Construction Expenditures	(531.2)	(662.0)
Change in Advances to Affiliates, Net	(47.2)	200.0
Other Investing Activities	21.3	17.1
Net Cash Flows from (Used for) Investing Activities	(557.1)	(444.9)
Financing Activities
Issuance of Long-term Debt	444.3	0.0
Change in Short-term Debt with Original Maturities less than 90 Days, Net	0.0	2.0
Change in Advances from Affiliates, Net	(67.1)	320.4
Retirement of Long-term Debt	(40.9)	(193.8)
Principal Payments for Finance Leases Obligations	(3.3)	(3.1)
Other Financing Activities	0.7	0.5
Net Cash Flows from (Used for) Financing Activities	333.7	126.0
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	(0.8)	(21.1)
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	28.8	157.8
Cash and Cash Equivalents at Beginning of Period	0.1
Cash, Cash Equivalents and Restricted Cash at End of Period	28.0	136.7
Cash and Cash Equivalents at End of Period	0.1
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	82.0	74.3
Net Cash Paid (Received) for Income Taxes	(9.2)	(24.9)
Noncash Acquisitions Under Finance Leases	2.4	4.3
Construction Expenditures Included in Current Liabilities as of June 30,	125.5	192.3
AEP Transmission Co [Member]
Operating Activities
Net Income (Loss)	300.3	191.5
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	143.0	114.9
Deferred Income Taxes	55.5	22.6
Allowance for Equity Funds Used During Construction	(33.3)	(34.7)
Property Taxes	93.3	84.3
Change in Other Noncurrent Assets	(4.5)	(2.6)
Change in Other Noncurrent Liabilities	10.5	30.6
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	(22.2)	(74.7)
Fuel, Materials and Supplies	(0.5)	0.4
Accounts Payable	0.1	10.5
Accrued Taxes, Net	(106.2)	(54.7)
Other Current Assets	0.7	0.5
Other Current Liabilities	(1.5)	4.5
Net Cash Flows from (Used for) Operating Activities	435.2	293.1
Investing Activities
Construction Expenditures	(719.7)	(825.4)
Change in Advances to Affiliates, Net	(4.5)	(35.9)
Other Investing Activities	(3.4)	1.8
Net Cash Flows from (Used for) Investing Activities	(727.6)	(859.5)
Financing Activities
Capital Contributions from Parent	184.0	185.0
Issuance of Long-term Debt	0.0	519.4
Change in Advances from Affiliates, Net	108.6	(133.0)
Dividends Paid on Common Stock	0.0	(5.0)
Other Financing Activities	(0.2)	0.0
Net Cash Flows from (Used for) Financing Activities	292.4	566.4
Net Increase (Decrease) in Cash and Cash Equivalents	0.0	0.0
Cash and Cash Equivalents at Beginning of Period	0.0	0.0
Cash and Cash Equivalents at End of Period	0.0	0.0
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	66.6	55.8
Net Cash Paid (Received) for Income Taxes	21.6	13.5
Construction Expenditures Included in Current Liabilities as of June 30,	267.9	263.8
Appalachian Power Co [Member]
Operating Activities
Net Income (Loss)	188.8	196.6
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	271.2	242.8
Deferred Income Taxes	4.0	(11.8)
Allowance for Equity Funds Used During Construction	(7.8)	(4.8)
Mark-to-Market of Risk Management Contracts	(16.8)	1.5
Deferred Fuel Over/Under-Recovery, Net	(21.1)	30.9
Change in Other Noncurrent Assets	(70.2)	(11.1)
Change in Other Noncurrent Liabilities	12.5	(21.3)
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	23.7	(37.3)
Fuel, Materials and Supplies	45.4	(2.2)
Accounts Payable	(3.9)	(69.6)
Accrued Taxes, Net	(26.6)	8.9
Other Current Assets	(8.8)	18.8
Other Current Liabilities	(23.0)	(29.7)
Net Cash Flows from (Used for) Operating Activities	367.4	311.7
Investing Activities
Construction Expenditures	(374.8)	(400.2)
Change in Advances to Affiliates, Net	(70.3)	(60.2)
Other Investing Activities	11.1	3.9
Net Cash Flows from (Used for) Investing Activities	(434.0)	(456.5)
Financing Activities
Issuance of Long-term Debt	494.0	492.2
Change in Advances from Affiliates, Net	(18.6)	(236.7)
Retirement of Long-term Debt	(380.0)	(12.2)
Principal Payments for Finance Leases Obligations	(3.9)	(3.6)
Dividends Paid on Common Stock	(25.0)	(100.0)
Other Financing Activities	0.4	0.1
Net Cash Flows from (Used for) Financing Activities	66.9	139.8
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	0.3	(5.0)
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	22.7	26.8
Cash and Cash Equivalents at Beginning of Period	5.8
Cash, Cash Equivalents and Restricted Cash at End of Period	23.0	21.8
Cash and Cash Equivalents at End of Period	3.9
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	104.7	101.8
Net Cash Paid (Received) for Income Taxes	35.8	7.4
Noncash Acquisitions Under Finance Leases	0.9	2.2
Construction Expenditures Included in Current Liabilities as of June 30,	98.0	97.3
Indiana Michigan Power Co [Member]
Operating Activities
Net Income (Loss)	128.0	156.1
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	218.1	199.1
Rockport Plant, Unit 2 Operating Lease Amortization	33.9	34.6
Deferred Income Taxes	(8.2)	(47.1)
Amortization (Deferral) of Incremental Nuclear Refueling Outage Expenses, Net	(14.3)	28.4
Allowance for Equity Funds Used During Construction	(7.0)	(4.8)
Mark-to-Market of Risk Management Contracts	(3.1)	3.2
Amortization of Nuclear Fuel	40.4	45.6
Deferred Fuel Over/Under-Recovery, Net	(5.7)	26.9
Change in Other Noncurrent Assets	11.7	16.1
Change in Other Noncurrent Liabilities	26.2	33.2
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	(0.4)	(18.1)
Fuel, Materials and Supplies	27.1	(26.9)
Accounts Payable	16.4	(33.7)
Accrued Taxes, Net	(5.3)	2.7
Operating Lease, Payments	(36.9)	(36.9)
Other Current Assets	2.0	9.7
Other Current Liabilities	(29.1)	(44.5)
Net Cash Flows from (Used for) Operating Activities	393.8	343.6
Investing Activities
Construction Expenditures	(241.0)	(267.6)
Change in Advances to Affiliates, Net	(86.6)	(0.1)
Purchases of Investment Securities	(1,149.7)	(971.4)
Sales of Investment Securities	1,122.7	940.5
Acquisitions of Nuclear Fuel	(63.0)	(37.7)
Other Investing Activities	4.5	6.2
Net Cash Flows from (Used for) Investing Activities	(413.1)	(330.1)
Financing Activities
Issuance of Long-term Debt	507.0	0.0
Change in Advances from Affiliates, Net	(103.0)	79.7
Retirement of Long-term Debt	(282.7)	(47.6)
Principal Payments for Finance Leases Obligations	(3.3)	(3.3)
Dividends Paid on Common Stock	(100.0)	(42.5)
Other Financing Activities	0.5	0.2
Net Cash Flows from (Used for) Financing Activities	18.5	(13.5)
Net Increase (Decrease) in Cash and Cash Equivalents	(0.8)	0.0
Cash and Cash Equivalents at Beginning of Period	3.3	2.0
Cash and Cash Equivalents at End of Period	2.5	2.0
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	52.1	55.6
Net Cash Paid (Received) for Income Taxes	4.1	48.0
Noncash Acquisitions Under Finance Leases	2.8	1.6
Construction Expenditures Included in Current Liabilities as of June 30,	59.9	69.9
Acquisition of Nuclear Fuel Included in Current Liabilities as of June 30,	0.0	22.3
Expected Reimbursement for Spent Nuclear Fuel Dry Cask Storage	0.2	2.2
Ohio Power Co [Member]
Operating Activities
Net Income (Loss)	142.2	156.0
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	151.7	130.3
Deferred Income Taxes	21.5	21.6
Carrying Costs Income	(1.0)	(1.0)
Allowance for Equity Funds Used During Construction	(5.6)	(4.7)
Mark-to-Market of Risk Management Contracts	(4.8)	13.9
Property Taxes	154.2	151.4
Change in Other Noncurrent Assets	(45.8)	(103.2)
Change in Other Noncurrent Liabilities	7.2	(45.4)
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	(47.9)	(14.1)
Fuel, Materials and Supplies	(3.0)	(16.8)
Accounts Payable	(13.6)	(23.1)
Accrued Taxes, Net	(222.8)	(150.8)
Other Current Assets	0.8	3.1
Other Current Liabilities	13.9	(25.7)
Net Cash Flows from (Used for) Operating Activities	148.0	92.5
Investing Activities
Construction Expenditures	(353.3)	(416.7)
Other Investing Activities	6.6	10.3
Net Cash Flows from (Used for) Investing Activities	(346.7)	(406.4)
Financing Activities
Issuance of Long-term Debt	445.8	347.0
Change in Advances from Affiliates, Net	(202.9)	12.1
Retirement of Long-term Debt	(0.1)	0.0
Principal Payments for Finance Leases Obligations	(2.4)	(2.4)
Dividends Paid on Common Stock	(43.8)	(43.8)
Other Financing Activities	0.5	0.6
Net Cash Flows from (Used for) Financing Activities	197.1	313.5
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	(1.6)	(0.4)
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	7.4	3.7
Cash and Cash Equivalents at Beginning of Period	7.4
Cash, Cash Equivalents and Restricted Cash at End of Period	5.8	3.3
Cash and Cash Equivalents at End of Period	5.8
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	58.4	54.1
Net Cash Paid (Received) for Income Taxes	1.3	2.4
Noncash Acquisitions Under Finance Leases	0.9	4.9
Construction Expenditures Included in Current Liabilities as of June 30,	70.9	74.1
Public Service Co Of Oklahoma [Member]
Operating Activities
Net Income (Loss)	43.4	36.1
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	100.1	89.7
Deferred Income Taxes	25.7	(9.2)
Allowance for Equity Funds Used During Construction	(1.0)	(1.9)
Mark-to-Market of Risk Management Contracts	(12.7)	(7.9)
Property Taxes	(21.8)	(21.2)
Deferred Fuel Over/Under-Recovery, Net	(724.1)	(17.1)
Change in Other Noncurrent Assets	(16.6)	(4.8)
Change in Other Noncurrent Liabilities	0.4	1.3
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	(22.1)	(24.3)
Fuel, Materials and Supplies	8.5	(18.1)
Accounts Payable	11.7	(1.5)
Accrued Taxes, Net	59.2	38.5
Other Current Assets	(4.4)	1.8
Other Current Liabilities	(22.0)	(10.0)
Net Cash Flows from (Used for) Operating Activities	(575.7)	51.4
Investing Activities
Construction Expenditures	(145.9)	(184.8)
Change in Advances to Affiliates, Net	0.0	38.8
Acquisitions of Assets	122.8	0.0
Other Investing Activities	1.3	2.0
Net Cash Flows from (Used for) Investing Activities	(267.4)	(144.0)
Financing Activities
Capital Contributions from Parent	625.0	0.0
Issuance of Long-term Debt	500.0	0.0
Change in Advances from Affiliates, Net	(20.3)	106.9
Retirement of Long-term Debt	(250.3)	(12.9)
Principal Payments for Finance Leases Obligations	(1.7)	(1.8)
Dividends Paid on Common Stock	(10.0)	0.0
Other Financing Activities	0.4	0.3
Net Cash Flows from (Used for) Financing Activities	843.1	92.5
Net Increase (Decrease) in Cash and Cash Equivalents	0.0	(0.1)
Cash and Cash Equivalents at Beginning of Period	2.6	1.5
Cash and Cash Equivalents at End of Period	2.6	1.4
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	32.2	30.6
Net Cash Paid (Received) for Income Taxes	(65.0)	(2.7)
Noncash Acquisitions Under Finance Leases	2.3	2.6
Construction Expenditures Included in Current Liabilities as of June 30,	27.9	25.3
Southwestern Electric Power Co [Member]
Operating Activities
Net Income (Loss)	100.8	75.3
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	142.6	135.4
Deferred Income Taxes	8.1	(12.4)
Allowance for Equity Funds Used During Construction	(4.0)	(2.3)
Mark-to-Market of Risk Management Contracts	(13.1)	(1.8)
Property Taxes	(41.7)	(33.0)
Deferred Fuel Over/Under-Recovery, Net	(470.6)	31.1
Change in Regulatory Assets	(50.6)	(4.3)
Change in Other Noncurrent Assets	17.3	2.7
Change in Other Noncurrent Liabilities	34.1	13.5
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	(82.0)	(5.8)
Fuel, Materials and Supplies	29.1	(60.4)
Accounts Payable	(5.2)	2.9
Accrued Taxes, Net	82.7	52.0
Other Current Assets	9.8	0.2
Other Current Liabilities	(37.9)	(32.6)
Net Cash Flows from (Used for) Operating Activities	(280.6)	160.5
Investing Activities
Construction Expenditures	(182.5)	(228.5)
Change in Advances to Affiliates, Net	(27.6)	0.0
Acquisitions of Assets	147.1	0.0
Other Investing Activities	1.0	4.3
Net Cash Flows from (Used for) Investing Activities	(356.2)	(224.2)
Financing Activities
Capital Contributions from Parent	175.0	0.0
Issuance of Long-term Debt	496.4	0.0
Change in Short-term Debt with Original Maturities less than 90 Days, Net	(35.0)	18.7
Change in Advances from Affiliates, Net	25.0	70.5
Retirement of Long-term Debt	(3.1)	(18.1)
Principal Payments for Finance Leases Obligations	(5.4)	(5.5)
Dividends Paid on Common Stock	(1.6)	(1.9)
Other Financing Activities	0.3	0.2
Net Cash Flows from (Used for) Financing Activities	651.6	63.9
Net Increase (Decrease) in Cash and Cash Equivalents	14.8	0.2
Cash and Cash Equivalents at Beginning of Period	13.2	1.6
Cash and Cash Equivalents at End of Period	28.0	1.8
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	55.6	57.0
Net Cash Paid (Received) for Income Taxes	(12.8)	8.1
Noncash Acquisitions Under Finance Leases	3.2	4.3
Construction Expenditures Included in Current Liabilities as of June 30,	41.9	33.7
Noncontrolling Interest [Member]
Supplementary Information
Noncash or Part Noncash Acquisition, Investments Acquired	$ 33.4	$ 0.0