Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Operating Activities
Net Income (Loss)	$ 1,013.8	$ 1,033.2
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	1,351.7	1,228.4
Deferred Income Taxes	60.0	(35.5)
Allowance for Equity Funds Used During Construction	(66.5)	(79.3)
Mark-to-Market of Risk Management Contracts	13.7	(72.9)
Amortization of Nuclear Fuel	45.6	46.1
Property Taxes	173.6	137.6
Deferred Fuel Over/Under-Recovery, Net	76.0	36.7
Recovery of Ohio Capacity Costs, Net	0.0	29.0
Refund of Global Settlement	0.0	(8.2)
Change in Other Noncurrent Assets	(75.6)	(73.5)
Change in Other Noncurrent Liabilities	(50.0)	(53.6)
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	(80.7)	165.5
Fuel, Materials and Supplies	(120.3)	(114.6)
Accounts Payable	(64.7)	(72.4)
Accrued Taxes, Net	(164.4)	(170.1)
Other Current Assets	18.8	27.4
Other Current Liabilities	(384.8)	(223.0)
Net Cash Flows from (Used for) Operating Activities	1,746.2	1,800.8
Investing Activities
Construction Expenditures	(3,244.9)	(2,986.7)
Purchases of Investment Securities	(988.4)	(235.5)
Sales of Investment Securities	971.3	199.5
Acquisitions of Nuclear Fuel	(37.7)	(33.8)
Acquisitions of Assets	0.0	(581.2)
Other Investing Activities	52.1	42.7
Net Cash Flows from (Used for) Investing Activities	(3,247.6)	(3,595.0)
Financing Activities
Issuance of Common Stock, Net	111.0	32.3
Issuance of Long-term Debt	2,431.3	2,773.7
Issuance of Short-term Debt with Original Maturities greater than 90 Days	1,304.5	0.0
Change in Short-term Debt, Net	(766.2)	367.0
Retirement of Long-term Debt	(433.2)	(728.2)
Make Whole Premium on Extinguishment of Long-term Debt	0.0	(3.0)
Repayments of Short-term Debt, Maturing in More than Three Months	(300.0)	0.0
Principal Payments for Finance Leases	(31.3)	(29.6)
Dividends Paid on Common Stock	(704.6)	(668.1)
Other Financing Activities	(38.0)	(4.3)
Net Cash Flows from (Used for) Financing Activities	1,573.5	1,739.8
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	72.1	(54.4)
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	432.6	444.1
Cash and Cash Equivalents at Beginning of Period	246.8
Cash, Cash Equivalents and Restricted Cash at End of Period	504.7	389.7
Cash and Cash Equivalents at End of Period	348.8
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	481.2	490.2
Net Cash Paid (Received) for Income Taxes	3.1	19.7
Noncash Acquisitions Under Finance Leases	26.8	44.4
Construction Expenditures Included in Current Liabilities as of June 30,	833.3	904.8
Construction Expenditures Included in Noncurrent Liabilities as of June 30,	8.3	0.0
Acquisition of Nuclear Fuel Included in Current Liabilities as of June 30,	22.3	50.5
Expected Reimbursement for Spent Nuclear Fuel Dry Cask Storage	2.2	0.0
Noncash or Part Noncash Acquisition, Value of Liabilities Assumed	0.0	18.6
AEP Texas Inc. [Member]
Operating Activities
Net Income (Loss)	114.5	115.0
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	328.1	294.6
Deferred Income Taxes	(33.9)	(59.9)
Allowance for Equity Funds Used During Construction	(10.0)	(3.2)
Mark-to-Market of Risk Management Contracts	0.1	0.0
Property Taxes	(43.2)	(45.0)
Change in Other Noncurrent Assets	(54.1)	24.4
Change in Other Noncurrent Liabilities	(2.5)	5.6
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	(54.1)	(46.2)
Fuel, Materials and Supplies	(11.4)	0.8
Accounts Payable	22.1	1.8
Accrued Taxes, Net	79.3	26.4
Other Current Assets	1.6	2.0
Other Current Liabilities	(38.7)	(21.8)
Net Cash Flows from (Used for) Operating Activities	297.8	294.5
Investing Activities
Construction Expenditures	(662.0)	(671.6)
Change in Advances to Affiliates, Net	200.0	0.3
Other Investing Activities	17.1	7.6
Net Cash Flows from (Used for) Investing Activities	(444.9)	(663.7)
Financing Activities
Capital Contributions from Parent	0.0	200.0
Issuance of Long-term Debt	0.0	295.6
Change in Short-term Debt, Net	2.0	0.0
Change in Advances from Affiliates, Net	320.4	23.0
Retirement of Long-term Debt	(193.8)	(181.8)
Principal Payments for Finance Leases	(3.1)	(2.5)
Other Financing Activities	0.5	0.6
Net Cash Flows from (Used for) Financing Activities	126.0	334.9
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	(21.1)	(34.3)
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	157.8	159.8
Cash and Cash Equivalents at Beginning of Period	3.1
Cash, Cash Equivalents and Restricted Cash at End of Period	136.7	125.5
Cash and Cash Equivalents at End of Period	0.1
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	74.3	73.4
Net Cash Paid (Received) for Income Taxes	(24.9)	14.4
Noncash Acquisitions Under Finance Leases	4.3	4.4
Construction Expenditures Included in Current Liabilities as of June 30,	192.3	192.9
AEP Transmission Co [Member]
Operating Activities
Net Income (Loss)	191.5	240.3
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	114.9	83.1
Deferred Income Taxes	22.6	19.7
Allowance for Equity Funds Used During Construction	(34.7)	(40.1)
Property Taxes	84.3	68.3
Long-term Accounts Receivable - Affiliated	0.0	(7.8)
Change in Other Noncurrent Assets	(2.6)	3.6
Change in Other Noncurrent Liabilities	30.6	(6.4)
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	(74.7)	(31.7)
Fuel, Materials and Supplies	0.4	1.8
Accounts Payable	10.5	6.3
Accrued Taxes, Net	(54.7)	(43.1)
Accrued Interest	4.7	0.4
Other Current Assets	0.5	0.0
Other Current Liabilities	(0.2)	(0.2)
Net Cash Flows from (Used for) Operating Activities	293.1	294.2
Investing Activities
Construction Expenditures	(825.4)	(661.5)
Change in Advances to Affiliates, Net	(35.9)	45.7
Acquisitions of Assets	(2.4)	(2.6)
Other Investing Activities	4.2	4.8
Net Cash Flows from (Used for) Investing Activities	(859.5)	(613.6)
Financing Activities
Capital Contributions from Parent	185.0	0.0
Issuance of Long-term Debt	519.4	344.3
Change in Advances from Affiliates, Net	(133.0)	(24.9)
Dividends Paid on Common Stock	(5.0)	0.0
Net Cash Flows from (Used for) Financing Activities	566.4	319.4
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	55.8	41.0
Net Cash Paid (Received) for Income Taxes	13.5	17.4
Construction Expenditures Included in Current Liabilities as of June 30,	263.8	278.5
Appalachian Power Co [Member]
Operating Activities
Net Income (Loss)	196.6	189.2
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	242.8	229.6
Deferred Income Taxes	(11.8)	(73.5)
Allowance for Equity Funds Used During Construction	(4.8)	(7.7)
Mark-to-Market of Risk Management Contracts	1.5	(12.9)
Deferred Fuel Over/Under-Recovery, Net	30.9	41.4
Change in Other Noncurrent Assets	(11.1)	(1.8)
Change in Other Noncurrent Liabilities	(21.3)	(31.2)
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	(37.3)	60.2
Fuel, Materials and Supplies	(2.2)	(50.2)
Accounts Payable	(69.6)	23.0
Accrued Taxes, Net	8.9	(7.8)
Other Current Assets	18.8	17.4
Other Current Liabilities	(29.7)	(29.8)
Net Cash Flows from (Used for) Operating Activities	311.7	345.9
Investing Activities
Construction Expenditures	(400.2)	(397.1)
Change in Advances to Affiliates, Net	(60.2)	0.3
Other Investing Activities	3.9	20.7
Net Cash Flows from (Used for) Investing Activities	(456.5)	(376.1)
Financing Activities
Issuance of Long-term Debt	492.2	478.3
Change in Advances from Affiliates, Net	(236.7)	(179.5)
Retirement of Long-term Debt	(12.2)	(168.0)
Principal Payments for Finance Leases	(3.6)	(3.1)
Dividends Paid on Common Stock	(100.0)	(100.0)
Other Financing Activities	0.1	0.4
Net Cash Flows from (Used for) Financing Activities	139.8	28.1
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	(5.0)	(2.1)
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	26.8	29.8
Cash and Cash Equivalents at Beginning of Period	3.3
Cash, Cash Equivalents and Restricted Cash at End of Period	21.8	27.7
Cash and Cash Equivalents at End of Period	2.5
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	101.8	91.6
Net Cash Paid (Received) for Income Taxes	7.4	35.0
Noncash Acquisitions Under Finance Leases	2.2	5.7
Construction Expenditures Included in Current Liabilities as of June 30,	97.3	116.5
Indiana Michigan Power Co [Member]
Operating Activities
Net Income (Loss)	156.1	159.2
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	199.1	173.5
Deferred Income Taxes	(47.1)	(17.2)
Deferral of Incremental Nuclear Refueling Outage Expenses, Net	28.4	(14.3)
Allowance for Equity Funds Used During Construction	(4.8)	(12.5)
Mark-to-Market of Risk Management Contracts	3.2	(6.0)
Amortization of Nuclear Fuel	45.6	46.1
Deferred Fuel Over/Under-Recovery, Net	26.9	(16.5)
Change in Other Noncurrent Assets	50.7	34.0
Change in Other Noncurrent Liabilities	33.2	(3.6)
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	(18.1)	35.8
Fuel, Materials and Supplies	(26.9)	(3.8)
Accounts Payable	(33.7)	(50.4)
Accrued Taxes, Net	2.7	(15.9)
Other Current Assets	9.7	9.6
Other Current Liabilities	(81.4)	(38.6)
Net Cash Flows from (Used for) Operating Activities	343.6	279.4
Investing Activities
Construction Expenditures	(267.6)	(293.8)
Change in Advances to Affiliates, Net	(0.1)	(0.3)
Purchases of Investment Securities	(971.4)	(226.6)
Sales of Investment Securities	940.5	199.5
Acquisitions of Nuclear Fuel	(37.7)	(33.8)
Other Investing Activities	6.2	9.0
Net Cash Flows from (Used for) Investing Activities	(330.1)	(346.0)
Financing Activities
Issuance of Long-term Debt	0.0	62.8
Change in Advances from Affiliates, Net	79.7	93.6
Retirement of Long-term Debt	(47.6)	(48.3)
Principal Payments for Finance Leases	(3.3)	(2.7)
Dividends Paid on Common Stock	(42.5)	(40.0)
Other Financing Activities	0.2	0.2
Net Cash Flows from (Used for) Financing Activities	(13.5)	65.6
Net Increase (Decrease) in Cash and Cash Equivalents	0.0	(1.0)
Cash and Cash Equivalents at Beginning of Period	2.0	2.4
Cash and Cash Equivalents at End of Period	2.0	1.4
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	55.6	55.2
Net Cash Paid (Received) for Income Taxes	48.0	27.9
Noncash Acquisitions Under Finance Leases	1.6	4.5
Construction Expenditures Included in Current Liabilities as of June 30,	69.9	77.7
Acquisition of Nuclear Fuel Included in Current Liabilities as of June 30,	22.3	50.5
Expected Reimbursement for Spent Nuclear Fuel Dry Cask Storage	2.2	0.0
Ohio Power Co [Member]
Operating Activities
Net Income (Loss)	156.0	178.6
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	130.3	119.4
Amortization Of Generation Deferrals	0.0	56.5
Deferred Income Taxes	21.6	9.4
Carrying Costs Income	(1.0)	(0.4)
Allowance for Equity Funds Used During Construction	(4.7)	(9.3)
Mark-to-Market of Risk Management Contracts	13.9	12.1
Property Taxes	151.4	130.1
Refund of Global Settlement	0.0	(8.2)
Reversal of a Regulatory Provision	0.0	(56.2)
Change in Other Noncurrent Assets	(103.2)	(30.5)
Change in Other Noncurrent Liabilities	(45.4)	(38.0)
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	(14.1)	70.0
Fuel, Materials and Supplies	(16.8)	(8.5)
Accounts Payable	(23.1)	(34.9)
Accrued Taxes, Net	(150.8)	(169.4)
Other Current Assets	3.1	(4.2)
Other Current Liabilities	(25.7)	2.6
Net Cash Flows from (Used for) Operating Activities	92.5	219.5
Investing Activities
Construction Expenditures	(416.7)	(385.5)
Change in Advances to Affiliates, Net	0.0	(63.9)
Other Investing Activities	10.3	7.5
Net Cash Flows from (Used for) Investing Activities	(406.4)	(441.9)
Financing Activities
Issuance of Long-term Debt	347.0	444.3
Change in Advances from Affiliates, Net	12.1	(114.1)
Retirement of Long-term Debt	0.0	(23.4)
Principal Payments for Finance Leases	(2.4)	(1.8)
Dividends Paid on Common Stock	(43.8)	(85.0)
Other Financing Activities	0.6	0.8
Net Cash Flows from (Used for) Financing Activities	313.5	220.8
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	(0.4)	(1.6)
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	3.7	32.5
Cash and Cash Equivalents at Beginning of Period	3.7
Cash, Cash Equivalents and Restricted Cash at End of Period	3.3	30.9
Cash and Cash Equivalents at End of Period	3.3
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	54.1	46.1
Net Cash Paid (Received) for Income Taxes	2.4	14.3
Noncash Acquisitions Under Finance Leases	4.9	6.1
Construction Expenditures Included in Current Liabilities as of June 30,	74.1	77.9
Public Service Co Of Oklahoma [Member]
Operating Activities
Net Income (Loss)	36.1	48.1
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	89.7	86.3
Deferred Income Taxes	(9.2)	(9.0)
Allowance for Equity Funds Used During Construction	(1.9)	(0.7)
Mark-to-Market of Risk Management Contracts	(7.9)	(18.3)
Property Taxes	(21.2)	(19.2)
Deferred Fuel Over/Under-Recovery, Net	(17.1)	9.0
Change in Other Noncurrent Assets	(4.8)	4.6
Change in Other Noncurrent Liabilities	1.3	(2.4)
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	(24.3)	(12.6)
Fuel, Materials and Supplies	(18.1)	0.4
Accounts Payable	(1.5)	28.5
Accrued Taxes, Net	38.5	12.8
Other Current Assets	1.8	(1.6)
Other Current Liabilities	(10.0)	3.3
Net Cash Flows from (Used for) Operating Activities	51.4	129.2
Investing Activities
Construction Expenditures	(184.8)	(132.7)
Change in Advances to Affiliates, Net	38.8	0.0
Other Investing Activities	2.0	1.1
Net Cash Flows from (Used for) Investing Activities	(144.0)	(131.6)
Financing Activities
Issuance of Long-term Debt	0.0	349.9
Change in Advances from Affiliates, Net	106.9	(82.9)
Retirement of Long-term Debt	(12.9)	(250.2)
Principal Payments for Finance Leases	(1.8)	(1.5)
Dividends Paid on Common Stock	0.0	(11.3)
Other Financing Activities	0.3	(2.2)
Net Cash Flows from (Used for) Financing Activities	92.5	1.8
Net Increase (Decrease) in Cash and Cash Equivalents	(0.1)	(0.6)
Cash and Cash Equivalents at Beginning of Period	1.5	2.0
Cash and Cash Equivalents at End of Period	1.4	1.4
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	30.6	30.9
Net Cash Paid (Received) for Income Taxes	(2.7)	11.1
Noncash Acquisitions Under Finance Leases	2.6	2.3
Construction Expenditures Included in Current Liabilities as of June 30,	25.3	19.7
Southwestern Electric Power Co [Member]
Operating Activities
Net Income (Loss)	75.3	36.3
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	135.4	123.9
Deferred Income Taxes	(12.4)	(10.1)
Allowance for Equity Funds Used During Construction	(2.3)	(2.9)
Mark-to-Market of Risk Management Contracts	(1.8)	(6.2)
Property Taxes	(33.0)	(32.2)
Deferred Fuel Over/Under-Recovery, Net	31.1	8.2
Provision for Refund	(4.4)	(25.2)
Change in Other Noncurrent Assets	(1.6)	2.9
Change in Other Noncurrent Liabilities	13.5	2.0
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	(5.8)	(26.1)
Fuel, Materials and Supplies	(60.4)	(19.3)
Accounts Payable	2.9	5.5
Accrued Taxes, Net	52.0	47.7
Other Current Assets	0.2	(1.4)
Other Current Liabilities	(32.6)	23.4
Net Cash Flows from (Used for) Operating Activities	160.5	151.7
Investing Activities
Construction Expenditures	(228.5)	(185.2)
Change in Advances to Affiliates, Net	0.0	81.4
Other Investing Activities	4.3	(2.2)
Net Cash Flows from (Used for) Investing Activities	(224.2)	(106.0)
Financing Activities
Change in Short-term Debt, Net	18.7	0.0
Change in Advances from Affiliates, Net	70.5	55.3
Retirement of Long-term Debt	(18.1)	(56.6)
Principal Payments for Finance Leases	(5.5)	(5.5)
Dividends Paid on Common Stock	0.0	(37.5)
Dividends Paid on Common Stock	(1.9)	(2.2)
Other Financing Activities	0.2	0.3
Net Cash Flows from (Used for) Financing Activities	63.9	(46.2)
Net Increase (Decrease) in Cash and Cash Equivalents	0.2	(0.5)
Cash and Cash Equivalents at Beginning of Period	1.6	24.5
Cash and Cash Equivalents at End of Period	1.8	24.0
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	57.0	57.1
Net Cash Paid (Received) for Income Taxes	8.1	6.2
Noncash Acquisitions Under Finance Leases	4.3	2.6
Construction Expenditures Included in Current Liabilities as of June 30,	33.7	40.9
Noncontrolling Interest [Member]
Supplementary Information
Noncash Contribution of Assets by Noncontrolling Interest	$ 0.0	134.8
Retained Earnings [Member]
Supplementary Information
Stockholders' Equity, Other		$ 62.0