Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Operating Activities
Net Income (Loss)	$ 1,762.0	$ 1,767.1
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	1,996.3	1,873.6
Deferred Income Taxes	142.5	15.9
Allowance for Equity Funds Used During Construction	(111.7)	(122.3)
Mark-to-Market of Risk Management Contracts	46.4	(41.6)
Amortization of Nuclear Fuel	67.2	71.6
Pension Contributions to Qualified Plan Trust	(110.3)	0.0
Property Taxes	396.9	341.7
Deferred Fuel Over/Under-Recovery, Net	27.4	93.7
Recovery of Ohio Capacity Costs, Net	0.0	34.1
Refund of Global Settlement	0.0	(12.4)
Change in Other Noncurrent Assets	(219.6)	(9.6)
Change in Other Noncurrent Liabilities	(25.1)	(16.3)
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	(138.9)	125.0
Fuel, Materials and Supplies	(97.4)	(116.6)
Accounts Payable	21.9	(32.4)
Accrued Taxes, Net	(502.9)	(359.9)
Other Current Assets	26.0	60.2
Other Current Liabilities	(358.5)	(321.9)
Net Cash Flows from (Used for) Operating Activities	2,922.2	3,349.9
Investing Activities
Construction Expenditures	(4,690.4)	(4,336.0)
Purchases of Investment Securities	(1,329.5)	(951.5)
Sales of Investment Securities	1,293.0	874.2
Acquisitions of Nuclear Fuel	(68.4)	(91.9)
Acquisitions of Assets	0.0	(921.3)
Other Investing Activities	88.0	68.9
Net Cash Flows from (Used for) Investing Activities	(4,707.3)	(5,357.6)
Financing Activities
Issuance of Common Stock	136.5	44.7
Issuance of Long-term Debt	3,985.8	3,492.4
Issuance of Short-term Debt with Original Maturities greater than 90 Days	1,304.5	0.0
Change in Short-term Debt, Net	(1,445.8)	600.0
Retirement of Long-term Debt	(700.5)	(1,023.5)
Make Whole Premium on Extinguishment of Long-term Debt	0.0	(5.0)
Redemption of Short-term Debt with Original Maturities Greater than 90 Days	(300.0)	0.0
Principal Payments for Finance Leases Obligations	(46.3)	(44.5)
Dividends Paid on Common Stock	(1,055.7)	(1,002.0)
Redemption of Noncontrolling Interest in Trent & Desert Sky Windfarms	(56.5)	0.0
Other Financing Activities	(5.7)	(8.7)
Net Cash Flows from (Used for) Financing Activities	1,816.3	2,053.4
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	31.2	45.7
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	463.8	489.8
Cash and Cash Equivalents at End of Period	409.7
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	690.5	689.7
Net Cash Paid (Received) for Income Taxes	(23.9)	22.8
Noncash Acquisitions Under Finance Leases	33.0	66.7
Construction Expenditures Included in Current Liabilities as of September 30,	830.1	1,018.9
Construction Expenditures Included in Noncurrent Liabilities as of September 30,	8.3	0.0
Acquisition of Nuclear Fuel Included in Current Liabilities as of September 30,	1.0	0.0
Expected Reimbursement for Spent Nuclear Fuel Dry Cask Storage	2.4	0.0
Liabilities assumed with Sempra Renewable LLC and Santa Rita East Acquisition	0.0	32.4
AEP Texas Inc. [Member]
Operating Activities
Net Income (Loss)	197.1	192.0
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	435.8	464.8
Deferred Income Taxes	(11.5)	(0.6)
Allowance for Equity Funds Used During Construction	(14.4)	(8.3)
Mark-to-Market of Risk Management Contracts	0.1	0.2
Pension Contributions to Qualified Plan Trust	(11.3)	0.0
Change in Other Noncurrent Assets	(77.3)	0.5
Change in Other Noncurrent Liabilities	(30.0)	6.5
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	(40.2)	(50.0)
Fuel, Materials and Supplies	(9.4)	(0.1)
Accounts Payable	24.2	17.8
Accrued Taxes, Net	73.4	(33.4)
Other Current Assets	(0.8)	(0.7)
Other Current Liabilities	(49.8)	(12.9)
Net Cash Flows from (Used for) Operating Activities	485.9	575.8
Investing Activities
Construction Expenditures	(976.1)	(954.5)
Change in Advances to Affiliates, Net	58.8	0.3
Other Investing Activities	24.1	18.4
Net Cash Flows from (Used for) Investing Activities	(893.2)	(935.8)
Financing Activities
Capital Contributions from Parent	0.0	200.0
Issuance of Long-term Debt	652.8	627.5
Change in Short-term Debt, Net	2.0	0.0
Change in Advances from Affiliates, Net	0.0	(141.2)
Retirement of Long-term Debt	(356.5)	(366.8)
Principal Payments for Finance Leases Obligations	(4.7)	(3.8)
Other Financing Activities	0.8	(1.1)
Net Cash Flows from (Used for) Financing Activities	294.4	314.6
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	(112.9)	(45.4)
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	44.9	114.4
Cash and Cash Equivalents at End of Period	0.1
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	102.0	95.1
Net Cash Paid (Received) for Income Taxes	(55.6)	28.7
Noncash Acquisitions Under Finance Leases	5.1	6.9
Construction Expenditures Included in Current Liabilities as of September 30,	167.6	183.6
AEP Transmission Co [Member]
Operating Activities
Net Income (Loss)	309.1	347.9
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	176.4	128.4
Deferred Income Taxes	65.4	36.7
Allowance for Equity Funds Used During Construction	(54.9)	(61.1)
Property Taxes	136.3	110.7
Change in Other Noncurrent Assets	(1.5)	1.0
Change in Other Noncurrent Liabilities	19.5	(3.8)
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	(30.1)	(5.1)
Fuel, Materials and Supplies	0.2	3.9
Accounts Payable	26.0	4.1
Accrued Taxes, Net	(139.0)	(92.8)
Accrued Interest	29.0	23.8
Other Current Assets	9.1	(1.0)
Other Current Liabilities	(10.7)	(8.5)
Net Cash Flows from (Used for) Operating Activities	534.8	484.2
Investing Activities
Construction Expenditures	(1,163.8)	(959.9)
Change in Advances to Affiliates, Net	(21.3)	(178.3)
Acquisitions of Assets	(3.6)	(7.6)
Other Investing Activities	4.7	12.0
Net Cash Flows from (Used for) Investing Activities	(1,184.0)	(1,133.8)
Financing Activities
Capital Contributions from Parent	185.0	0.0
Issuance of Long-term Debt	519.4	685.9
Change in Advances from Affiliates, Net	(50.2)	(36.3)
Dividends Paid on Common Stock	(5.0)	0.0
Net Cash Flows from (Used for) Financing Activities	649.2	649.6
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	63.3	43.0
Net Cash Paid (Received) for Income Taxes	1.9	29.8
Construction Expenditures Included in Current Liabilities as of September 30,	283.6	315.1
Appalachian Power Co [Member]
Operating Activities
Net Income (Loss)	313.2	293.5
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	366.0	348.3
Deferred Income Taxes	(28.2)	(101.9)
Allowance for Equity Funds Used During Construction	(11.5)	(12.5)
Mark-to-Market of Risk Management Contracts	8.0	2.2
Pension Contributions to Qualified Plan Trust	(7.0)	0.0
Deferred Fuel Over/Under-Recovery, Net	38.8	60.8
Change in Other Noncurrent Assets	5.4	6.7
Change in Other Noncurrent Liabilities	(26.0)	(29.6)
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	7.2	61.7
Fuel, Materials and Supplies	12.4	(49.2)
Accounts Payable	(74.0)	40.1
Accrued Taxes, Net	1.9	(30.2)
Other Current Assets	10.1	6.8
Other Current Liabilities	(9.7)	(25.1)
Net Cash Flows from (Used for) Operating Activities	606.6	571.6
Investing Activities
Construction Expenditures	(566.6)	(607.1)
Change in Advances to Affiliates, Net	(137.4)	0.3
Other Investing Activities	4.6	22.8
Net Cash Flows from (Used for) Investing Activities	(699.4)	(584.0)
Financing Activities
Issuance of Long-term Debt	557.2	478.2
Change in Advances from Affiliates, Net	(232.4)	(165.2)
Retirement of Long-term Debt	(90.3)	(180.4)
Principal Payments for Finance Leases Obligations	(5.6)	(5.0)
Dividends Paid on Common Stock	(150.0)	(125.0)
Other Financing Activities	0.3	0.6
Net Cash Flows from (Used for) Financing Activities	79.2	3.2
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	(13.6)	(9.2)
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	13.2	20.6
Cash and Cash Equivalents at End of Period	3.9
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	130.0	120.6
Net Cash Paid (Received) for Income Taxes	(10.7)	58.7
Noncash Acquisitions Under Finance Leases	3.0	7.1
Construction Expenditures Included in Current Liabilities as of September 30,	90.0	134.2
Indiana Michigan Power Co [Member]
Operating Activities
Net Income (Loss)	232.8	248.0
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	303.6	261.6
Rockport Plant, Unit 2 Operating Lease Amortization	51.9	58.9
Deferred Income Taxes	(6.1)	(29.9)
Deferral of Incremental Nuclear Refueling Outage Expenses, Net	21.3	(11.6)
Allowance for Equity Funds Used During Construction	(8.8)	(16.4)
Mark-to-Market of Risk Management Contracts	5.6	(1.6)
Amortization of Nuclear Fuel	67.2	71.6
Pension Contributions to Qualified Plan Trust	(6.4)	0.0
Deferred Fuel Over/Under-Recovery, Net	23.4	(20.0)
Change in Other Noncurrent Assets	40.8	46.0
Change in Other Noncurrent Liabilities	30.2	13.8
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	32.2	50.5
Fuel, Materials and Supplies	(15.4)	(4.6)
Accounts Payable	(0.9)	(7.3)
Accrued Taxes, Net	(84.4)	(49.4)
Operating Lease, Payments	(36.9)	(36.9)
Other Current Assets	6.6	7.8
Other Current Liabilities	(59.1)	(49.7)
Net Cash Flows from (Used for) Operating Activities	597.6	530.8
Investing Activities
Construction Expenditures	(409.1)	(431.7)
Change in Advances to Affiliates, Net	(0.1)	(0.5)
Purchases of Investment Securities	(1,290.0)	(915.7)
Sales of Investment Securities	1,257.1	871.4
Acquisitions of Nuclear Fuel	(68.4)	(91.9)
Other Investing Activities	8.3	10.5
Net Cash Flows from (Used for) Investing Activities	(502.2)	(557.9)
Financing Activities
Issuance of Long-term Debt	0.0	62.9
Change in Advances from Affiliates, Net	44.7	101.3
Retirement of Long-term Debt	(71.1)	(73.6)
Principal Payments for Finance Leases Obligations	(4.8)	(4.0)
Dividends Paid on Common Stock	(63.7)	(60.0)
Other Financing Activities	0.3	0.6
Net Cash Flows from (Used for) Financing Activities	(94.6)	27.2
Net Increase (Decrease) in Cash and Cash Equivalents	0.8	0.1
Cash and Cash Equivalents at Beginning of Period	2.0	2.4
Cash and Cash Equivalents at End of Period	2.8	2.5
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	97.5	98.7
Net Cash Paid (Received) for Income Taxes	59.7	40.2
Noncash Acquisitions Under Finance Leases	1.9	8.1
Construction Expenditures Included in Current Liabilities as of September 30,	57.6	76.3
Acquisition of Nuclear Fuel Included in Current Liabilities as of September 30,	1.0	0.0
Expected Reimbursement for Spent Nuclear Fuel Dry Cask Storage	2.4	0.0
Ohio Power Co [Member]
Operating Activities
Net Income (Loss)	215.0	247.7
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	204.4	176.8
Amortization Of Generation Deferrals	0.0	65.3
Deferred Income Taxes	35.6	16.8
Carrying Costs Income	(1.3)	(0.7)
Allowance for Equity Funds Used During Construction	(9.3)	(14.1)
Mark-to-Market of Risk Management Contracts	9.7	13.3
Pension Contributions to Qualified Plan Trust	(0.1)
Property Taxes	225.1	197.7
Refund of Global Settlement	0.0	(12.4)
Reversal of a Regulatory Provision	0.0	(56.2)
Change in Other Noncurrent Assets	(93.8)	(47.5)
Change in Other Noncurrent Liabilities	(58.3)	(51.1)
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	33.4	90.0
Fuel, Materials and Supplies	(19.8)	(9.6)
Accounts Payable	(19.9)	(12.3)
Accrued Taxes, Net	(266.2)	(245.9)
Other Current Assets	(2.5)	(9.0)
Other Current Liabilities	(23.3)	(40.0)
Net Cash Flows from (Used for) Operating Activities	230.1	309.5
Investing Activities
Construction Expenditures	(604.6)	(570.6)
Other Investing Activities	14.1	20.0
Net Cash Flows from (Used for) Investing Activities	(590.5)	(550.6)
Financing Activities
Issuance of Long-term Debt	347.0	444.3
Change in Advances from Affiliates, Net	84.9	(96.5)
Retirement of Long-term Debt	(0.1)	(48.0)
Principal Payments for Finance Leases Obligations	(3.5)	(2.6)
Dividends Paid on Common Stock	(65.6)	(85.0)
Other Financing Activities	0.6	1.1
Net Cash Flows from (Used for) Financing Activities	363.3	213.3
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	2.9	(27.8)
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	6.6	4.7
Cash and Cash Equivalents at End of Period	6.6
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	69.7	61.3
Net Cash Paid (Received) for Income Taxes	(6.0)	25.7
Noncash Acquisitions Under Finance Leases	5.2	8.6
Construction Expenditures Included in Current Liabilities as of September 30,	75.9	99.9
Public Service Co Of Oklahoma [Member]
Operating Activities
Net Income (Loss)	116.4	148.4
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	129.8	125.4
Deferred Income Taxes	(3.2)	(9.7)
Allowance for Equity Funds Used During Construction	(3.2)	(1.5)
Mark-to-Market of Risk Management Contracts	(0.3)	(12.0)
Property Taxes	(10.6)	(9.6)
Deferred Fuel Over/Under-Recovery, Net	(46.6)	49.8
Change in Other Noncurrent Assets	(7.2)	4.6
Change in Other Noncurrent Liabilities	6.1	(0.2)
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	(5.6)	9.1
Fuel, Materials and Supplies	(17.2)	(1.9)
Accounts Payable	(26.1)	(5.8)
Accrued Taxes, Net	36.9	19.0
Other Current Assets	(0.1)	(2.4)
Other Current Liabilities	(16.4)	1.1
Net Cash Flows from (Used for) Operating Activities	152.7	314.3
Investing Activities
Construction Expenditures	(256.4)	(198.7)
Change in Advances to Affiliates, Net	38.8	(95.1)
Other Investing Activities	3.9	2.1
Net Cash Flows from (Used for) Investing Activities	(213.7)	(291.7)
Financing Activities
Issuance of Long-term Debt	0.0	349.8
Change in Advances from Affiliates, Net	77.8	(105.5)
Retirement of Long-term Debt	(13.0)	(250.4)
Principal Payments for Finance Leases Obligations	(2.7)	(2.2)
Dividends Paid on Common Stock	0.0	(11.3)
Other Financing Activities	0.4	(2.1)
Net Cash Flows from (Used for) Financing Activities	62.5	(21.7)
Net Increase (Decrease) in Cash and Cash Equivalents	1.5	0.9
Cash and Cash Equivalents at Beginning of Period	1.5	2.0
Cash and Cash Equivalents at End of Period	3.0	2.9
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	45.5	46.5
Net Cash Paid (Received) for Income Taxes	(9.5)	16.0
Noncash Acquisitions Under Finance Leases	3.0	3.4
Construction Expenditures Included in Current Liabilities as of September 30,	23.5	31.5
Southwestern Electric Power Co [Member]
Operating Activities
Net Income (Loss)	163.9	147.6
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	203.9	187.1
Deferred Income Taxes	(0.3)	(15.9)
Allowance for Equity Funds Used During Construction	(5.7)	(4.5)
Mark-to-Market of Risk Management Contracts	(2.3)	(2.5)
Pension Contributions to Qualified Plan Trust	(8.9)	0.0
Property Taxes	(16.5)	(16.1)
Deferred Fuel Over/Under-Recovery, Net	16.3	14.1
Change in Regulatory Assets	(64.5)	5.7
Provision for Refund	(2.0)	(25.3)
Change in Other Noncurrent Assets	3.2	(2.2)
Change in Other Noncurrent Liabilities	21.0	5.8
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	8.0	(17.2)
Fuel, Materials and Supplies	(70.9)	(17.7)
Accounts Payable	88.0	(12.8)
Accrued Taxes, Net	46.6	54.1
Other Current Assets	1.3	(4.5)
Other Current Liabilities	(50.3)	(13.9)
Net Cash Flows from (Used for) Operating Activities	332.8	307.1
Investing Activities
Construction Expenditures	(319.5)	(277.3)
Change in Advances to Affiliates, Net	0.0	74.9
Other Investing Activities	4.8	(1.2)
Net Cash Flows from (Used for) Investing Activities	(314.7)	(203.6)
Financing Activities
Change in Short-term Debt, Net	23.7	0.0
Change in Advances from Affiliates, Net	11.9	0.0
Retirement of Long-term Debt	(19.7)	(58.2)
Principal Payments for Finance Leases Obligations	(8.0)	(8.1)
Dividends Paid on Common Stock	0.0	(37.5)
Dividends Paid on Common Stock	(2.3)	(3.3)
Other Financing Activities	0.3	0.5
Net Cash Flows from (Used for) Financing Activities	5.9	(106.6)
Net Increase (Decrease) in Cash and Cash Equivalents	24.0	(3.1)
Cash and Cash Equivalents at Beginning of Period	1.6	24.5
Cash and Cash Equivalents at End of Period	25.6	21.4
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	95.2	95.1
Net Cash Paid (Received) for Income Taxes	11.9	7.3
Noncash Acquisitions Under Finance Leases	5.9	4.7
Construction Expenditures Included in Current Liabilities as of September 30,	50.6	52.0
Noncontrolling Interest [Member]
Supplementary Information
Noncontrolling Interest assumed with Sempra Renewable LLC and Santa Rita East Acquisition	0.0	253.4
Retained Earnings [Member]
Supplementary Information
Forward Equity Purchase Contract Included in Current and Noncurrent Liabilities as of September 30	$ 120.6	$ 52.4