Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Operating Activities
Net Income (Loss)	$ 1,767.1	$ 1,566.5
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	1,873.6	1,695.5
Deferred Income Taxes	15.9	43.0
Allowance for Equity Funds Used During Construction	(122.3)	(92.4)
Mark-to-Market of Risk Management Contracts	(41.6)	(95.4)
Amortization of Nuclear Fuel	71.6	82.6
Property Taxes	341.7	304.8
Deferred Fuel Over/Under-Recovery, Net	93.7	210.6
Recovery of Ohio Capacity Costs, Net	34.1	52.7
Refund of Global Settlement	(12.4)	(5.5)
Change in Other Noncurrent Assets	(9.6)	161.6
Change in Other Noncurrent Liabilities	(16.3)	141.9
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	125.0	(52.3)
Fuel, Materials and Supplies	(116.6)	98.7
Accounts Payable	(32.4)	(45.0)
Accrued Taxes, Net	(359.9)	(247.5)
Other Current Assets	60.2	11.7
Other Current Liabilities	(321.9)	101.1
Net Cash Flows from (Used for) Operating Activities	3,349.9	3,932.6
Investing Activities
Construction Expenditures	(4,336.0)	(4,688.4)
Acquisitions of Assets	(921.3)	0.0
Purchases of Investment Securities	(951.5)	(1,591.2)
Sales of Investment Securities	874.2	1,550.9
Acquisitions of Nuclear Fuel	(91.9)	(26.1)
Other Investing Activities	68.9	66.1
Net Cash Flows from (Used for) Investing Activities	(5,357.6)	(4,688.7)
Financing Activities
Issuance of Common Stock, Net	44.7	62.5
Issuance of Long-term Debt	3,492.4	3,572.0
Commercial Paper and Credit Facility Borrowings	0.0	205.6
Change in Short-term Debt, Net	600.0	604.0
Retirement of Long-term Debt	(1,023.5)	(1,959.5)
Commercial Paper and Credit Facility Repayments	0.0	(205.6)
Make Whole Premium on Extinguishment of Long-term Debt	(5.0)	(10.3)
Principal Payments for Finance Leases	(44.5)	(49.4)
Dividends Paid on Common Stock	(1,002.0)	(922.5)
Other Financing Activities	(8.7)	(15.8)
Net Cash Flows from (Used for) Financing Activities	2,053.4	1,281.0
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	45.7	524.9
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	444.1	412.6
Cash and Cash Equivalents at Beginning of Period	234.1
Cash, Cash Equivalents and Restricted Cash at End of Period	489.8	937.5
Cash and Cash Equivalents at End of Period	348.8
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	689.7	631.3
Net Cash Paid (Received) for Income Taxes	22.8	(27.9)
Noncash Acquisitions Under Finance Leases	66.7	43.5
Construction Expenditures Included in Current Liabilities as of September 30,	1,018.9	882.3
Acquisition of Nuclear Fuel Included in Current Liabilities as of September 30,	0.0	12.1
Noncash Contribution of Assets by Noncontrolling Interest	0.0	84.0
Expected Reimbursement for Spent Nuclear Fuel Dry Cask Storage	0.0	2.1
Noncash or Part Noncash Acquisition, Value of Liabilities Assumed	32.4	0.0
AEP Texas Inc. [Member]
Operating Activities
Net Income (Loss)	192.0	151.1
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	464.8	364.9
Deferred Income Taxes	(0.6)	(21.2)
Allowance for Equity Funds Used During Construction	(8.3)	(15.2)
Mark-to-Market of Risk Management Contracts	0.2	0.0
Change in Other Noncurrent Assets	0.5	(55.7)
Change in Other Noncurrent Liabilities	6.5	67.1
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	(50.0)	(26.5)
Fuel, Materials and Supplies	(0.1)	(2.4)
Accounts Payable	17.8	(19.1)
Accrued Taxes, Net	(33.4)	40.0
Other Current Assets	(0.7)	(6.3)
Other Current Liabilities	(12.9)	14.1
Net Cash Flows from (Used for) Operating Activities	575.8	490.8
Investing Activities
Construction Expenditures	(954.5)	(1,096.1)
Change in Advances to Affiliates, Net	0.3	103.9
Other Investing Activities	18.4	31.1
Net Cash Flows from (Used for) Investing Activities	(935.8)	(961.1)
Financing Activities
Capital Contributions from Parent	200.0	100.0
Issuance of Long-term Debt	627.5	494.0
Change in Advances from Affiliates, Net	(141.2)	77.8
Retirement of Long-term Debt	(366.8)	(231.7)
Principal Payments for Finance Leases	(3.8)	(3.6)
Other Financing Activities	(1.1)	0.9
Net Cash Flows from (Used for) Financing Activities	314.6	437.4
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	(45.4)	(32.9)
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	159.8	157.2
Cash and Cash Equivalents at Beginning of Period	3.1
Cash, Cash Equivalents and Restricted Cash at End of Period	114.4	124.3
Cash and Cash Equivalents at End of Period	0.1
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	95.1	92.2
Net Cash Paid (Received) for Income Taxes	28.7	(14.2)
Noncash Acquisitions Under Finance Leases	6.9	8.9
Construction Expenditures Included in Current Liabilities as of September 30,	183.6	176.4
AEP Transmission Co [Member]
Operating Activities
Net Income (Loss)	347.9	244.2
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	128.4	97.5
Deferred Income Taxes	36.7	76.3
Allowance for Equity Funds Used During Construction	(61.1)	(48.7)
Property Taxes	110.7	86.9
Long-term Accounts Receivable - Affiliated	(4.8)	(3.1)
Change in Other Noncurrent Assets	5.8	12.7
Change in Other Noncurrent Liabilities	(3.8)	18.0
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	(5.1)	23.5
Fuel, Materials and Supplies	3.9	(2.8)
Accounts Payable	4.1	3.3
Accrued Taxes, Net	(92.8)	(73.2)
Accrued Interest	23.8	20.9
Other Current Assets	(1.0)	(0.5)
Other Current Liabilities	(8.5)	(28.0)
Net Cash Flows from (Used for) Operating Activities	484.2	427.0
Investing Activities
Construction Expenditures	(959.9)	(1,171.8)
Change in Advances to Affiliates, Net	(178.3)	(131.7)
Acquisitions of Assets	(7.6)	(13.2)
Other Investing Activities	12.0	1.2
Net Cash Flows from (Used for) Investing Activities	(1,133.8)	(1,315.5)
Financing Activities
Capital Contributions from Parent	0.0	582.0
Issuance of Long-term Debt	685.9	321.1
Change in Advances from Affiliates, Net	(36.3)	(14.6)
Principal Payments for Finance Leases	0.0
Net Cash Flows from (Used for) Financing Activities	649.6	888.5
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	43.0	38.4
Net Cash Paid (Received) for Income Taxes	29.8	(32.1)
Construction Expenditures Included in Current Liabilities as of September 30,	315.1	237.0
Appalachian Power Co [Member]
Operating Activities
Net Income (Loss)	293.5	290.0
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	348.3	319.5
Deferred Income Taxes	(101.9)	(83.8)
Carrying Costs Income	0.0	(1.2)
Allowance for Equity Funds Used During Construction	(12.5)	(9.6)
Mark-to-Market of Risk Management Contracts	2.2	(43.7)
Deferred Fuel Over/Under-Recovery, Net	60.8	12.8
Change in Other Noncurrent Assets	6.7	94.8
Change in Other Noncurrent Liabilities	(29.6)	3.8
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	61.7	39.4
Fuel, Materials and Supplies	(49.2)	53.0
Accounts Payable	40.1	(21.5)
Accrued Taxes, Net	(30.2)	(20.2)
Other Current Assets	6.8	(7.9)
Other Current Liabilities	(25.1)	64.1
Net Cash Flows from (Used for) Operating Activities	571.6	690.7
Investing Activities
Construction Expenditures	(607.1)	(575.8)
Change in Advances to Affiliates, Net	0.3	0.4
Other Investing Activities	22.8	10.0
Net Cash Flows from (Used for) Investing Activities	(584.0)	(565.4)
Financing Activities
Issuance of Long-term Debt	478.2	103.3
Change in Advances from Affiliates, Net	(165.2)	(87.5)
Retirement of Long-term Debt	(180.4)	(24.0)
Principal Payments for Finance Leases	(5.0)	(5.2)
Dividends Paid on Common Stock	(125.0)	(120.0)
Other Financing Activities	0.6	1.0
Net Cash Flows from (Used for) Financing Activities	3.2	(132.4)
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	(9.2)	(7.1)
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	29.8	19.2
Cash and Cash Equivalents at Beginning of Period	4.2
Cash, Cash Equivalents and Restricted Cash at End of Period	20.6	12.1
Cash and Cash Equivalents at End of Period	3.5
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	120.6	104.5
Net Cash Paid (Received) for Income Taxes	58.7	26.7
Noncash Acquisitions Under Finance Leases	7.1	3.9
Construction Expenditures Included in Current Liabilities as of September 30,	134.2	87.6
Indiana Michigan Power Co [Member]
Operating Activities
Net Income (Loss)	248.0	231.6
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	261.6	207.1
Rent - Rockport Plant, Unit 2	(58.9)	0.0
Deferred Income Taxes	(29.9)	28.1
Deferral of Incremental Nuclear Refueling Outage Expenses, Net	(11.6)	13.5
Allowance for Equity Funds Used During Construction	(16.4)	(8.0)
Mark-to-Market of Risk Management Contracts	(1.6)	(0.3)
Amortization of Nuclear Fuel	71.6	82.6
Deferred Fuel Over/Under-Recovery, Net	(20.0)	29.6
Change in Other Noncurrent Assets	46.0	(12.0)
Change in Other Noncurrent Liabilities	13.8	46.3
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	50.5	6.5
Fuel, Materials and Supplies	(4.6)	(1.1)
Accounts Payable	(7.3)	(34.7)
Accrued Taxes, Net	(49.4)	(7.1)
Payments for Rockport Plant, Unit 2 Operating Lease	(36.9)	0.0
Other Current Assets	7.8	4.9
Other Current Liabilities	(49.7)	(15.7)
Net Cash Flows from (Used for) Operating Activities	530.8	571.3
Investing Activities
Construction Expenditures	(431.7)	(434.5)
Change in Advances to Affiliates, Net	(0.5)	(60.1)
Purchases of Investment Securities	(915.7)	(1,589.0)
Sales of Investment Securities	871.4	1,550.9
Acquisitions of Nuclear Fuel	(91.9)	(26.1)
Other Investing Activities	10.5	9.2
Net Cash Flows from (Used for) Investing Activities	(557.9)	(549.6)
Financing Activities
Issuance of Long-term Debt	62.9	1,168.1
Change in Advances from Affiliates, Net	101.3	(211.6)
Retirement of Long-term Debt	(73.6)	(856.1)
Principal Payments for Finance Leases	(4.0)	(7.3)
Dividends Paid on Common Stock	(60.0)	(105.5)
Other Financing Activities	0.6	(9.0)
Net Cash Flows from (Used for) Financing Activities	27.2	(21.4)
Net Increase (Decrease) in Cash and Cash Equivalents	0.1	0.3
Cash and Cash Equivalents at Beginning of Period	2.4	1.3
Cash and Cash Equivalents at End of Period	2.5	1.6
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	98.7	104.4
Net Cash Paid (Received) for Income Taxes	40.2	(26.5)
Noncash Acquisitions Under Finance Leases	8.1	4.4
Construction Expenditures Included in Current Liabilities as of September 30,	76.3	66.4
Acquisition of Nuclear Fuel Included in Current Liabilities as of September 30,	0.0	12.1
Expected Reimbursement for Spent Nuclear Fuel Dry Cask Storage	0.0	2.1
Ohio Power Co [Member]
Operating Activities
Net Income (Loss)	247.7	237.1
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	176.8	200.3
Amortization Of Generation Deferrals	65.3	171.9
Deferred Income Taxes	16.8	(71.9)
Carrying Costs Income	(0.7)	(1.5)
Allowance for Equity Funds Used During Construction	(14.1)	(7.8)
Mark-to-Market of Risk Management Contracts	13.3	(37.1)
Property Taxes	197.7	191.1
Refund of Global Settlement	(12.4)	(5.5)
Reversal of a Regulatory Provision	(56.2)	0.0
Change in Regulatory Assets	(28.1)	180.9
Change in Other Noncurrent Assets	(19.4)	0.8
Change in Other Noncurrent Liabilities	(51.1)	62.5
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	90.0	21.3
Fuel, Materials and Supplies	(9.6)	(3.7)
Accounts Payable	(12.3)	(31.8)
Accrued Taxes, Net	(245.9)	(210.6)
Other Current Assets	(9.0)	7.6
Other Current Liabilities	(40.0)	(4.3)
Net Cash Flows from (Used for) Operating Activities	309.5	700.8
Investing Activities
Construction Expenditures	(570.6)	(538.5)
Other Investing Activities	20.0	15.5
Net Cash Flows from (Used for) Investing Activities	(550.6)	(523.0)
Financing Activities
Issuance of Long-term Debt	444.3	392.8
Change in Advances from Affiliates, Net	(96.5)	155.1
Retirement of Long-term Debt	(48.0)	(397.0)
Principal Payments for Finance Leases	(2.6)	(2.9)
Dividends Paid on Common Stock	(85.0)	(337.5)
Other Financing Activities	1.1	0.7
Net Cash Flows from (Used for) Financing Activities	213.3	(188.8)
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	(27.8)	(11.0)
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	32.5	29.7
Cash and Cash Equivalents at Beginning of Period	4.9
Cash, Cash Equivalents and Restricted Cash at End of Period	4.7	18.7
Cash and Cash Equivalents at End of Period	4.7
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	61.3	67.3
Net Cash Paid (Received) for Income Taxes	25.7	54.1
Noncash Acquisitions Under Finance Leases	8.6	3.0
Construction Expenditures Included in Current Liabilities as of September 30,	99.9	66.0
Public Service Co Of Oklahoma [Member]
Operating Activities
Net Income (Loss)	148.4	89.8
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	125.4	120.5
Deferred Income Taxes	(9.7)	(13.4)
Allowance for Equity Funds Used During Construction	(1.5)	0.3
Mark-to-Market of Risk Management Contracts	(12.0)	(11.5)
Property Taxes	(9.6)	(9.6)
Deferred Fuel Over/Under-Recovery, Net	49.8	73.3
Change in Other Noncurrent Assets	4.6	6.9
Change in Other Noncurrent Liabilities	(0.2)	14.6
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	9.1	(3.4)
Fuel, Materials and Supplies	(1.9)	(1.5)
Accounts Payable	(5.8)	6.9
Accrued Taxes, Net	19.0	38.4
Other Current Assets	(2.4)	0.3
Other Current Liabilities	1.1	15.1
Net Cash Flows from (Used for) Operating Activities	314.3	326.7
Investing Activities
Construction Expenditures	(198.7)	(162.8)
Change in Advances to Affiliates, Net	(95.1)	0.0
Other Investing Activities	2.1	3.9
Net Cash Flows from (Used for) Investing Activities	(291.7)	(158.9)
Financing Activities
Issuance of Long-term Debt	349.8	0.0
Change in Advances from Affiliates, Net	(105.5)	(127.6)
Retirement of Long-term Debt	(250.4)	(0.3)
Make Whole Premium on Extinguishment of Long-term Debt	(3.0)	0.0
Principal Payments for Finance Leases	(2.2)	(2.5)
Dividends Paid on Common Stock	(11.3)	(37.5)
Other Financing Activities	0.9	0.4
Net Cash Flows from (Used for) Financing Activities	(21.7)	(167.5)
Net Increase (Decrease) in Cash and Cash Equivalents	0.9	0.3
Cash and Cash Equivalents at Beginning of Period	2.0	1.6
Cash and Cash Equivalents at End of Period	2.9	1.9
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	46.5	42.0
Net Cash Paid (Received) for Income Taxes	16.0	1.6
Noncash Acquisitions Under Finance Leases	3.4	2.3
Construction Expenditures Included in Current Liabilities as of September 30,	31.5	24.3
Southwestern Electric Power Co [Member]
Operating Activities
Net Income (Loss)	147.6	141.7
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	187.1	175.9
Deferred Income Taxes	(15.9)	2.0
Allowance for Equity Funds Used During Construction	(4.5)	(3.8)
Mark-to-Market of Risk Management Contracts	(2.5)	2.5
Property Taxes	(16.1)	(15.8)
Deferred Fuel Over/Under-Recovery, Net	14.1	4.4
Provision for Refund	(25.3)	0.0
Change in Other Noncurrent Assets	3.5	(8.9)
Change in Other Noncurrent Liabilities	5.8	52.1
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	(17.2)	44.3
Fuel, Materials and Supplies	(17.7)	5.0
Accounts Payable	(12.8)	(29.9)
Accrued Taxes, Net	54.1	38.4
Other Current Assets	(4.5)	3.2
Other Current Liabilities	(13.9)	4.2
Net Cash Flows from (Used for) Operating Activities	307.1	415.3
Investing Activities
Construction Expenditures	(277.3)	(336.6)
Change in Advances to Affiliates, Net	74.9	(516.6)
Other Investing Activities	(1.2)	1.2
Net Cash Flows from (Used for) Investing Activities	(203.6)	(852.0)
Financing Activities
Issuance of Long-term Debt	0.0	1,015.4
Change in Short-term Debt, Net	0.0	(2.6)
Change in Advances from Affiliates, Net	0.0	(118.7)
Retirement of Long-term Debt	(58.2)	(385.3)
Principal Payments for Finance Leases	(8.1)	(8.5)
Dividends Paid on Common Stock	(37.5)	(60.0)
Dividends Paid on Common Stock	(3.3)	(3.2)
Other Financing Activities	0.5	0.5
Net Cash Flows from (Used for) Financing Activities	(106.6)	437.6
Net Increase (Decrease) in Cash and Cash Equivalents	(3.1)	0.9
Cash and Cash Equivalents at Beginning of Period	24.5	1.6
Cash and Cash Equivalents at End of Period	21.4	2.5
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	95.1	102.5
Net Cash Paid (Received) for Income Taxes	7.3	12.9
Noncash Acquisitions Under Finance Leases	4.7	3.2
Construction Expenditures Included in Current Liabilities as of September 30,	52.0	37.0
Noncontrolling Interest [Member]
Supplementary Information
Noncash Contribution of Assets by Noncontrolling Interest	$ 253.4
Noncontrolling Interest [Member] | AEP Wind Holdings LLC [Member]
Supplementary Information
Noncash Contribution of Assets by Noncontrolling Interest		$ 0.0