Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Operating Activities
Net Income (Loss)	$ 1,033.2	$ 986.8
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	1,228.4	1,092.9
Deferred Income Taxes	(35.5)	149.7
Allowance for Equity Funds Used During Construction	(79.3)	(61.5)
Mark-to-Market of Risk Management Contracts	(72.9)	(112.9)
Amortization of Nuclear Fuel	46.1	51.4
Property Taxes	137.6	119.9
Deferred Fuel Over/Under-Recovery, Net	36.7	12.3
Recovery of Ohio Capacity Costs, Net	29.0	35.8
Refund of Global Settlement	(8.2)	(5.5)
Change in Other Noncurrent Assets	(73.5)	10.4
Change in Other Noncurrent Liabilities	(53.6)	185.1
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	165.5	(209.9)
Fuel, Materials and Supplies	(114.6)	31.2
Accounts Payable	(72.4)	(53.6)
Accrued Taxes, Net	(170.1)	(127.8)
Other Current Assets	27.4	14.8
Other Current Liabilities	(223.0)	(112.3)
Net Cash Flows from (Used for) Operating Activities	1,800.8	2,006.8
Investing Activities
Construction Expenditures	(2,986.7)	(3,223.4)
Acquisitions of Assets	(581.2)	0.0
Purchases of Investment Securities	(235.5)	(1,069.2)
Sales of Investment Securities	199.5	1,037.8
Acquisitions of Nuclear Fuel	(33.8)	(24.2)
Other Investing Activities	42.7	40.1
Net Cash Flows from (Used for) Investing Activities	(3,595.0)	(3,238.9)
Financing Activities
Issuance of Common Stock, Net	32.3	50.9
Issuance of Long-term Debt	2,773.7	2,209.2
Commercial Paper and Credit Facility Borrowings	0.0	205.6
Change in Short-term Debt, Net	367.0	952.0
Retirement of Long-term Debt	(728.3)	(1,339.8)
Commercial Paper and Credit Facility Repayments	0.0	(207.0)
Make Whole Premium on Extinguishment of Long-term Debt	(3.0)	0.0
Principal Payments for Finance Leases	(29.6)	(33.5)
Dividends Paid on Common Stock	(668.1)	(614.2)
Other Financing Activities	(4.3)	(16.4)
Net Cash Flows from (Used for) Financing Activities	1,739.7	1,206.8
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	(54.5)	(25.3)
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	389.6	387.3
Cash and Cash Equivalents at End of Period	210.5
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	490.2	455.4
Net Cash Paid (Received) for Income Taxes	19.7	33.8
Noncash Acquisitions Under Finance Leases	44.4	32.8
Construction Expenditures Included in Current Liabilities as of June 30,	904.8	940.0
Acquisition of Nuclear Fuel Included in Current Liabilities as of June 30,	50.5	0.6
Noncash Contribution of Assets by Noncontrolling Interest	0.0	84.0
Expected Reimbursement for Spent Nuclear Fuel Dry Cask Storage	0.0	0.7
Noncash or Part Noncash Acquisition, Value of Liabilities Assumed	18.6	0.0
AEP Texas Inc. [Member]
Operating Activities
Net Income (Loss)	115.0	93.3
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	294.6	231.6
Deferred Income Taxes	(59.9)	24.9
Allowance for Equity Funds Used During Construction	(3.2)	(9.4)
Property Taxes	(45.0)	(38.4)
Change in Other Noncurrent Assets	24.4	(36.1)
Change in Other Noncurrent Liabilities	5.6	21.6
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	(46.2)	(67.1)
Fuel, Materials and Supplies	0.8	0.5
Accounts Payable	1.8	(29.6)
Accrued Taxes, Net	26.4	37.5
Other Current Assets	2.0	1.6
Other Current Liabilities	(21.8)	(5.5)
Net Cash Flows from (Used for) Operating Activities	294.5	224.9
Investing Activities
Construction Expenditures	(671.6)	(792.8)
Change in Advances to Affiliates, Net	0.3	84.8
Other Investing Activities	7.6	19.2
Net Cash Flows from (Used for) Investing Activities	(663.7)	(688.8)
Financing Activities
Capital Contributions from Parent	200.0	100.0
Issuance of Long-term Debt	295.6	494.5
Change in Advances from Affiliates, Net	23.0	0.0
Retirement of Long-term Debt	(181.8)	(154.1)
Principal Payments for Finance Leases	(2.5)	(2.3)
Other Financing Activities	0.6	0.6
Net Cash Flows from (Used for) Financing Activities	334.9	438.7
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	(34.3)	(25.2)
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	125.5	132.0
Cash and Cash Equivalents at End of Period	0.1
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	73.4	69.3
Net Cash Paid (Received) for Income Taxes	14.4	(22.4)
Noncash Acquisitions Under Finance Leases	4.4	6.3
Construction Expenditures Included in Current Liabilities as of June 30,	192.9	186.8
AEP Transmission Co [Member]
Operating Activities
Net Income (Loss)	240.3	166.1
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	83.1	62.6
Deferred Income Taxes	19.7	49.9
Allowance for Equity Funds Used During Construction	(40.1)	(30.7)
Property Taxes	68.3	44.7
Long-term Accounts Receivable - Affiliated	(7.8)	(6.2)
Change in Other Noncurrent Assets	3.6	(6.7)
Change in Other Noncurrent Liabilities	(6.4)	17.8
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	(31.7)	8.5
Fuel, Materials and Supplies	1.8	(2.4)
Accounts Payable	6.3	3.4
Accrued Taxes, Net	(43.1)	(29.8)
Accrued Interest	0.4	(3.3)
Other Current Assets	0.0	0.4
Other Current Liabilities	(0.2)	(28.2)
Net Cash Flows from (Used for) Operating Activities	294.2	246.1
Investing Activities
Construction Expenditures	(661.5)	(855.4)
Change in Advances to Affiliates, Net	45.7	92.7
Acquisitions of Assets	(2.6)	(13.1)
Other Investing Activities	4.8	1.1
Net Cash Flows from (Used for) Investing Activities	(613.6)	(774.7)
Financing Activities
Capital Contributions from Parent	0.0	377.0
Issuance of Long-term Debt	344.3	0.0
Change in Advances from Affiliates, Net	(24.9)	151.8
Principal Payments for Finance Leases	0.0
Other Financing Activities	0.0	(0.2)
Net Cash Flows from (Used for) Financing Activities	319.4	528.6
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	41.0	43.1
Net Cash Paid (Received) for Income Taxes	17.4	(20.4)
Construction Expenditures Included in Current Liabilities as of June 30,	278.5	241.1
Appalachian Power Co [Member]
Operating Activities
Net Income (Loss)	189.2	202.9
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	229.6	213.8
Deferred Income Taxes	(73.5)	10.8
Carrying Costs Income	0.0	(1.0)
Allowance for Equity Funds Used During Construction	(7.7)	(5.5)
Mark-to-Market of Risk Management Contracts	(12.9)	(36.1)
Deferred Fuel Over/Under-Recovery, Net	41.4	(73.8)
Change in Other Noncurrent Assets	(1.8)	32.0
Change in Other Noncurrent Liabilities	(31.2)	68.7
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	60.2	4.7
Fuel, Materials and Supplies	(50.2)	20.2
Accounts Payable	23.0	(11.1)
Accrued Taxes, Net	(7.8)	(7.6)
Other Current Assets	17.4	7.1
Other Current Liabilities	(29.8)	(21.9)
Net Cash Flows from (Used for) Operating Activities	345.9	404.2
Investing Activities
Construction Expenditures	(397.1)	(406.8)
Change in Advances to Affiliates, Net	0.3	0.1
Other Investing Activities	20.7	7.8
Net Cash Flows from (Used for) Investing Activities	(376.1)	(398.9)
Financing Activities
Issuance of Long-term Debt	478.3	103.7
Change in Advances from Affiliates, Net	(179.5)	(13.3)
Retirement of Long-term Debt	(168.0)	(11.7)
Principal Payments for Finance Leases	(3.1)	(3.4)
Dividends Paid on Common Stock	(100.0)	(80.0)
Other Financing Activities	0.4	0.7
Net Cash Flows from (Used for) Financing Activities	28.1	(4.0)
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	(2.1)	1.3
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	27.7	20.5
Cash and Cash Equivalents at End of Period	2.3
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	91.6	90.9
Net Cash Paid (Received) for Income Taxes	35.0	19.7
Noncash Acquisitions Under Finance Leases	5.7	2.7
Construction Expenditures Included in Current Liabilities as of June 30,	116.5	89.5
Indiana Michigan Power Co [Member]
Operating Activities
Net Income (Loss)	159.2	158.9
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	173.5	121.9
Deferred Income Taxes	(17.2)	33.1
Deferral of Incremental Nuclear Refueling Outage Expenses, Net	(14.3)	(3.5)
Carrying Costs Income	1.4	(4.0)
Allowance for Equity Funds Used During Construction	(12.5)	(4.1)
Mark-to-Market of Risk Management Contracts	(6.0)	(5.2)
Amortization of Nuclear Fuel	46.1	51.4
Deferred Fuel Over/Under-Recovery, Net	(16.5)	8.1
Change in Other Noncurrent Assets	32.6	(5.6)
Change in Other Noncurrent Liabilities	(3.6)	44.4
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	35.8	(18.3)
Fuel, Materials and Supplies	(3.8)	(5.0)
Accounts Payable	(50.4)	(12.2)
Accrued Taxes, Net	(15.9)	0.8
Other Current Assets	9.6	1.2
Other Current Liabilities	(38.6)	(16.9)
Net Cash Flows from (Used for) Operating Activities	279.4	345.0
Investing Activities
Construction Expenditures	(293.8)	(284.7)
Change in Advances to Affiliates, Net	(0.3)	(79.9)
Purchases of Investment Securities	(226.6)	(1,067.8)
Sales of Investment Securities	199.5	1,037.8
Acquisitions of Nuclear Fuel	(33.8)	(24.2)
Other Investing Activities	9.0	8.2
Net Cash Flows from (Used for) Investing Activities	(346.0)	(410.6)
Financing Activities
Issuance of Long-term Debt	62.8	700.6
Change in Advances from Affiliates, Net	93.6	(211.6)
Retirement of Long-term Debt	(48.3)	(352.4)
Principal Payments for Finance Leases	(2.7)	(5.2)
Dividends Paid on Common Stock	(40.0)	(67.0)
Other Financing Activities	0.2	1.3
Net Cash Flows from (Used for) Financing Activities	65.6	65.7
Net Increase (Decrease) in Cash and Cash Equivalents	(1.0)	0.1
Cash and Cash Equivalents at Beginning of Period	2.4	1.3
Cash and Cash Equivalents at End of Period	1.4	1.4
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	55.2	55.2
Net Cash Paid (Received) for Income Taxes	27.9	(23.6)
Noncash Acquisitions Under Finance Leases	4.5	3.2
Construction Expenditures Included in Current Liabilities as of June 30,	77.7	86.5
Acquisition of Nuclear Fuel Included in Current Liabilities as of June 30,	50.5	0.6
Expected Reimbursement for Spent Nuclear Fuel Dry Cask Storage	0.0	0.7
Ohio Power Co [Member]
Operating Activities
Net Income (Loss)	178.6	148.4
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	119.4	129.9
Amortization Of Generation Deferrals	56.5	115.0
Deferred Income Taxes	9.4	(12.5)
Carrying Costs Income	(0.4)	(1.3)
Allowance for Equity Funds Used During Construction	(9.3)	(5.8)
Mark-to-Market of Risk Management Contracts	12.1	(45.5)
Property Taxes	130.1	129.6
Refund of Global Settlement	(8.2)	(5.5)
Reversal of a Regulatory Provision	(56.2)	0.0
Change in Other Noncurrent Assets	(30.1)	83.3
Change in Other Noncurrent Liabilities	(38.0)	56.0
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	70.0	14.0
Fuel, Materials and Supplies	(8.5)	(3.6)
Accounts Payable	(34.9)	(39.9)
Accrued Taxes, Net	(169.4)	(169.5)
Other Current Assets	(4.2)	(0.6)
Other Current Liabilities	2.6	(11.4)
Net Cash Flows from (Used for) Operating Activities	219.5	380.6
Investing Activities
Construction Expenditures	(385.5)	(312.8)
Change in Advances to Affiliates, Net	(63.9)	0.0
Other Investing Activities	7.5	12.7
Net Cash Flows from (Used for) Investing Activities	(441.9)	(300.1)
Financing Activities
Issuance of Long-term Debt	444.3	392.9
Change in Advances from Affiliates, Net	(114.1)	126.1
Retirement of Long-term Debt	(23.4)	(372.9)
Principal Payments for Finance Leases	(1.8)	(1.9)
Dividends Paid on Common Stock	(85.0)	(225.0)
Other Financing Activities	0.8	0.4
Net Cash Flows from (Used for) Financing Activities	220.8	(80.4)
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	(1.6)	0.1
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	30.9	29.8
Cash and Cash Equivalents at End of Period	2.7
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	46.1	48.3
Net Cash Paid (Received) for Income Taxes	14.3	45.1
Noncash Acquisitions Under Finance Leases	6.1	1.9
Construction Expenditures Included in Current Liabilities as of June 30,	77.9	64.5
Public Service Co Of Oklahoma [Member]
Operating Activities
Net Income (Loss)	48.1	29.4
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	86.3	78.2
Deferred Income Taxes	(9.0)	(6.5)
Allowance for Equity Funds Used During Construction	(0.7)	0.1
Mark-to-Market of Risk Management Contracts	(18.3)	(18.1)
Property Taxes	(19.2)	(19.2)
Deferred Fuel Over/Under-Recovery, Net	9.0	29.9
Change in Other Noncurrent Assets	4.6	1.4
Change in Other Noncurrent Liabilities	(2.4)	14.8
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	(12.6)	(6.4)
Fuel, Materials and Supplies	0.4	(0.8)
Accounts Payable	28.5	23.0
Accrued Taxes, Net	12.8	30.0
Other Current Assets	(1.6)	0.5
Other Current Liabilities	3.3	3.0
Net Cash Flows from (Used for) Operating Activities	129.2	159.3
Investing Activities
Construction Expenditures	(132.7)	(104.2)
Other Investing Activities	1.1	2.7
Net Cash Flows from (Used for) Investing Activities	(131.6)	(101.5)
Financing Activities
Issuance of Long-term Debt	349.9	0.0
Change in Advances from Affiliates, Net	(82.9)	(31.2)
Retirement of Long-term Debt	(250.2)	(0.2)
Principal Payments for Finance Leases	(1.5)	(1.8)
Dividends Paid on Common Stock	(11.3)	(25.0)
Other Financing Activities	(2.2)	0.4
Net Cash Flows from (Used for) Financing Activities	1.8	(57.8)
Net Increase (Decrease) in Cash and Cash Equivalents	(0.6)	0.0
Cash and Cash Equivalents at Beginning of Period	2.0	1.6
Cash and Cash Equivalents at End of Period	1.4	1.6
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	30.9	31.7
Net Cash Paid (Received) for Income Taxes	11.1	(1.8)
Noncash Acquisitions Under Finance Leases	2.3	1.8
Construction Expenditures Included in Current Liabilities as of June 30,	19.7	25.9
Southwestern Electric Power Co [Member]
Operating Activities
Net Income (Loss)	36.3	52.1
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	123.9	116.0
Deferred Income Taxes	(10.1)	0.4
Allowance for Equity Funds Used During Construction	(2.9)	(3.2)
Mark-to-Market of Risk Management Contracts	(6.2)	1.1
Property Taxes	(32.2)	(31.6)
Deferred Fuel Over/Under-Recovery, Net	8.2	0.8
Provision for Refund	(25.2)	0.0
Change in Other Noncurrent Assets	2.9	(7.6)
Change in Other Noncurrent Liabilities	2.0	45.4
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	(26.1)	22.1
Fuel, Materials and Supplies	(19.3)	1.2
Accounts Payable	5.5	(17.3)
Accrued Taxes, Net	47.7	31.8
Other Current Assets	(1.4)	4.5
Other Current Liabilities	23.4	10.5
Net Cash Flows from (Used for) Operating Activities	151.7	226.2
Investing Activities
Construction Expenditures	(185.2)	(244.6)
Change in Advances to Affiliates, Net	81.4	0.0
Other Investing Activities	(2.2)	0.6
Net Cash Flows from (Used for) Investing Activities	(106.0)	(244.0)
Financing Activities
Issuance of Long-term Debt	0.0	444.6
Change in Short-term Debt, Net	0.0	3.2
Change in Advances from Affiliates, Net	55.3	1.2
Retirement of Long-term Debt	(56.6)	(383.5)
Principal Payments for Finance Leases	(5.5)	(5.7)
Dividends Paid on Common Stock	(37.5)	(40.0)
Dividends Paid on Common Stock	(2.2)	(1.8)
Other Financing Activities	0.3	0.3
Net Cash Flows from (Used for) Financing Activities	(46.2)	18.3
Net Increase (Decrease) in Cash and Cash Equivalents	(0.5)	0.5
Cash and Cash Equivalents at Beginning of Period	24.5	1.6
Cash and Cash Equivalents at End of Period	24.0	2.1
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	57.1	59.7
Net Cash Paid (Received) for Income Taxes	6.2	16.3
Noncash Acquisitions Under Finance Leases	2.6	2.7
Construction Expenditures Included in Current Liabilities as of June 30,	40.9	39.5
AEP Wind Holdings LLC [Member] | Indiana Michigan Power Co [Member]
Supplementary Information
Noncash or Part Noncash Acquisition, Value of Liabilities Assumed	12.9
Noncontrolling Interest [Member] | AEP Wind Holdings LLC [Member]
Supplementary Information
Noncash Contribution of Assets by Noncontrolling Interest	134.8	$ 0.0
Liabilities, Total [Member] | AEP Wind Holdings LLC [Member]
Supplementary Information
Noncash or Part Noncash Acquisition, Value of Liabilities Assumed	$ 18.6