Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Operating Activities
Net Income (Loss)	$ 986.8	$ 970.4
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	1,092.9	967.4
Deferred Income Taxes	149.7	424.1
Carrying Costs Income	(6.3)	(11.6)
Allowance for Equity Funds Used During Construction	(61.5)	(42.2)
Mark-to-Market of Risk Management Contracts	(112.9)	(84.7)
Amortization of Nuclear Fuel	51.4	71.6
Pension Contributions to Qualified Plan Trust	0.0	(93.3)
Property Taxes	119.9	122.9
Deferred Fuel Over/Under-Recovery, Net	12.3	20.7
Gain on Sale of Merchant Generation Assets	0.0	(226.4)
Recovery of Ohio Capacity Costs, Net	35.8	47.1
Provision for Refund - Global Settlement	(5.5)	(88.1)
Change in Other Noncurrent Assets	10.4	(188.0)
Change in Other Noncurrent Liabilities	185.1	132.0
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	(209.9)	270.5
Fuel, Materials and Supplies	31.2	(9.5)
Accounts Payable	(53.6)	(170.5)
Accrued Taxes, Net	(127.8)	(72.8)
Other Current Assets	14.8	(45.3)
Other Current Liabilities	(112.3)	(288.9)
Net Cash Flows from (Used for) Operating Activities	2,006.8	1,717.0
Investing Activities
Construction Expenditures	(3,223.4)	(2,510.4)
Purchases of Investment Securities	(1,069.2)	(1,318.2)
Sales of Investment Securities	1,037.8	1,289.1
Acquisitions of Nuclear Fuel	(24.2)	(38.9)
Proceeds From Sale Of Merchant Generation Assets	0.0	2,159.6
Other Investing Activities	40.1	22.0
Net Cash Flows from (Used for) Investing Activities	(3,238.9)	(396.8)
Financing Activities
Issuance of Common Stock, Net	50.9	0.0
Issuance of Long-term Debt	2,209.2	1,050.0
Commercial Paper and Credit Facility Borrowings	205.6	0.0
Change in Short-term Debt, Net	952.0	138.7
Retirement of Long-term Debt	(1,339.8)	(1,899.3)
Commercial Paper and Credit Facility Repayments	(207.0)	0.0
Make Whole Premium on Extinguishment of Long-term Debt	0.0	(44.9)
Principal Payments for Capital Lease Obligations	(33.5)	(33.3)
Dividends Paid on Common Stock	(614.2)	(584.9)
Other Financing Activities	(16.4)	(5.7)
Net Cash Flows from (Used for) Financing Activities	1,206.8	(1,379.4)
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	(25.3)	(59.2)
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	412.6	403.5
Cash and Cash Equivalents at Beginning of Period	214.6
Cash, Cash Equivalents and Restricted Cash at End of Period	387.3	344.3
Cash and Cash Equivalents at End of Period	211.2
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	455.4	442.3
Net Cash Paid (Received) for Income Taxes	33.8	(21.2)
Noncash Acquisitions Under Capital Leases	32.8	23.6
Construction Expenditures Included in Current Liabilities as of June 30,	940.0	597.9
Construction Expenditures Included in Noncurrent Liabilities as of June 30,	0.0	71.8
Acquisition of Nuclear Fuel Included in Current Liabilities as of June 30,	0.6	26.0
Noncash Contribution of Assets by Noncontrolling Interest	84.0	0.0
Expected Reimbursement for Spent Nuclear Fuel Dry Cask Storage	0.7	2.4
AEP Texas Inc. [Member]
Operating Activities
Net Income (Loss)	93.3	82.3
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	231.6	219.0
Deferred Income Taxes	24.9	71.8
Allowance for Equity Funds Used During Construction	(9.4)	(2.2)
Mark-to-Market of Risk Management Contracts	0.0	0.3
Pension Contributions to Qualified Plan Trust	0.0	(8.8)
Property Taxes	(38.4)	(32.7)
Change in Other Noncurrent Assets	(36.1)	(20.4)
Change in Other Noncurrent Liabilities	21.6	5.9
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	(67.1)	(38.0)
Fuel, Materials and Supplies	0.5	4.8
Accounts Payable	(29.6)	(4.5)
Accrued Taxes, Net	37.5	(4.3)
Other Current Assets	1.6	1.4
Other Current Liabilities	(5.5)	(31.0)
Net Cash Flows from (Used for) Operating Activities	224.9	243.6
Investing Activities
Construction Expenditures	(792.8)	(378.5)
Change in Advances to Affiliates, Net	84.8	0.3
Other Investing Activities	19.2	6.9
Net Cash Flows from (Used for) Investing Activities	(688.8)	(371.3)
Financing Activities
Capital Contributions from Parent	100.0	200.0
Issuance of Long-term Debt	494.5	0.0
Change in Advances from Affiliates, Net	0.0	28.2
Retirement of Long-term Debt	(154.1)	(117.1)
Principal Payments for Capital Lease Obligations	(2.3)	(1.9)
Other Financing Activities	0.6	0.8
Net Cash Flows from (Used for) Financing Activities	438.7	110.0
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	(25.2)	(17.7)
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	157.2	146.9
Cash and Cash Equivalents at Beginning of Period	2.0
Cash, Cash Equivalents and Restricted Cash at End of Period	132.0	129.2
Cash and Cash Equivalents at End of Period	0.1
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	69.3	69.4
Net Cash Paid (Received) for Income Taxes	(22.4)	1.5
Noncash Acquisitions Under Capital Leases	6.3	2.9
Construction Expenditures Included in Current Liabilities as of June 30,	186.8	95.2
AEP Transmission Co [Member]
Operating Activities
Net Income (Loss)	156.4	164.4
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	63.0	46.1
Deferred Income Taxes	50.2	134.0
Allowance for Equity Funds Used During Construction	(31.6)	(24.3)
Property Taxes	44.7	44.1
Long-term Accounts Receivable - Affiliated	(6.2)	(27.6)
Change in Other Noncurrent Assets	(7.0)	(8.8)
Change in Other Noncurrent Liabilities	17.8	17.0
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	8.4	(37.0)
Fuel, Materials and Supplies	(2.4)	(5.9)
Accounts Payable	13.7	(2.7)
Accrued Taxes, Net	(29.8)	(27.1)
Accrued Interest	(3.3)	(0.7)
Other Current Assets	0.4	(4.7)
Other Current Liabilities	(28.2)	1.0
Net Cash Flows from (Used for) Operating Activities	246.1	267.8
Investing Activities
Construction Expenditures	(855.4)	(721.2)
Change in Advances to Affiliates, Net	92.7	44.9
Acquisitions of Assets	(13.1)	0.0
Other Investing Activities	1.1	(0.5)
Net Cash Flows from (Used for) Investing Activities	(774.7)	(676.8)
Financing Activities
Capital Contributions from Parent	377.0	166.7
Change in Advances from Affiliates, Net	151.8	243.3
Other Financing Activities	(0.2)	(1.0)
Net Cash Flows from (Used for) Financing Activities	528.6	409.0
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	42.7	31.4
Net Cash Paid (Received) for Income Taxes	(20.4)	(67.0)
Construction Expenditures Included in Current Liabilities as of June 30,	234.7	190.3
Appalachian Power Co [Member]
Operating Activities
Net Income (Loss)	202.9	162.7
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	213.8	201.3
Deferred Income Taxes	10.8	86.2
Carrying Costs Income	(1.0)	(0.6)
Allowance for Equity Funds Used During Construction	(5.5)	(3.5)
Mark-to-Market of Risk Management Contracts	(36.1)	(39.4)
Pension Contributions to Qualified Plan Trust	0.0	(10.2)
Deferred Fuel Over/Under-Recovery, Net	(73.8)	(4.0)
Change in Other Noncurrent Assets	32.0	15.5
Change in Other Noncurrent Liabilities	68.7	13.7
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	4.7	24.0
Fuel, Materials and Supplies	20.2	0.3
Accounts Payable	(11.1)	18.7
Accrued Taxes, Net	(7.6)	(35.8)
Other Current Assets	7.1	8.5
Other Current Liabilities	(21.9)	(14.1)
Net Cash Flows from (Used for) Operating Activities	404.2	423.9
Investing Activities
Construction Expenditures	(406.8)	(372.2)
Change in Advances to Affiliates, Net	0.1	0.3
Other Investing Activities	7.8	10.5
Net Cash Flows from (Used for) Investing Activities	(398.9)	(361.4)
Financing Activities
Issuance of Long-term Debt	103.7	320.9
Change in Advances from Affiliates, Net	(13.3)	45.1
Retirement of Long-term Debt	(11.7)	(365.9)
Principal Payments for Capital Lease Obligations	(3.4)	(3.5)
Dividends Paid on Common Stock	(80.0)	(60.0)
Other Financing Activities	0.7	0.4
Net Cash Flows from (Used for) Financing Activities	(4.0)	(63.0)
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	1.3	(0.5)
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	19.2	18.5
Cash and Cash Equivalents at Beginning of Period	2.9
Cash, Cash Equivalents and Restricted Cash at End of Period	20.5	18.0
Cash and Cash Equivalents at End of Period	2.8
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	90.9	92.4
Net Cash Paid (Received) for Income Taxes	19.7	32.0
Noncash Acquisitions Under Capital Leases	2.7	1.7
Construction Expenditures Included in Current Liabilities as of June 30,	89.5	99.1
Indiana Michigan Power Co [Member]
Operating Activities
Net Income (Loss)	158.9	78.9
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	121.9	99.8
Deferred Income Taxes	33.1	74.4
Deferral of Incremental Nuclear Refueling Outage Expenses, Net	(3.5)	31.6
Carrying Costs Income	(4.0)	(7.7)
Allowance for Equity Funds Used During Construction	(4.1)	(4.6)
Mark-to-Market of Risk Management Contracts	(5.2)	(12.3)
Amortization of Nuclear Fuel	51.4	71.6
Pension Contributions to Qualified Plan Trust	0.0	(13.0)
Deferred Fuel Over/Under-Recovery, Net	8.1	25.3
Change in Other Noncurrent Assets	(5.6)	(18.7)
Change in Other Noncurrent Liabilities	44.4	34.8
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	(18.3)	33.5
Fuel, Materials and Supplies	(5.0)	(15.2)
Accounts Payable	(12.2)	9.0
Customer Deposits	(0.1)	2.3
Accrued Taxes, Net	0.8	13.0
Accrued Interest	2.5	0.1
Other Current Assets	1.2	15.9
Other Current Liabilities	(19.3)	(29.5)
Net Cash Flows from (Used for) Operating Activities	345.0	389.2
Investing Activities
Construction Expenditures	(284.7)	(304.4)
Change in Advances to Affiliates, Net	(79.9)	(0.1)
Purchases of Investment Securities	(1,067.8)	(1,317.2)
Sales of Investment Securities	1,037.8	1,289.1
Acquisitions of Nuclear Fuel	(24.2)	(38.9)
Other Investing Activities	8.2	3.4
Net Cash Flows from (Used for) Investing Activities	(410.6)	(368.1)
Financing Activities
Issuance of Long-term Debt	700.6	411.5
Change in Advances from Affiliates, Net	(211.6)	(171.8)
Retirement of Long-term Debt	(352.4)	(193.3)
Principal Payments for Capital Lease Obligations	(5.2)	(5.9)
Dividends Paid on Common Stock	(67.0)	(62.5)
Other Financing Activities	1.3	0.8
Net Cash Flows from (Used for) Financing Activities	65.7	(21.2)
Net Increase (Decrease) in Cash and Cash Equivalents	0.1	(0.1)
Cash and Cash Equivalents at Beginning of Period	1.3	1.2
Cash and Cash Equivalents at End of Period	1.4	1.1
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	55.2	49.2
Net Cash Paid (Received) for Income Taxes	(23.6)	(56.9)
Noncash Acquisitions Under Capital Leases	3.2	2.6
Construction Expenditures Included in Current Liabilities as of June 30,	86.5	96.0
Acquisition of Nuclear Fuel Included in Current Liabilities as of June 30,	0.6	26.0
Expected Reimbursement for Spent Nuclear Fuel Dry Cask Storage	0.7	2.5
Ohio Power Co [Member]
Operating Activities
Net Income (Loss)	148.4	148.5
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	129.9	108.4
Amortization Of Generation Deferrals	115.0	114.2
Deferred Income Taxes	(12.5)	94.5
Carrying Costs Income	(1.3)	(2.5)
Allowance for Equity Funds Used During Construction	(5.8)	(3.2)
Mark-to-Market of Risk Management Contracts	(45.5)	11.8
Pension Contributions to Qualified Plan Trust	0.0	(8.2)
Property Taxes	129.6	117.2
Provision for Refund - Global Settlement	(5.5)	(88.1)
Change in Other Noncurrent Assets	83.3	(93.1)
Change in Other Noncurrent Liabilities	56.0	41.8
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	14.0	18.3
Fuel, Materials and Supplies	(3.6)	(7.4)
Accounts Payable	(39.9)	(6.8)
Accrued Taxes, Net	(169.5)	(252.5)
Other Current Assets	(0.6)	(9.6)
Other Current Liabilities	(11.4)	(25.3)
Net Cash Flows from (Used for) Operating Activities	380.6	158.0
Investing Activities
Construction Expenditures	(312.8)	(224.5)
Change in Advances to Affiliates, Net	0.0	24.2
Other Investing Activities	12.7	4.9
Net Cash Flows from (Used for) Investing Activities	(300.1)	(195.4)
Financing Activities
Issuance of Long-term Debt	392.9	0.0
Change in Advances from Affiliates, Net	126.1	190.5
Retirement of Long-term Debt	(372.9)	(22.5)
Principal Payments for Capital Lease Obligations	(1.9)	(2.0)
Dividends Paid on Common Stock	(225.0)	(130.0)
Other Financing Activities	0.4	0.6
Net Cash Flows from (Used for) Financing Activities	(80.4)	36.6
Net Increase (Decrease) in Cash, Cash Equivalents and Restricted Cash	0.1	(0.8)
Cash, Cash Equivalents and Restricted Cash at Beginning of Period	29.7	30.3
Cash and Cash Equivalents at Beginning of Period	3.1
Cash, Cash Equivalents and Restricted Cash at End of Period	29.8	29.5
Cash and Cash Equivalents at End of Period	3.3
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	48.3	50.0
Net Cash Paid (Received) for Income Taxes	45.1	76.8
Noncash Acquisitions Under Capital Leases	1.9	1.9
Construction Expenditures Included in Current Liabilities as of June 30,	64.5	50.3
Public Service Co Of Oklahoma [Member]
Operating Activities
Net Income (Loss)	29.4	25.2
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	78.2	66.1
Deferred Income Taxes	(6.5)	53.7
Allowance for Equity Funds Used During Construction	0.1	(0.4)
Mark-to-Market of Risk Management Contracts	(18.1)	(8.7)
Pension Contributions to Qualified Plan Trust	0.0	(5.3)
Property Taxes	(19.2)	(18.9)
Deferred Fuel Over/Under-Recovery, Net	29.9	(29.6)
Change in Other Noncurrent Assets	1.4	(18.6)
Change in Other Noncurrent Liabilities	14.8	(0.7)
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	(6.4)	5.6
Fuel, Materials and Supplies	(0.8)	8.2
Accounts Payable	23.0	9.0
Accrued Taxes, Net	30.0	24.0
Other Current Assets	0.5	(1.2)
Other Current Liabilities	3.0	(26.0)
Net Cash Flows from (Used for) Operating Activities	159.3	82.4
Investing Activities
Construction Expenditures	(104.2)	(136.2)
Other Investing Activities	2.7	1.3
Net Cash Flows from (Used for) Investing Activities	(101.5)	(134.9)
Financing Activities
Change in Advances from Affiliates, Net	(31.2)	89.4
Retirement of Long-term Debt	(0.2)	(0.2)
Principal Payments for Capital Lease Obligations	(1.8)	(2.0)
Dividends Paid on Common Stock	(25.0)	(35.0)
Other Financing Activities	0.4	0.2
Net Cash Flows from (Used for) Financing Activities	(57.8)	52.4
Net Increase (Decrease) in Cash and Cash Equivalents	0.0	(0.1)
Cash and Cash Equivalents at Beginning of Period	1.6	1.5
Cash and Cash Equivalents at End of Period	1.6	1.4
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	31.7	31.7
Net Cash Paid (Received) for Income Taxes	(1.8)	(42.9)
Noncash Acquisitions Under Capital Leases	1.8	0.9
Construction Expenditures Included in Current Liabilities as of June 30,	25.9	29.2
Southwestern Electric Power Co [Member]
Operating Activities
Net Income (Loss)	52.1	42.4
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	116.0	102.9
Deferred Income Taxes	0.4	68.7
Allowance for Equity Funds Used During Construction	(3.2)	(0.8)
Mark-to-Market of Risk Management Contracts	1.1	(11.4)
Pension Contributions to Qualified Plan Trust	0.0	(8.9)
Property Taxes	(31.6)	(30.8)
Deferred Fuel Over/Under-Recovery, Net	0.8	(3.1)
Change in Other Noncurrent Assets	(7.6)	(3.3)
Change in Other Noncurrent Liabilities	45.4	(11.1)
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	22.1	22.0
Fuel, Materials and Supplies	1.2	3.1
Accounts Payable	(17.3)	13.2
Accrued Taxes, Net	31.8	48.8
Other Current Assets	4.5	9.3
Other Current Liabilities	10.5	(24.1)
Net Cash Flows from (Used for) Operating Activities	226.2	216.9
Investing Activities
Construction Expenditures	(244.6)	(164.7)
Change in Advances to Affiliates, Net	0.0	167.8
Other Investing Activities	0.6	3.3
Net Cash Flows from (Used for) Investing Activities	(244.0)	6.4
Financing Activities
Issuance of Long-term Debt	444.6	114.7
Change in Short-term Debt, Net	3.2	8.7
Change in Advances from Affiliates, Net	1.2	58.6
Retirement of Long-term Debt	(383.5)	(351.8)
Principal Payments for Capital Lease Obligations	(5.7)	(5.7)
Dividends Paid on Common Stock	(40.0)	(55.0)
Dividends Paid on Common Stock	(1.8)	(1.7)
Other Financing Activities	0.3	0.3
Net Cash Flows from (Used for) Financing Activities	18.3	(231.9)
Net Increase (Decrease) in Cash and Cash Equivalents	0.5	(8.6)
Cash and Cash Equivalents at Beginning of Period	1.6	10.3
Cash and Cash Equivalents at End of Period	2.1	1.7
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	59.7	66.8
Net Cash Paid (Received) for Income Taxes	16.3	(56.5)
Noncash Acquisitions Under Capital Leases	2.7	1.8
Construction Expenditures Included in Current Liabilities as of June 30,	$ 39.5	$ 50.6