Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Operating Activities
Net Income (Loss)	$ 970.4	$ 1,007.0
Income (Loss) from Discontinued Operations	0.0	(2.5)
Income (Loss) from Continuing Operations, Including Portion Attributable to Noncontrolling Interest	970.4	1,009.5
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	967.4	1,010.9
Deferred Income Taxes	424.1	552.3
Asset Impairments and Other Related Charges	13.1	0.0
Carrying Costs Income	(11.6)	(10.2)
Allowance for Equity Funds Used During Construction	(42.2)	(60.5)
Mark-to-Market of Risk Management Contracts	(84.7)	48.7
Amortization of Nuclear Fuel	71.6	73.2
Pension Contributions to Qualified Plan Trust	(93.3)	(84.8)
Property Taxes	122.9	131.3
Deferred Fuel Over/Under-Recovery, Net	20.7	(5.8)
Gain on Sale of Merchant Generation Assets	(226.4)	0.0
Recovery of Ohio Capacity Costs, Net	47.1	67.4
Provision for Refund - Global Settlement	(88.1)	0.0
Change in Other Noncurrent Assets	(201.1)	(201.2)
Change in Other Noncurrent Liabilities	132.0	1.8
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	270.5	(166.0)
Fuel, Materials and Supplies	(9.5)	(107.0)
Accounts Payable	(170.5)	(22.6)
Accrued Taxes, Net	(72.8)	(303.7)
Other Current Assets	(45.3)	26.3
Other Current Liabilities	(288.9)	(244.0)
Net Cash Flows from (Used for) Operating Activities	1,717.0	1,725.8
Construction Expenditures	(2,510.4)	(2,285.8)
Change in Other Temporary Investments, Net	13.5	80.9
Purchases of Investment Securities	(1,318.2)	(1,797.4)
Sales of Investment Securities	1,289.1	1,777.0
Acquisitions of Nuclear Fuel	(38.9)	(79.2)
Proceeds from Sale of Merchant Generation Assets	2,159.6	0.0
Other Investing Activities	29.6	4.8
Net Cash Flows from (Used for) Investing Activities	(375.7)	(2,299.7)
Financing Activities
Issuance of Common Stock, Net	0.0	30.9
Issuance of Long-term Debt	1,050.0	743.4
Change in Short-term Debt, Net	138.7	1,260.3
Retirement of Long-term Debt	(1,899.3)	(784.1)
Make Whole Premium on Extinguishment of Long-term Debt	(44.9)	0.0
Principal Payments for Capital Lease Obligations	(33.3)	(51.0)
Dividends Paid on Common Stock	(584.9)	(553.1)
Other Financing Activities	(5.7)	0.4
Net Cash Flows from (Used for) Financing Activities	(1,379.4)	646.8
Cash Flows from Discontinued Operations
Operating Activities	0.0	(2.5)
Investing Activities	0.0	0.0
Financing Activities	0.0	0.0
Net Increase (Decrease) in Cash and Cash Equivalents	(38.1)	70.4
Cash and Cash Equivalents at Beginning of Period	210.5	176.4
Cash and Cash Equivalents at End of Period	172.4	246.8
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	442.3	425.4
Net Cash Paid (Received) for Income Taxes	(21.2)	26.2
Noncash Acquisitions Under Capital Leases	23.6	52.7
Construction Expenditures Included in Current Liabilities as of June 30,	597.9	554.2
Construction Expenditures Included in Noncurrent Liabilities as of June 30,	71.8	0.0
Acquisition of Nuclear Fuel Included in Current Liabilities as of June 30,	26.0	41.5
Expected Reimbursement for Spent Nuclear Fuel Dry Cask Storage	2.4	0.0
AEP Transmission Co [Member]
Operating Activities
Net Income (Loss)	164.4	100.6
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	46.1	30.7
Deferred Income Taxes	134.0	107.1
Allowance for Equity Funds Used During Construction	(24.3)	(26.4)
Property Taxes	44.1	40.8
Long-term Accounts Receivable - Affiliated	(27.6)	0.0
Change in Other Noncurrent Assets	(8.8)	(7.1)
Change in Other Noncurrent Liabilities	17.0	0.4
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	(37.0)	(38.1)
Fuel, Materials and Supplies	(5.9)	0.0
Accounts Payable	(2.7)	(8.4)
Accrued Taxes, Net	(27.1)	80.7
Accrued Interest	(0.7)	0.3
Other Current Assets	(4.7)	0.0
Other Current Liabilities	1.0	0.0
Net Cash Flows from (Used for) Operating Activities	267.8	280.6
Construction Expenditures	(721.2)	(527.4)
Change in Advances to Affiliates, Net	44.9	88.3
Other Investing Activities	(0.5)	(0.4)
Net Cash Flows from (Used for) Investing Activities	(676.8)	(439.5)
Financing Activities
Capital Contributions from Member	166.7	66.9
Change in Advances from Affiliates, Net	243.3	92.0
Other Financing Activities	(1.0)	0.0
Net Cash Flows from (Used for) Financing Activities	409.0	158.9
Cash Flows from Discontinued Operations
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	31.4	20.3
Net Cash Paid (Received) for Income Taxes	(67.0)	(178.0)
Construction Expenditures Included in Current Liabilities as of June 30,	190.3	155.0
Appalachian Power Co [Member]
Operating Activities
Net Income (Loss)	162.7	199.7
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	201.3	191.9
Deferred Income Taxes	86.2	68.3
Carrying Costs Income	(0.6)	(0.2)
Allowance for Equity Funds Used During Construction	(3.5)	(4.6)
Mark-to-Market of Risk Management Contracts	(39.4)	24.2
Pension Contributions to Qualified Plan Trust	(10.2)	(8.8)
Deferred Fuel Over/Under-Recovery, Net	(4.0)	3.8
Change in Other Noncurrent Assets	16.1	(8.2)
Change in Other Noncurrent Liabilities	13.7	(16.3)
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	24.0	(16.7)
Fuel, Materials and Supplies	0.3	(31.7)
Accounts Payable	18.7	(13.5)
Accrued Taxes, Net	(35.8)	7.8
Other Current Assets	8.5	3.5
Other Current Liabilities	(14.1)	(9.5)
Net Cash Flows from (Used for) Operating Activities	423.9	389.7
Construction Expenditures	(372.2)	(322.3)
Change in Advances to Affiliates, Net	0.3	1.0
Other Investing Activities	10.9	9.5
Net Cash Flows from (Used for) Investing Activities	(361.0)	(311.8)
Financing Activities
Issuance of Long-term Debt	320.9	249.2
Change in Advances from Affiliates, Net	45.1	(35.1)
Retirement of Long-term Debt	(365.9)	(136.5)
Principal Payments for Capital Lease Obligations	(3.5)	(3.1)
Dividends Paid on Common Stock	(60.0)	(150.0)
Other Financing Activities	0.4	0.2
Net Cash Flows from (Used for) Financing Activities	(63.0)	(75.3)
Cash Flows from Discontinued Operations
Net Increase (Decrease) in Cash and Cash Equivalents	(0.1)	2.6
Cash and Cash Equivalents at Beginning of Period	2.7	2.8
Cash and Cash Equivalents at End of Period	2.6	5.4
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	92.4	90.9
Net Cash Paid (Received) for Income Taxes	32.0	28.3
Noncash Acquisitions Under Capital Leases	1.7	0.8
Construction Expenditures Included in Current Liabilities as of June 30,	99.1	69.1
Indiana Michigan Power Co [Member]
Operating Activities
Net Income (Loss)	78.9	126.0
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	99.8	94.1
Deferred Income Taxes	74.4	86.8
Amortization (Deferral) of Incremental Nuclear Refueling Outage Expenses, Net	31.6	(20.6)
Allowance for Equity Funds Used During Construction	(4.6)	(6.8)
Mark-to-Market of Risk Management Contracts	(12.3)	3.1
Amortization of Nuclear Fuel	71.6	73.2
Pension Contributions to Qualified Plan Trust	(13.0)	(12.7)
Deferred Fuel Over/Under-Recovery, Net	25.3	4.9
Change in Other Noncurrent Assets	(26.4)	(1.9)
Change in Other Noncurrent Liabilities	34.8	17.9
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	33.5	(6.0)
Fuel, Materials and Supplies	(15.2)	(19.3)
Accounts Payable	9.0	(26.8)
Accrued Taxes, Net	13.0	(9.2)
Other Current Assets	15.9	8.0
Other Current Liabilities	(27.1)	(19.7)
Net Cash Flows from (Used for) Operating Activities	389.2	291.0
Construction Expenditures	(304.4)	(258.9)
Change in Advances to Affiliates, Net	(0.1)	(0.7)
Purchases of Investment Securities	(1,317.2)	(1,796.4)
Sales of Investment Securities	1,289.1	1,777.0
Acquisitions of Nuclear Fuel	(38.9)	(79.2)
Other Investing Activities	3.4	4.0
Net Cash Flows from (Used for) Investing Activities	(368.1)	(354.2)
Financing Activities
Issuance of Long-term Debt	411.5	482.7
Change in Advances from Affiliates, Net	(171.8)	(282.9)
Retirement of Long-term Debt	(193.3)	(53.5)
Principal Payments for Capital Lease Obligations	(5.9)	(19.8)
Dividends Paid on Common Stock	(62.5)	(62.5)
Other Financing Activities	0.8	0.6
Net Cash Flows from (Used for) Financing Activities	(21.2)	64.6
Cash Flows from Discontinued Operations
Net Increase (Decrease) in Cash and Cash Equivalents	(0.1)	1.4
Cash and Cash Equivalents at Beginning of Period	1.2	1.1
Cash and Cash Equivalents at End of Period	1.1	2.5
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	49.2	40.3
Net Cash Paid (Received) for Income Taxes	(56.9)	(23.6)
Noncash Acquisitions Under Capital Leases	2.6	16.5
Construction Expenditures Included in Current Liabilities as of June 30,	96.0	89.8
Acquisition of Nuclear Fuel Included in Current Liabilities as of June 30,	26.0	41.5
Expected Reimbursement for Spent Nuclear Fuel Dry Cask Storage	2.5	0.1
Ohio Power Co [Member]
Operating Activities
Net Income (Loss)	148.5	144.8
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	108.4	119.6
Amortization Of Generation Deferrals	114.2	106.9
Deferred Income Taxes	94.5	20.6
Carrying Costs Income	(2.5)	(3.1)
Allowance for Equity Funds Used During Construction	(3.2)	(3.4)
Mark-to-Market of Risk Management Contracts	11.8	30.2
Pension Contributions to Qualified Plan Trust	(8.2)	(7.1)
Property Taxes	117.2	113.2
Provision for Refund - Global Settlement	(88.1)	0.0
Change in Other Noncurrent Assets	(93.1)	(36.2)
Change in Other Noncurrent Liabilities	41.8	8.6
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	18.3	8.6
Fuel, Materials and Supplies	(7.4)	(3.0)
Accounts Payable	(6.8)	(4.8)
Accrued Taxes, Net	(252.5)	(226.8)
Other Current Assets	(9.6)	(3.4)
Other Current Liabilities	(25.3)	(58.9)
Net Cash Flows from (Used for) Operating Activities	158.0	205.8
Construction Expenditures	(224.5)	(193.2)
Change in Restricted Cash for Securitized Funding	(0.1)	0.5
Change in Advances to Affiliates, Net	24.2	331.1
Other Investing Activities	4.9	6.2
Net Cash Flows from (Used for) Investing Activities	(195.5)	144.6
Financing Activities
Change in Advances from Affiliates, Net	190.5	177.1
Retirement of Long-term Debt	(22.5)	(372.8)
Principal Payments for Capital Lease Obligations	(2.0)	(2.0)
Dividends Paid on Common Stock	(130.0)	(150.0)
Other Financing Activities	0.6	0.5
Net Cash Flows from (Used for) Financing Activities	36.6	(347.2)
Cash Flows from Discontinued Operations
Net Increase (Decrease) in Cash and Cash Equivalents	(0.9)	3.2
Cash and Cash Equivalents at Beginning of Period	3.1	3.1
Cash and Cash Equivalents at End of Period	2.2	6.3
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	50.0	60.0
Net Cash Paid (Received) for Income Taxes	76.8	132.3
Noncash Acquisitions Under Capital Leases	1.9	1.7
Construction Expenditures Included in Current Liabilities as of June 30,	50.3	23.1
Public Service Co Of Oklahoma [Member]
Operating Activities
Net Income (Loss)	25.2	44.6
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	66.1	72.7
Deferred Income Taxes	53.7	62.6
Allowance for Equity Funds Used During Construction	(0.4)	(3.8)
Mark-to-Market of Risk Management Contracts	(8.7)	(0.7)
Pension Contributions to Qualified Plan Trust	(5.3)	(5.6)
Property Taxes	(18.9)	(16.0)
Deferred Fuel Over/Under-Recovery, Net	(29.6)	(33.5)
Provision for Refund	(23.3)	11.8
Change in Other Noncurrent Assets	(18.6)	(14.2)
Change in Other Noncurrent Liabilities	(0.7)	(15.2)
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	5.6	(3.8)
Fuel, Materials and Supplies	8.2	(5.6)
Accounts Payable	9.0	27.0
Accrued Taxes, Net	24.0	21.6
Other Current Assets	(1.2)	(1.1)
Other Current Liabilities	(2.7)	4.6
Net Cash Flows from (Used for) Operating Activities	82.4	145.4
Construction Expenditures	(136.2)	(194.0)
Change in Advances to Affiliates, Net	0.0	47.1
Other Investing Activities	1.3	5.1
Net Cash Flows from (Used for) Investing Activities	(134.9)	(141.8)
Financing Activities
Change in Advances from Affiliates, Net	89.4	0.0
Retirement of Long-term Debt	(0.2)	(0.2)
Principal Payments for Capital Lease Obligations	(2.0)	(1.8)
Dividends Paid on Common Stock	(35.0)	0.0
Other Financing Activities	0.2	0.3
Net Cash Flows from (Used for) Financing Activities	52.4	(1.7)
Cash Flows from Discontinued Operations
Net Increase (Decrease) in Cash and Cash Equivalents	(0.1)	1.9
Cash and Cash Equivalents at Beginning of Period	1.5	1.4
Cash and Cash Equivalents at End of Period	1.4	3.3
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	31.7	30.2
Net Cash Paid (Received) for Income Taxes	(42.9)	(42.0)
Noncash Acquisitions Under Capital Leases	0.9	1.6
Construction Expenditures Included in Current Liabilities as of June 30,	29.2	24.3
Southwestern Electric Power Co [Member]
Operating Activities
Net Income (Loss)	42.4	68.8
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	102.9	96.9
Deferred Income Taxes	68.7	96.6
Allowance for Equity Funds Used During Construction	(0.8)	(9.4)
Mark-to-Market of Risk Management Contracts	(11.4)	(3.2)
Pension Contributions to Qualified Plan Trust	(8.9)	(8.3)
Property Taxes	(30.8)	(27.4)
Deferred Fuel Over/Under-Recovery, Net	(3.1)	5.4
Change in Other Noncurrent Assets	(3.3)	11.8
Change in Other Noncurrent Liabilities	(11.1)	(11.0)
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	22.0	2.5
Fuel, Materials and Supplies	3.1	16.8
Accounts Payable	13.2	(1.0)
Accrued Taxes, Net	48.8	(7.5)
Other Current Assets	9.3	(2.7)
Other Current Liabilities	(24.1)	(21.2)
Net Cash Flows from (Used for) Operating Activities	216.9	207.1
Construction Expenditures	(164.7)	(220.7)
Change in Advances to Affiliates, Net	167.8	0.0
Other Investing Activities	3.3	(2.2)
Net Cash Flows from (Used for) Investing Activities	6.4	(222.9)
Financing Activities
Issuance of Long-term Debt	114.7	0.0
Change in Short-term Debt, Net	8.7	0.0
Change in Advances from Affiliates, Net	58.6	96.8
Retirement of Long-term Debt	(351.8)	(1.6)
Principal Payments for Capital Lease Obligations	(5.7)	(9.3)
Dividends Paid on Common Stock	(55.0)	(60.0)
Dividends Paid on Common Stock	(1.7)	(2.3)
Other Financing Activities	0.3	1.0
Net Cash Flows from (Used for) Financing Activities	(231.9)	24.6
Cash Flows from Discontinued Operations
Net Increase (Decrease) in Cash and Cash Equivalents	(8.6)	8.8
Cash and Cash Equivalents at Beginning of Period	10.3	5.2
Cash and Cash Equivalents at End of Period	1.7	14.0
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	66.8	57.5
Net Cash Paid (Received) for Income Taxes	(56.5)	(29.4)
Noncash Acquisitions Under Capital Leases	1.8	5.3
Construction Expenditures Included in Current Liabilities as of June 30,	$ 50.6	$ 68.9