Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Operating Activities
Net Income (Loss)	$ 503.1	$ 630.7
Income from Discontinued Operations	0.0	10.5
Income from Continuing Operations	503.1	620.2
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	497.1	495.4
Deferred Income Taxes	330.2	238.3
Carrying Costs Income	(3.9)	(8.4)
Allowance for Equity Funds Used During Construction	(31.7)	(29.7)
Mark-to-Market of Risk Management Contracts	20.9	(21.0)
Amortization of Nuclear Fuel	40.5	38.3
Property Taxes	(34.4)	(34.8)
Fuel Over/Under-Recovery, Net	10.6	3.4
Deferral of Ohio Capacity Costs, Net	35.1	(6.6)
Change in Other Noncurrent Assets	(68.3)	7.2
Change in Other Noncurrent Liabilities	1.8	(26.2)
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	(10.8)	(2.3)
Fuel, Materials and Supplies	(95.4)	132.1
Accounts Payable	(34.4)	45.8
Accrued Taxes, Net	(169.2)	33.5
Other Current Assets	21.6	(24.4)
Other Current Liabilities	(212.9)	(203.1)
Net Cash Flows from (Used for) Operating Activities	799.9	1,257.7
Investing Activities
Construction Expenditures	(1,203.5)	(1,077.0)
Change in Other Temporary Investments, Net	122.8	93.5
Purchases of Investment Securities	(1,152.0)	(246.2)
Sales of Investment Securities	1,137.7	228.2
Acquisitions of Nuclear Fuel	(45.5)	(51.8)
Other Investing Activities	2.2	32.4
Net Cash Flows from (Used for) Investing Activities	(1,138.3)	(1,020.9)
Financing Activities
Issuance of Common Stock, Net	12.1	30.4
Issuance of Long-term Debt	525.1	773.8
Change in Short-term Debt, Net	421.0	(491.0)
Retirement of Long-term Debt	(322.4)	(238.8)
Principal Payments for Capital Lease Obligations	(24.9)	(27.6)
Dividends Paid on Common Stock	(276.5)	(261.0)
Other Financing Activities	18.0	4.9
Net Cash Flows from (Used for) Financing Activities	352.4	(209.3)
Net Cash Flows from (Used for) Discontinued Operating Activities	0.0	0.2
Net Cash Flows from (Used for) Discontinued Investing Activities	0.0	4.3
Net Cash Flows Used for Discontinued Financing Activities	0.0	(4.1)
Net Increase (Decrease) in Cash and Cash Equivalents	14.0	27.9
Cash and Cash Equivalents at Beginning of Period	176.4	162.5
Cash and Cash Equivalents at End of Period	190.4	190.4
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	199.0	222.6
Net Cash Paid (Received) for Income Taxes	7.3	2.1
Noncash Acquisitions Under Capital Leases	45.4	29.4
Construction Expenditures Included in Current Liabilities as of March 31,	544.3	528.9
Construction Expenditures Included in Noncurrent Liabilities as of March 31,	0.0	43.2
Acquisition of Nuclear Fuel Included in Current Liabilities as of March 31,	29.1	0.0
Appalachian Power Co [Member]
Operating Activities
Net Income (Loss)	126.3	141.8
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	95.5	100.1
Deferred Income Taxes	30.9	49.8
Allowance for Equity Funds Used During Construction	(2.3)	(3.0)
Mark-to-Market of Risk Management Contracts	9.1	9.8
Fuel Over/Under-Recovery, Net	5.1	(26.2)
Change in Other Noncurrent Assets	17.7	3.0
Change in Other Noncurrent Liabilities	(9.0)	(32.0)
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	(26.1)	7.3
Fuel, Materials and Supplies	(28.3)	39.6
Accounts Payable	(2.9)	(2.2)
Accrued Taxes, Net	54.5	31.8
Other Current Assets	(4.1)	(3.0)
Other Current Liabilities	(8.4)	(15.8)
Net Cash Flows from (Used for) Operating Activities	258.0	301.0
Investing Activities
Construction Expenditures	(168.9)	(140.9)
Change in Restricted Cash for Securitized Funding	7.3	7.7
Change in Advances to Affiliates, Net	0.8	(103.6)
Other Investing Activities	4.1	5.3
Net Cash Flows from (Used for) Investing Activities	(156.7)	(231.5)
Financing Activities
Issuance of Long-term Debt	124.8	0.0
Change in Advances from Affiliates, Net	(9.8)	0.0
Retirement of Long-term Debt	(136.5)	(11.0)
Principal Payments for Capital Lease Obligations	(1.5)	(1.3)
Dividends Paid on Common Stock	(75.0)	(56.3)
Other Financing Activities	0.3	0.4
Net Cash Flows from (Used for) Financing Activities	(97.7)	(68.2)
Net Increase (Decrease) in Cash and Cash Equivalents	3.6	1.3
Cash and Cash Equivalents at Beginning of Period	2.8	2.6
Cash and Cash Equivalents at End of Period	6.4	3.9
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	23.1	37.3
Net Cash Paid (Received) for Income Taxes	(17.9)	0.1
Noncash Acquisitions Under Capital Leases	0.7	1.5
Construction Expenditures Included in Current Liabilities as of March 31,	70.4	70.0
Indiana Michigan Power Co [Member]
Operating Activities
Net Income (Loss)	74.7	72.7
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	47.1	51.4
Deferred Income Taxes	44.0	15.6
Deferral of Incremental Nuclear Refueling Outage Expenses, Net	8.4	9.3
Allowance for Equity Funds Used During Construction	(2.3)	(4.0)
Mark-to-Market of Risk Management Contracts	2.4	12.4
Amortization of Nuclear Fuel	40.5	38.3
Fuel Over/Under-Recovery, Net	3.8	(3.0)
Change in Other Noncurrent Assets	(4.8)	5.9
Change in Other Noncurrent Liabilities	9.1	(7.5)
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	(2.0)	31.9
Fuel, Materials and Supplies	(16.0)	8.8
Accounts Payable	(9.9)	(0.2)
Accrued Taxes, Net	2.5	28.5
Other Current Assets	6.1	7.6
Other Current Liabilities	(32.5)	(30.7)
Net Cash Flows from (Used for) Operating Activities	154.3	218.4
Investing Activities
Construction Expenditures	(136.4)	(111.8)
Change in Advances to Affiliates, Net	(0.6)	0.0
Purchases of Investment Securities	(1,151.6)	(245.8)
Sales of Investment Securities	1,137.7	228.2
Acquisitions of Nuclear Fuel	(45.5)	(51.8)
Other Investing Activities	3.3	5.5
Net Cash Flows from (Used for) Investing Activities	(193.1)	(175.7)
Financing Activities
Issuance of Long-term Debt	394.8	0.0
Change in Advances from Affiliates, Net	(284.8)	25.7
Retirement of Long-term Debt	(28.8)	(25.9)
Principal Payments for Capital Lease Obligations	(9.6)	(12.2)
Dividends Paid on Common Stock	(31.3)	(30.0)
Other Financing Activities	0.7	0.5
Net Cash Flows from (Used for) Financing Activities	41.0	(41.9)
Net Increase (Decrease) in Cash and Cash Equivalents	2.2	0.8
Cash and Cash Equivalents at Beginning of Period	1.1	1.0
Cash and Cash Equivalents at End of Period	3.3	1.8
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	35.2	35.0
Net Cash Paid (Received) for Income Taxes	(4.9)	2.0
Noncash Acquisitions Under Capital Leases	14.9	0.8
Construction Expenditures Included in Current Liabilities as of March 31,	68.4	66.3
Acquisition of Nuclear Fuel Included in Current Liabilities as of March 31,	29.1	0.0
Expected Reimbursement For Spent Nuclear Fuel Dry Cask Storage	0.0	0.1
Ohio Power Co [Member]
Operating Activities
Net Income (Loss)	70.2	65.4
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	61.3	59.2
Amortization Of Generation Deferrals	55.1	31.4
Deferred Income Taxes	7.3	1.7
Carrying Costs Income	(1.9)	(6.5)
Allowance for Equity Funds Used During Construction	(1.7)	(2.4)
Mark-to-Market of Risk Management Contracts	26.9	1.5
Property Taxes	56.0	49.8
Deferral of Ohio Capacity Costs, Net	0.0	(18.2)
Change in Other Noncurrent Assets	(16.2)	32.6
Change in Other Noncurrent Liabilities	6.5	25.4
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	(4.7)	4.7
Fuel, Materials and Supplies	(3.0)	(7.3)
Accounts Payable	(30.4)	(25.2)
Customer Deposits	24.0	0.9
Accrued Taxes, Net	(148.4)	(59.5)
Other Current Assets	(0.4)	(1.2)
Other Current Liabilities	(20.7)	(7.2)
Net Cash Flows from (Used for) Operating Activities	79.9	145.1
Investing Activities
Construction Expenditures	(99.2)	(119.7)
Change in Restricted Cash for Securitized Funding	11.5	11.6
Change in Advances to Affiliates, Net	109.2	21.2
Other Investing Activities	3.1	2.8
Net Cash Flows from (Used for) Investing Activities	24.6	(84.1)
Financing Activities
Retirement of Long-term Debt	(22.8)	(22.2)
Principal Payments for Capital Lease Obligations	(1.0)	(0.9)
Dividends Paid on Common Stock	(75.0)	(37.5)
Other Financing Activities	0.5	1.1
Net Cash Flows from (Used for) Financing Activities	(98.3)	(59.5)
Net Increase (Decrease) in Cash and Cash Equivalents	6.2	1.5
Cash and Cash Equivalents at Beginning of Period	3.1	2.9
Cash and Cash Equivalents at End of Period	9.3	4.4
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	17.8	18.8
Net Cash Paid (Received) for Income Taxes	72.5	0.0
Noncash Acquisitions Under Capital Leases	0.8	1.6
Construction Expenditures Included in Current Liabilities as of March 31,	23.1	42.9
Public Service Co Of Oklahoma [Member]
Operating Activities
Net Income (Loss)	15.7	13.7
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	35.3	29.5
Deferred Income Taxes	30.5	8.9
Allowance for Equity Funds Used During Construction	(2.3)	(1.3)
Mark-to-Market of Risk Management Contracts	0.0	(0.2)
Property Taxes	(24.1)	(24.2)
Fuel Over/Under-Recovery, Net	(8.3)	25.0
Change in Regulatory Assets	(3.9)	0.1
Change in Regulatory Liabilities	(1.1)	8.1
Change in Other Noncurrent Assets	(6.3)	(5.1)
Change in Other Noncurrent Liabilities	(0.4)	8.5
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	5.0	4.5
Fuel, Materials and Supplies	(3.5)	(2.0)
Accounts Payable	(17.6)	(6.8)
Accrued Taxes, Net	17.6	14.8
Other Current Assets	(0.2)	(9.0)
Other Current Liabilities	(4.0)	(7.3)
Net Cash Flows from (Used for) Operating Activities	32.4	57.2
Investing Activities
Construction Expenditures	(104.1)	(90.2)
Change in Advances to Affiliates, Net	72.2	(62.3)
Other Investing Activities	2.1	1.2
Net Cash Flows from (Used for) Investing Activities	(29.8)	(151.3)
Financing Activities
Issuance of Long-term Debt	0.0	248.8
Change in Advances from Affiliates, Net	0.0	(154.2)
Retirement of Long-term Debt	(0.1)	(0.1)
Principal Payments for Capital Lease Obligations	(1.0)	(1.0)
Other Financing Activities	0.3	0.7
Net Cash Flows from (Used for) Financing Activities	(0.8)	94.2
Net Increase (Decrease) in Cash and Cash Equivalents	1.8	0.1
Cash and Cash Equivalents at Beginning of Period	1.4	1.3
Cash and Cash Equivalents at End of Period	3.2	1.4
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	15.1	11.0
Net Cash Paid (Received) for Income Taxes	(23.2)	0.0
Noncash Acquisitions Under Capital Leases	1.4	0.9
Construction Expenditures Included in Current Liabilities as of March 31,	35.7	30.8
Southwestern Electric Power Co [Member]
Operating Activities
Net Income (Loss)	24.5	46.7
Adjustments to Reconcile Net Income to Net Cash Flows from (Used for) Operating Activities:
Depreciation and Amortization	47.5	47.0
Deferred Income Taxes	44.6	18.8
Allowance for Equity Funds Used During Construction	(7.4)	(5.2)
Mark-to-Market of Risk Management Contracts	0.1	3.1
Property Taxes	(41.4)	(39.4)
Fuel Over/Under-Recovery, Net	3.7	2.8
Change in Other Noncurrent Assets	5.3	(0.9)
Change in Other Noncurrent Liabilities	(1.9)	(2.9)
Changes in Certain Components of Working Capital:
Accounts Receivable, Net	2.6	26.0
Fuel, Materials and Supplies	13.7	(0.5)
Accounts Payable	(19.9)	(28.3)
Accrued Taxes, Net	(13.2)	43.1
Accrued Interest	(20.8)	(25.5)
Other Current Assets	(1.7)	(11.4)
Other Current Liabilities	(28.2)	(44.1)
Net Cash Flows from (Used for) Operating Activities	7.5	29.3
Investing Activities
Construction Expenditures	(116.6)	(138.1)
Change in Advances to Affiliates, Net	0.0	(252.3)
Other Investing Activities	(7.0)	(1.4)
Net Cash Flows from (Used for) Investing Activities	(123.6)	(391.8)
Financing Activities
Issuance of Long-term Debt	0.0	446.0
Change in Advances from Affiliates, Net	159.5	0.0
Retirement of Long-term Debt	(1.6)	(55.1)
Principal Payments for Capital Lease Obligations	(4.5)	(4.5)
Dividends Paid on Common Stock	(30.0)	(30.0)
Dividends Paid on Common Stock	(1.2)	(1.0)
Other Financing Activities	1.0	0.7
Net Cash Flows from (Used for) Financing Activities	123.2	356.1
Net Increase (Decrease) in Cash and Cash Equivalents	7.1	(6.4)
Cash and Cash Equivalents at Beginning of Period	5.2	14.4
Cash and Cash Equivalents at End of Period	12.3	8.0
Supplementary Information
Cash Paid for Interest, Net of Capitalized Amounts	47.7	53.4
Net Cash Paid (Received) for Income Taxes	14.0	(0.9)
Noncash Acquisitions Under Capital Leases	4.9	0.9
Construction Expenditures Included in Current Liabilities as of March 31,	$ 83.7	$ 80.2