Significant Accounting Matters (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Amounts Attributable to AEP Common Shareholders
Income (Loss) from Continuing Operations, Including Portion Attributable to Noncontrolling Interest	$ 556.7	$ (764.2)	$ 1,527.1	$ 245.3
Net Income Attributable to Noncontrolling Interests	12.0	1.6	15.2	5.3
Income (Loss) from Continuing Operations Attributable to Parent	$ 544.7	$ (765.8)	$ 1,511.9	$ 240.0
Weighted Average Number of Basic AEP Common Shares Outstanding	491,840,722	491,697,809	491,781,643	491,422,921
Basic Earnings Per Share Attributable to AEP Common Shareholders from Continuing Operations	$ 1.11	$ (1.56)	$ 3.07	$ 0.49
Weighted Average Dilutive Effect of:
Weighted Average Number of Diluted AEP Common Shares Outstanding	492,986,307	491,813,858	492,428,586	491,596,861
Diluted Earnings Per Share Attributable to AEP Common Shareholders from Continuing Operations	$ 1.10	$ (1.56)	$ 3.07	$ 0.49
Organization and Summary of Significant Accounting Policies (Textuals) [Abstract]
Antidilutive Shares Outstanding			0	0
Income (Loss) from Equity Method Investments Adjustment			$ 6.0
Cash Paid Received for [Abstract]
Cash Paid for Interest, Net of Capitalized Amounts			613.8	$ 637.0
Net Cash Paid (Received) for Income Taxes			(6.8)	32.2
Noncash Investing and Financing Activities:
Noncash Acquisitions Under Capital Leases			44.5	65.8
Construction Expenditures Included in Current Liabilities as of September 30,			791.6	604.8
Construction Expenditures Included in Noncurrent Liabilities as of September 30,			71.8	0.0
Acquisition Of Nuclear Fuel Included In Current Liabilities as of September 30,			0.6	0.3
Expected Reimbursement for Spent Nuclear Fuel Dry Cask Storage			2.8	0.0
AEP Transmission Co [Member]
Cash Paid Received for [Abstract]
Cash Paid for Interest, Net of Capitalized Amounts			28.6	20.0
Net Cash Paid (Received) for Income Taxes			(93.4)	(209.8)
Noncash Investing and Financing Activities:
Construction Expenditures Included in Current Liabilities as of September 30,			239.0	204.8
Appalachian Power Co [Member]
Cash Paid Received for [Abstract]
Cash Paid for Interest, Net of Capitalized Amounts			107.1	113.2
Net Cash Paid (Received) for Income Taxes			24.4	55.8
Noncash Investing and Financing Activities:
Noncash Acquisitions Under Capital Leases			2.9	2.1
Construction Expenditures Included in Current Liabilities as of September 30,			107.2	66.8
Indiana Michigan Power Co [Member]
Cash Paid Received for [Abstract]
Cash Paid for Interest, Net of Capitalized Amounts			92.0	85.6
Net Cash Paid (Received) for Income Taxes			(69.6)	(36.0)
Noncash Investing and Financing Activities:
Noncash Acquisitions Under Capital Leases			5.9	16.8
Construction Expenditures Included in Current Liabilities as of September 30,			74.5	83.4
Acquisition Of Nuclear Fuel Included In Current Liabilities as of September 30,			0.6	0.3
Expected Reimbursement for Spent Nuclear Fuel Dry Cask Storage			2.8	0.1
Ohio Power Co [Member]
Cash Paid Received for [Abstract]
Cash Paid for Interest, Net of Capitalized Amounts			68.1	78.2
Net Cash Paid (Received) for Income Taxes			69.6	178.0
Noncash Investing and Financing Activities:
Noncash Acquisitions Under Capital Leases			3.6	2.4
Construction Expenditures Included in Current Liabilities as of September 30,			56.8	30.0
Public Service Co Of Oklahoma [Member]
Cash Paid Received for [Abstract]
Cash Paid for Interest, Net of Capitalized Amounts			40.9	45.0
Net Cash Paid (Received) for Income Taxes			(46.6)	(50.3)
Noncash Investing and Financing Activities:
Noncash Acquisitions Under Capital Leases			1.0	2.2
Construction Expenditures Included in Current Liabilities as of September 30,			15.1	20.2
Southwestern Electric Power Co [Member]
Amounts Attributable to AEP Common Shareholders
Net Income Attributable to Noncontrolling Interests	$ 11.0	$ 1.1	12.6	3.3
Organization and Summary of Significant Accounting Policies (Textuals) [Abstract]
Income (Loss) from Equity Method Investments Adjustment			6.3
Cash Paid Received for [Abstract]
Cash Paid for Interest, Net of Capitalized Amounts			109.4	107.6
Net Cash Paid (Received) for Income Taxes			(70.5)	(66.6)
Noncash Investing and Financing Activities:
Noncash Acquisitions Under Capital Leases			2.8	5.5
Construction Expenditures Included in Current Liabilities as of September 30,			$ 40.7	$ 54.3
Restricted Stock Units and Performance Share Units [Member]
Weighted Average Dilutive Effect of:
Weighted Average Dilutive Effect of Shares	1,200,000	100,000	600,000	200,000
Dilutive Securities, Effect on Basic Earnings Per Share	$ (0.01)	$ (0.00)	$ (0.00)	$ (0.00)