Significant Accounting Matters (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Amounts Attributable to AEP Common Shareholders
Income (Loss) from Continuing Operations, Including Portion Attributable to Noncontrolling Interest	$ 376.2	$ 506.4	$ 970.4	$ 1,009.5
Net Income Attributable to Noncontrolling Interests	1.2	1.8	3.2	3.7
Income (Loss) from Continuing Operations Attributable to Parent	$ 375.0	$ 504.6	$ 967.2	$ 1,005.8
Weighted Average Number of Basic AEP Common Shares Outstanding	491,790,752	491,459,541	491,751,614	491,283,967
Basic Earnings Per Share Attributable to AEP Common Shareholders from Continuing Operations	$ 0.76	$ 1.03	$ 1.97	$ 2.05
Weighted Average Dilutive Effect of:
Weighted Average Number of Diluted AEP Common Shares Outstanding	492,642,100	491,641,400	492,337,255	491,486,853
Diluted Earnings Per Share Attributable to AEP Common Shareholders from Continuing Operations	$ 0.76	$ 1.03	$ 1.96	$ 2.05
Organization and Summary of Significant Accounting Policies (Textuals) [Abstract]
Antidilutive Shares Outstanding			0	0
Income (Loss) from Equity Method Investments Adjustment			$ 6.3
Cash Paid Received for [Abstract]
Cash Paid for Interest, Net of Capitalized Amounts			442.3	$ 425.4
Net Cash Paid (Received) for Income Taxes			(21.2)	26.2
Noncash Investing and Financing Activities:
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]
Cash Paid Received for [Abstract]
Cash Paid for Interest, Net of Capitalized Amounts			31.4	20.3
Net Cash Paid (Received) for Income Taxes			(67.0)	(178.0)
Noncash Investing and Financing Activities:
Construction Expenditures Included in Current Liabilities as of June 30,			190.3	155.0
Appalachian Power Co [Member]
Cash Paid Received for [Abstract]
Cash Paid for Interest, Net of Capitalized Amounts			92.4	90.9
Net Cash Paid (Received) for Income Taxes			32.0	28.3
Noncash Investing and Financing Activities:
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]
Cash Paid Received for [Abstract]
Cash Paid for Interest, Net of Capitalized Amounts			49.2	40.3
Net Cash Paid (Received) for Income Taxes			(56.9)	(23.6)
Noncash Investing and Financing Activities:
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]
Cash Paid Received for [Abstract]
Cash Paid for Interest, Net of Capitalized Amounts			50.0	60.0
Net Cash Paid (Received) for Income Taxes			76.8	132.3
Noncash Investing and Financing Activities:
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]
Cash Paid Received for [Abstract]
Cash Paid for Interest, Net of Capitalized Amounts			31.7	30.2
Net Cash Paid (Received) for Income Taxes			(42.9)	(42.0)
Noncash Investing and Financing Activities:
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]
Amounts Attributable to AEP Common Shareholders
Net Income Attributable to Noncontrolling Interests	$ 0.6	$ 1.1	1.6	2.2
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			66.8	57.5
Net Cash Paid (Received) for Income Taxes			(56.5)	(29.4)
Noncash Investing and Financing Activities:
Noncash Acquisitions Under Capital Leases			1.8	5.3
Construction Expenditures Included in Current Liabilities as of June 30,			$ 50.6	$ 68.9
Restricted Stock Units and Performance Share Units [Member]
Weighted Average Dilutive Effect of:
Weighted Average Dilutive Effect of Shares	800,000	100,000	500,000	200,000
Dilutive Securities, Effect on Basic Earnings Per Share	$ 0.0	$ 0.0	$ (0.01)	$ 0.0