Rate Matters Regulated Operations (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2019	Dec. 31, 2018
Public Utilities, General Disclosures [Line Items]
Gross Investment		$ 21,780.6	$ 21,699.9
Accumulated Depreciation and Amortization		18,182.6	17,986.1
Total Property, Plant and Equipment - Net		55,968.6	55,099.1
Materials and Supplies		586.3	579.6
Regulatory Liability, Noncurrent		8,669.8	8,540.3
Regulatory Assets, Noncurrent		3,297.9	3,310.4
Oklaunion Generating Station [Member] | Generating Units Probable of Abandonment [Member]
Public Utilities, General Disclosures [Line Items]
Gross Investment		106.5
Accumulated Depreciation and Amortization		68.7
Total Property, Plant and Equipment - Net		37.8
Oklaunion Power Station Accelerated Depreciation		10.9
Materials and Supplies		3.1
Regulatory Liability, Noncurrent		$ 5.0
Expected Retirement Date		2020
Remaining Recovery Period, Plant Depreciation		27 years
AEP Texas Inc. [Member]
Public Utilities, General Disclosures [Line Items]
Gross Investment		$ 352.0	352.1
Accumulated Depreciation and Amortization		1,686.6	1,651.2
Total Property, Plant and Equipment - Net		8,220.0	7,991.8
Materials and Supplies		54.1	52.8
Regulatory Liability, Noncurrent		1,344.1	1,344.3
Regulatory Assets, Noncurrent		426.7	430.0
AEP Transmission Co [Member]
Public Utilities, General Disclosures [Line Items]
Accumulated Depreciation and Amortization		306.7	271.9
Total Property, Plant and Equipment - Net		8,260.5	7,996.2
Materials and Supplies		19.6	19.0
Regulatory Liability, Noncurrent		527.9	521.3
Regulatory Assets, Noncurrent		10.5	12.9
Appalachian Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Gross Investment		6,531.5	6,509.6
Accumulated Depreciation and Amortization		4,174.9	4,124.4
Total Property, Plant and Equipment - Net		10,730.7	10,668.3
Materials and Supplies		102.1	100.1
Regulatory Liability, Noncurrent		1,415.7	1,449.7
Regulatory Assets, Noncurrent		469.6	475.8
Indiana Michigan Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Gross Investment		4,895.0	4,887.2
Accumulated Depreciation and Amortization		3,208.4	3,151.6
Total Property, Plant and Equipment - Net		6,680.6	6,611.2
Materials and Supplies		166.1	167.3
Regulatory Liability, Noncurrent		1,743.5	1,574.5
Regulatory Assets, Noncurrent		504.7	512.5
Ohio Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Accumulated Depreciation and Amortization		2,224.1	2,218.6
Total Property, Plant and Equipment - Net		6,395.2	6,274.9
Materials and Supplies		42.9	42.9
Regulatory Liability, Noncurrent		1,234.4	1,221.2
Regulatory Assets, Noncurrent		375.0	387.5
Public Service Co Of Oklahoma [Member]
Public Utilities, General Disclosures [Line Items]
Gross Investment		1,568.6	1,577.0
Accumulated Depreciation and Amortization		1,496.2	1,472.9
Total Property, Plant and Equipment - Net		3,976.9	3,966.7
Materials and Supplies		43.9	44.8
Regulatory Liability, Noncurrent		861.2	864.7
Regulatory Assets, Noncurrent		$ 365.1	369.0
Public Service Co Of Oklahoma [Member] | Oklaunion Generating Station [Member] | Generating Units Probable of Abandonment [Member]
Public Utilities, General Disclosures [Line Items]
Expected Retirement Date		2020
Southwestern Electric Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Gross Investment		$ 4,711.6	4,672.6
Accumulated Depreciation and Amortization		2,760.6	2,808.3
Total Property, Plant and Equipment - Net		6,915.4	6,871.8
Materials and Supplies		69.1	67.5
Regulatory Liability, Noncurrent		922.7	923.0
Regulatory Assets, Noncurrent		226.6	230.8
Regulatory Assets Pending Final Regulatory Approval [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent	[1]	287.8	288.0
Regulatory Assets Pending Final Regulatory Approval [Member] | AEP Texas Inc. [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		152.4	152.6
Regulatory Assets Pending Final Regulatory Approval [Member] | Appalachian Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent	[1]	40.4	44.9
Regulatory Assets Pending Final Regulatory Approval [Member] | Indiana Michigan Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		3.4	3.3
Regulatory Assets Pending Final Regulatory Approval [Member] | Ohio Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		0.1	1.0
Regulatory Assets Pending Final Regulatory Approval [Member] | Public Service Co Of Oklahoma [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		10.9	5.5
Regulatory Assets Pending Final Regulatory Approval [Member] | Southwestern Electric Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		61.0	64.4
Asset Retirement Obligation - Arkansas, Louisiana [Member] | Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Southwestern Electric Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		5.8	5.3
Kentucky Deferred Purchase Power Expenses [Member] | Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		18.4	14.5
Oklaunion Power Station Accelerated Depreciation [Member] | Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Public Service Co Of Oklahoma [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent	[2]	10.9	5.5
Other Regulatory Assets Pending Final Regulatory Approval [Member] | Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		16.4	14.8
Other Regulatory Assets Pending Final Regulatory Approval [Member] | Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Southwestern Electric Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		0.3	0.3
Other Regulatory Assets Pending Final Regulatory Approval [Member] | Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		15.4	20.7
Other Regulatory Assets Pending Final Regulatory Approval [Member] | Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Appalachian Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		0.0	0.6
Other Regulatory Assets Pending Final Regulatory Approval [Member] | Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Indiana Michigan Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		3.4	3.3
Other Regulatory Assets Pending Final Regulatory Approval [Member] | Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Ohio Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		0.1	1.0
Other Regulatory Assets Pending Final Regulatory Approval [Member] | Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Southwestern Electric Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		3.7	3.6
Plant Retirement Costs - Asset Retirement Obligation Costs | Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		35.3	35.3
Plant Retirement Costs - Asset Retirement Obligation Costs | Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Appalachian Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		35.3	35.3
Plant Retirement Costs - Materials and Supplies [Member] | Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Appalachian Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		5.1	9.0
Plant Retirement Costs - Unrecovered Plant [Member] | Regulatory Assets Pending Final Regulatory Approval [Member]
Public Utilities, General Disclosures [Line Items]
Accumulated Depreciation and Amortization		91.0
Plant Retirement Costs - Unrecovered Plant [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Appalachian Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Accumulated Depreciation and Amortization		91.0
Plant Retirement Costs - Unrecovered Plant [Member] | Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		50.3	50.3
Plant Retirement Costs - Unrecovered Plant [Member] | Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Southwestern Electric Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		50.3	50.3
Rate Case Expense - Texas [Member] | Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Southwestern Electric Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		0.9	4.9
Rate Case Expense [Member] | Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | AEP Texas Inc. [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		0.4	0.2
Storm Related Costs [Member] | Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent	[2]	152.0	152.4
Storm Related Costs [Member] | Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | AEP Texas Inc. [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent	[2]	152.0	$ 152.4
Storm Costs Hurricane Harvey [Member] | Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent	[2]	137.0
Storm Costs Hurricane Harvey [Member] | Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | AEP Texas Inc. [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent	[2]	$ 137.0

[1] In 2015, APCo recorded a $91 million reduction to accumulated depreciation related to the remaining net book value of plants retired in 2015, primarily in its Virginia jurisdiction. These plants were normal retirements at the end of their depreciable lives under the group composite method of depreciation. APCo’s recovery of the remaining Virginia net book value for the retired plants will be considered in the Virginia SCC’s 2020 triennial review of APCo’s generation and distribution base rates.

[2] As of March 31, 2019, AEP Texas has deferred $137 million related to Hurricane Harvey. In March 2019, AEP Texas filed a request to securitize total estimated distribution-related system restoration costs with the PUCT. See “Texas Storm Cost Securitization” discussion below for additional information.