Rate Matters Regulated Operations (Details) - USD ($) $ in Millions		6 Months Ended
		Jun. 30, 2019		Dec. 31, 2018
Public Utilities, General Disclosures [Line Items]
Gross Investment		$ 22,098.3		$ 21,699.9
Accumulated Depreciation and Amortization		18,439.1		17,986.1
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		57,202.9		55,099.1
Materials and Supplies		592.7		579.6
Regulatory Liability, Noncurrent		8,556.6		8,540.3
Regulatory Assets, Noncurrent		3,350.1		3,310.4
Oklaunion Generating Station [Member] | Generating Units Probable of Abandonment [Member]
Public Utilities, General Disclosures [Line Items]
Gross Investment		106.6
Accumulated Depreciation and Amortization		74.6
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		32.0
Oklaunion Power Station Accelerated Depreciation	[1]	16.4
Materials and Supplies		3.1
Regulatory Liability, Noncurrent		$ 5.1
Expected Retirement Date		2020
Remaining Recovery Period, Plant Depreciation		27 years
AEP Texas Inc. [Member]
Public Utilities, General Disclosures [Line Items]
Gross Investment		$ 351.8		352.1
Accumulated Depreciation and Amortization		1,712.6		1,651.2
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		8,380.7		7,991.8
Materials and Supplies		54.4		52.8
Regulatory Liability, Noncurrent		1,299.6		1,344.3
Regulatory Assets, Noncurrent		483.5		430.0
AEP Transmission Co [Member]
Public Utilities, General Disclosures [Line Items]
Accumulated Depreciation and Amortization		336.6	[2]	271.9
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		8,570.9	[2]	7,996.2
Materials and Supplies		17.2		19.0
Regulatory Liability, Noncurrent		534.4		521.3
Regulatory Assets, Noncurrent		9.8		12.9
Appalachian Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Gross Investment		6,547.5		6,509.6
Accumulated Depreciation and Amortization		4,230.8		4,124.4
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		10,857.4		10,668.3
Materials and Supplies		101.8		100.1
Regulatory Liability, Noncurrent		1,363.6		1,449.7
Regulatory Assets, Noncurrent		470.1		475.8
Indiana Michigan Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Gross Investment		4,987.2		4,887.2
Accumulated Depreciation and Amortization		3,227.6		3,151.6
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		6,784.1		6,611.2
Materials and Supplies		169.1		167.3
Regulatory Liability, Noncurrent		1,788.0		1,574.5
Regulatory Assets, Noncurrent		492.3		512.5
Ohio Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Accumulated Depreciation and Amortization		2,238.8		2,218.6
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		6,542.3		6,274.9
Materials and Supplies		45.7		42.9
Regulatory Liability, Noncurrent		1,167.7		1,221.2
Regulatory Assets, Noncurrent		370.4		387.5
Public Service Co Of Oklahoma [Member]
Public Utilities, General Disclosures [Line Items]
Gross Investment		1,566.5		1,577.0
Accumulated Depreciation and Amortization		1,527.2		1,472.9
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		4,000.4		3,966.7
Materials and Supplies		46.2		44.8
Regulatory Liability, Noncurrent		860.2		864.7
Regulatory Assets, Noncurrent		375.9		369.0
Public Service Co Of Oklahoma [Member] | Oklaunion Generating Station [Member] | Generating Units Probable of Abandonment [Member]
Public Utilities, General Disclosures [Line Items]
Gross Investment		106.6
Accumulated Depreciation and Amortization		74.6
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		32.0
Oklaunion Power Station Accelerated Depreciation	[1]	16.4
Materials and Supplies		3.1
Regulatory Liability, Noncurrent		$ 5.1
Expected Retirement Date		2020
Remaining Recovery Period, Plant Depreciation		27 years
Southwestern Electric Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Gross Investment		$ 4,670.4		4,672.6
Accumulated Depreciation and Amortization		2,805.2		2,808.3
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		6,955.4		6,871.8
Materials and Supplies		70.7		67.5
Regulatory Liability, Noncurrent		921.6		923.0
Regulatory Assets, Noncurrent		224.0		230.8
Regulatory Assets Pending Final Regulatory Approval [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent	[3]	143.2		288.0
Regulatory Assets Pending Final Regulatory Approval [Member] | AEP Texas Inc. [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		0.7		152.6
Regulatory Assets Pending Final Regulatory Approval [Member] | Appalachian Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent	[3]	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		0.0		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		16.4		6.0
Regulatory Assets Pending Final Regulatory Approval [Member] | Southwestern Electric Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		62.1		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		6.3		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		22.3		14.5
Oklaunion Power Station Accelerated Depreciation [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		5.5
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		16.4		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		5.4		9.3
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		13.5		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		0.0		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] | Public Service Co Of Oklahoma [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		0.0		0.5
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		4.0		3.6
Plant Retirement Costs - Asset Retirement Obligation 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		35.3		35.3
Plant Retirement Costs - Asset Retirement Obligation Costs [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		35.3		35.3
Storm 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	[4]	0.0		152.4
Storm 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	[4]	0.0		152.4
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		1.2		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		$ 0.7		$ 0.2

[1] In October 2018, PSO changed depreciation rates to utilize the 2020 end-of-life and defer depreciation expense to a regulatory asset for the amount in excess of the previously OCC-approved depreciation rates for Oklaunion Power Station. See “2018 Oklahoma Base Rate Case” discussion below for additional information.

[2] Elimination of intercompany interest income/interest expense on affiliated debt arrangement.

[3] 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.

[4] In June 2019, the PUCT approved AEP Texas’ request to securitize its total estimated distribution-related system restoration costs. See “Texas Storm Cost Securitization” discussion below for additional information.