Rate Matters Regulated Operations (Details) - USD ($) $ in Millions		3 Months Ended				9 Months Ended
		Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Public Utilities, General Disclosures [Line Items]
Property, Plant and Equipment		$ 24,135.9				$ 24,135.9		$ 23,133.9
Accumulated Depreciation		21,877.0				21,877.0		20,411.4
Net Investment		66,691.2				66,691.2		63,901.6
Materials and Supplies		688.4				688.4		680.6
Asset Retirement Obligation, Revision of Estimate	[1],[2],[3],[4]					75.1
Regulatory Assets, Noncurrent		5,031.5				5,031.5		3,527.0
Customers		701.2				701.2		613.6
Proceeds from Issuance of Debt	[5]					5,115.8
Fuel Over Under Recovery Net						1,356.8	$ (27.4)
Senior Unsecured Notes [Member]
Public Utilities, General Disclosures [Line Items]
Proceeds from Issuance of Debt	[5]					175.0
February 2021 Storm Event
Public Utilities, General Disclosures [Line Items]
Capitalized Storm Costs						66.6
Incremental Other Operation and Maintenance Expenses						7.2
Deferred Storm Costs as a Regulated Asset						141.6
Total Estimated February 2021 Storm Restoration Expenditures						215.4
February 2021 Severe Storm Fuel Costs
Public Utilities, General Disclosures [Line Items]
Customers		55.8				55.8
Total Estimated 2021 February Winter Storm Fuel Costs		1,162.1				1,162.1
February 2021 Severe Storm Fuel Costs | 364 Day Term Loan
Public Utilities, General Disclosures [Line Items]
Proceeds from Issuance of Debt						500.0
AEP Texas Inc. [Member]
Public Utilities, General Disclosures [Line Items]
Accumulated Depreciation		1,621.1				1,621.1		1,529.3
Net Investment		10,313.4				10,313.4		9,813.6
Materials and Supplies		72.5				72.5		70.0
Regulatory Assets, Noncurrent		290.4				290.4		266.8
Customers		142.1				142.1		112.8
AEP Texas Inc. [Member] | Senior Unsecured Notes [Member]
Public Utilities, General Disclosures [Line Items]
Proceeds from Issuance of Debt	[5]					450.0
AEP Transmission Co [Member]
Public Utilities, General Disclosures [Line Items]
Accumulated Depreciation		730.4				730.4		572.8
Net Investment		11,628.9				11,628.9		10,772.8
Materials and Supplies		9.0				9.0		8.5
Regulatory Assets, Noncurrent		10.1				10.1		15.1
Customers		31.0				31.0		22.9
Capital Contribution from Member			$ 60.0	$ 124.0	$ 185.0
AEP Transmission Co [Member] | Additional Paid-in Capital [Member]
Public Utilities, General Disclosures [Line Items]
Capital Contribution from Member			60.0	124.0	$ 185.0
AEP Transmission Co [Member] | Senior Unsecured Notes [Member]
Public Utilities, General Disclosures [Line Items]
Proceeds from Issuance of Debt	[5]					450.0
Appalachian Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Property, Plant and Equipment		6,670.8				6,670.8		6,633.7
Accumulated Depreciation		4,973.1				4,973.1		4,716.2
Net Investment		11,621.8				11,621.8		11,394.1
Materials and Supplies		100.3				100.3		99.6
Asset Retirement Obligation, Revision of Estimate	[2],[3]					84.7
Regulatory Assets, Noncurrent		818.6				818.6		686.3
Customers		119.3				119.3		142.8
Fuel Over Under Recovery Net						43.9	(38.8)
Appalachian Power Co [Member] | Senior Unsecured Notes [Member]
Public Utilities, General Disclosures [Line Items]
Proceeds from Issuance of Debt						500.0
Appalachian Power Co [Member] | February 2021 Storm Event | Virginia
Public Utilities, General Disclosures [Line Items]
Capitalized Storm Costs						8.1
Incremental Other Operation and Maintenance Expenses						2.2
Deferred Storm Costs as a Regulated Asset						6.6
Total Estimated February 2021 Storm Restoration Expenditures						16.9
Appalachian Power Co [Member] | February 2021 Storm Event | West Virginia
Public Utilities, General Disclosures [Line Items]
Capitalized Storm Costs						23.5
Incremental Other Operation and Maintenance Expenses						0.0
Deferred Storm Costs as a Regulated Asset						47.0
Total Estimated February 2021 Storm Restoration Expenditures						70.5
Indiana Michigan Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Property, Plant and Equipment		5,329.6				5,329.6		5,264.7
Accumulated Depreciation		3,811.9				3,811.9		3,552.5
Net Investment		7,063.8				7,063.8		7,052.3
Materials and Supplies		172.2				172.2		175.8
Regulatory Assets, Noncurrent		436.1				436.1		404.8
Customers		39.8				39.8		44.0
Fuel Over Under Recovery Net						18.0	(23.4)
Indiana Michigan Power Co [Member] | Senior Unsecured Notes [Member]
Public Utilities, General Disclosures [Line Items]
Proceeds from Issuance of Debt	[5]					450.0
Ohio Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Accumulated Depreciation		2,438.7				2,438.7		2,350.0
Net Investment		7,798.4				7,798.4		7,452.1
Materials and Supplies		70.9				70.9		66.9
Regulatory Assets, Noncurrent		343.8				343.8		385.8
Customers		31.0				31.0		50.0
Ohio Power Co [Member] | Senior Unsecured Notes [Member]
Public Utilities, General Disclosures [Line Items]
Proceeds from Issuance of Debt	[5]					450.0
Public Service Co Of Oklahoma [Member]
Public Utilities, General Disclosures [Line Items]
Property, Plant and Equipment		1,795.2				1,795.2		1,480.7
Accumulated Depreciation		1,682.6				1,682.6		1,605.6
Net Investment		4,723.7				4,723.7		4,320.0
Materials and Supplies		54.4				54.4		54.0
Regulatory Assets, Noncurrent		1,052.3				1,052.3		375.0
Customers		29.7				29.7		30.8
Capital Contribution from Member			200.0	425.0
Fuel Over Under Recovery Net						776.4	46.6
Public Service Co Of Oklahoma [Member] | Additional Paid-in Capital [Member]
Public Utilities, General Disclosures [Line Items]
Capital Contribution from Member			200.0	425.0
Public Service Co Of Oklahoma [Member] | Senior Unsecured Notes [Member]
Public Utilities, General Disclosures [Line Items]
Proceeds from Issuance of Debt	[5]					400.0
Public Service Co Of Oklahoma [Member] | February 2021 Severe Storm Fuel Costs
Public Utilities, General Disclosures [Line Items]
Recommended Disallowance from Staff or Intervenors						40.0
Customers		0.0				0.0
Total Estimated 2021 February Winter Storm Fuel Costs		673.2				$ 673.2
Interim WACC						0.75%
Public Service Co Of Oklahoma [Member] | February 2021 Severe Storm Fuel Costs | Minimum [Member]
Public Utilities, General Disclosures [Line Items]
Intervenor Recommended WACC						0.75%
Public Service Co Of Oklahoma [Member] | February 2021 Severe Storm Fuel Costs | Maximum [Member]
Public Utilities, General Disclosures [Line Items]
Intervenor Recommended WACC						2.32%
Public Service Co Of Oklahoma [Member] | Northeastern Plant, Unit 3 | Generating Units Probable of Abandonment [Member]
Public Utilities, General Disclosures [Line Items]
Net Investment		175.1				$ 175.1
Accelerated Depreciation Regulatory Asset		123.6				123.6
Cost of Removal Regulatory Liability	[6]	20.0				$ 20.0
Expected Retirement Date	[7]					2026
Depreciation	[8]					$ 14.9
Public Service Co Of Oklahoma [Member] | February 2021 Severe Storm Fuel Costs
Public Utilities, General Disclosures [Line Items]
Capital Contribution from Member			125.0	425.0
Public Service Co Of Oklahoma [Member] | February 2021 Severe Storm Fuel Costs | Other Long Term Debt [Member]
Public Utilities, General Disclosures [Line Items]
Proceeds from Issuance of Debt						100.0
Southwestern Electric Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Property, Plant and Equipment		5,065.5				5,065.5		4,681.4
Accumulated Depreciation		3,478.5				3,478.5		3,158.5
Net Investment		7,363.9				7,363.9		7,088.2
Materials and Supplies		86.8				86.8		95.8
Regulatory Assets, Noncurrent		1,068.0				1,068.0		403.1
Customers		76.2				76.2		27.1
Capital Contribution from Member		105.0	75.0	100.0
Fuel Over Under Recovery Net						506.8	$ (16.3)
Net Under-Recovered Fuel Costs		39.0				39.0
Southwestern Electric Power Co [Member] | Additional Paid-in Capital [Member]
Public Utilities, General Disclosures [Line Items]
Capital Contribution from Member		105.0	$ 75.0	100.0
Southwestern Electric Power Co [Member] | Senior Unsecured Notes [Member]
Public Utilities, General Disclosures [Line Items]
Proceeds from Issuance of Debt	[5]					500.0
Southwestern Electric Power Co [Member] | 2020 Texas Fuel Reconciliation
Public Utilities, General Disclosures [Line Items]
Amount of Fuel Costs Under Review		1,700.0				1,700.0
Southwestern Electric Power Co [Member] | 2020 Texas Fuel Reconciliation | TEXAS
Public Utilities, General Disclosures [Line Items]
Amount of Fuel Costs Under Review		616.0				616.0
Recommended Disallowance from Staff or Intervenors						125.0
Reduction in Recoverable Fuel Costs						10.0
Southwestern Electric Power Co [Member] | February 2021 Storm Event
Public Utilities, General Disclosures [Line Items]
Capitalized Storm Costs						6.0
Incremental Other Operation and Maintenance Expenses						0.0
Deferred Storm Costs as a Regulated Asset						45.4
Total Estimated February 2021 Storm Restoration Expenditures						51.4
Southwestern Electric Power Co [Member] | February 2021 Severe Storm Fuel Costs
Public Utilities, General Disclosures [Line Items]
Customers		55.8				55.8
Total Estimated 2021 February Winter Storm Fuel Costs		488.9				488.9
Amount Billed to Wholesale Customers						$ 104.0
Southwestern Electric Power Co [Member] | February 2021 Severe Storm Fuel Costs | Arkansas
Public Utilities, General Disclosures [Line Items]
Requested Weighted Average Cost of Capital						6.05%
Intervenor Recommended WACC						1.65%
Interim WACC						0.80%
Southwestern Electric Power Co [Member] | February 2021 Severe Storm Fuel Costs | Louisiana Jurisdiction [Member]
Public Utilities, General Disclosures [Line Items]
Interim WACC						3.25%
Southwestern Electric Power Co [Member] | February 2021 Severe Storm Fuel Costs | Texas
Public Utilities, General Disclosures [Line Items]
Requested Weighted Average Cost of Capital						7.18%
Southwestern Electric Power Co [Member] | February 2021 Severe Storm Fuel Costs | Texas | Minimum [Member]
Public Utilities, General Disclosures [Line Items]
Intervenor Recommended WACC						0.082%
Southwestern Electric Power Co [Member] | February 2021 Severe Storm Fuel Costs | Texas | Maximum [Member]
Public Utilities, General Disclosures [Line Items]
Intervenor Recommended WACC						1.625%
Southwestern Electric Power Co [Member] | Dolet Hills Power Station [Member] | Generating Units Probable of Abandonment [Member]
Public Utilities, General Disclosures [Line Items]
Net Investment		13.0				$ 13.0
Accelerated Depreciation Regulatory Asset		126.8				126.8
Cost of Removal Regulatory Liability		24.4				$ 24.4
Expected Retirement Date	[9]					2021
Depreciation	[8]					$ 7.8
Southwestern Electric Power Co [Member] | Dolet Hills Power Station and Related Fuel Operations
Public Utilities, General Disclosures [Line Items]
Percent of Fuel Supply Provided by DHLC						100.00%
Share of Net Investment in Dolet Hills Power Station		146.0				$ 146.0
Dolet Hills Lignite Company Unbilled Fixed Costs		44.0				44.0
Recovery of 2021 Dolet Hills Fuel Costs						20.0
Approved Deferral of Dolet Hills Fuel Costs						30.0
Southwestern Electric Power Co [Member] | Pirkey Power Plant and Related Fuel Operations
Public Utilities, General Disclosures [Line Items]
Share of Net Investment in Pirkey Power Plant		203.0				203.0
Pirkey Power Plant and Sabine Unbilled Fixed Costs		108.0				108.0
Southwestern Electric Power Co [Member] | Pirkey Generating Station (Unit No. 1) | Generating Units Probable of Abandonment [Member]
Public Utilities, General Disclosures [Line Items]
Net Investment		135.4				135.4
Accelerated Depreciation Regulatory Asset		68.0				68.0
Cost of Removal Regulatory Liability		39.2				$ 39.2
Expected Retirement Date	[10]					2023
Depreciation	[8]					$ 13.5
Southwestern Electric Power Co [Member] | Welsh Plant Unit 1 and 3 | Generating Units Probable of Abandonment [Member]
Public Utilities, General Disclosures [Line Items]
Net Investment		493.7				493.7
Accelerated Depreciation Regulatory Asset		35.6				35.6
Cost of Removal Regulatory Liability	[11]	58.2				$ 58.2
Expected Retirement Date	[12]					2028
Depreciation	[8]					$ 33.1
Southwestern Electric Power Co [Member] | February 2021 Severe Storm Fuel Costs
Public Utilities, General Disclosures [Line Items]
Capital Contribution from Member				$ 100.0
Southwestern Electric Power Co [Member] | February 2021 Severe Storm Fuel Costs | Senior Unsecured Notes [Member]
Public Utilities, General Disclosures [Line Items]
Proceeds from Issuance of Debt						500.0
Kentucky Power Co [Member] | Other Long Term Debt [Member]
Public Utilities, General Disclosures [Line Items]
Proceeds from Issuance of Debt	[5]					150.0
Kentucky Power Co [Member] | February 2021 Storm Event
Public Utilities, General Disclosures [Line Items]
Capitalized Storm Costs						29.0
Incremental Other Operation and Maintenance Expenses						5.0
Deferred Storm Costs as a Regulated Asset						42.6
Total Estimated February 2021 Storm Restoration Expenditures						76.6
Regulatory Assets Pending Final Regulatory Approval [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		1,904.9				1,904.9		442.2
Regulatory Assets Pending Final Regulatory Approval [Member] | AEP Texas Inc. [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		57.8				57.8		32.9
Regulatory Assets Pending Final Regulatory Approval [Member] | Appalachian Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		93.9				93.9		43.8
Regulatory Assets Pending Final Regulatory Approval [Member] | Indiana Michigan Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		3.4				3.4		4.3
Regulatory Assets Pending Final Regulatory Approval [Member] | Ohio Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		7.5				7.5		8.4
Regulatory Assets Pending Final Regulatory Approval [Member] | Public Service Co Of Oklahoma [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		736.4				736.4		50.5
Regulatory Assets Pending Final Regulatory Approval [Member] | Southwestern Electric Power Co [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		906.0				906.0		247.3
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | February 2021 Severe Storm Fuel Costs
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent	[13]	1,106.3				1,106.3
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Oklaunion Power Station Accelerated Depreciation [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		33.0				33.0		34.4
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Kentucky Deferred Purchase Power Expenses [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		45.9				45.9		41.3
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Plant Retirement Costs - Unrecovered Plant [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		35.2				35.2		35.2
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Dolet Hills Power Station Accelerated Depreciation [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		126.8				126.8		71.2
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Other Regulatory Assets Not Yet Being Recovered [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		25.5				25.5		22.8
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | February 2021 Severe Storm Fuel Costs
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent	[14]	1,106.3				1,106.3		0.0
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Pirkey Power Plant Accelerated Depreciation
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		68.0				68.0		12.2
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Welsh Unit 1 and 3 Accelerated Depreciation
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		35.6				35.6		3.6
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Dolet Hills Power Station Fuel Costs
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		20.3				20.3		0.0
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | AEP Texas Inc. [Member] | Adavanced Metering System
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		16.6				16.6		16.3
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Appalachian Power Co [Member] | COVID-19 - Virginia
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		6.6				6.6		3.7
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Indiana Michigan Power Co [Member] | Other Regulatory Assets Not Yet Being Recovered [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		0.0				0.0		0.5
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Public Service Co Of Oklahoma [Member] | February 2021 Severe Storm Fuel Costs
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent	[13]	673.2				673.2
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Public Service Co Of Oklahoma [Member] | Oklaunion Power Station Accelerated Depreciation [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		33.0				33.0		34.4
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Public Service Co Of Oklahoma [Member] | February 2021 Severe Storm Fuel Costs
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent	[15]	673.2				673.2		0.0
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Southwestern Electric Power Co [Member] | February 2021 Severe Storm Fuel Costs
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent	[13],[16]	433.1				433.1
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Southwestern Electric Power Co [Member] | February 2021 Severe Storm Fuel Costs | Arkansas
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		107.0				107.0
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Southwestern Electric Power Co [Member] | February 2021 Severe Storm Fuel Costs | Louisiana Jurisdiction [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		151.0				151.0
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Southwestern Electric Power Co [Member] | February 2021 Severe Storm Fuel Costs | Texas
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		175.0				175.0
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Southwestern Electric Power Co [Member] | Dolet Hills Power Station Accelerated Depreciation [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		126.8				126.8		71.2
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Southwestern Electric Power Co [Member] | Plant Retirement Costs - Unrecovered Plant, Louisiana [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		35.2				35.2		35.2
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Southwestern Electric Power Co [Member] | Other Regulatory Assets Not Yet Being Recovered [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		2.3				2.3		2.2
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Southwestern Electric Power Co [Member] | February 2021 Severe Storm Fuel Costs
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent	[17]	433.1				433.1		0.0
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Southwestern Electric Power Co [Member] | Pirkey Power Plant Accelerated Depreciation
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		68.0				68.0		12.2
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Southwestern Electric Power Co [Member] | Welsh Unit 1 and 3 Accelerated Depreciation
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		35.6				35.6		3.6
Regulatory Assets Currently Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Southwestern Electric Power Co [Member] | Dolet Hills Power Station Fuel Costs
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		20.3				20.3		0.0
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | COVID-19
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		14.0				14.0		24.9
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Plant Retirement Costs - Asset Retirement Obligation Costs [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		25.9				25.9		25.9
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Storm Related Costs [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		325.8				325.8		134.2
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Asset Retirement Obligation - Louisiana [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		10.0				10.0		9.1
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Other Regulatory Assets Not Yet Being Recovered [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		32.6				32.6		27.4
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | AEP Texas Inc. [Member] | COVID-19
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		3.9				3.9		10.5
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | AEP Texas Inc. [Member] | Storm Related Costs [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		22.7				22.7		0.8
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | AEP Texas Inc. [Member] | Other Regulatory Assets Not Yet Being Recovered [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		5.3				5.3		1.5
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | AEP Texas Inc. [Member] | Texas Retail Electric Provider Bad Debt Expense
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		4.1				4.1		0.0
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | AEP Texas Inc. [Member] | Vegetation Management Programs
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		5.2				5.2		3.8
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Appalachian Power Co [Member] | Plant Retirement Costs - Asset Retirement Obligation Costs [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		25.9				25.9		25.9
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Appalachian Power Co [Member] | Storm Related Costs [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		59.8				59.8		3.4
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Appalachian Power Co [Member] | COVID-19 - West Virginia
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		0.4				0.4		1.5
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Appalachian Power Co [Member] | Other Regulatory Assets Not Yet Being Recovered [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		1.2				1.2		0.0
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Appalachian Power Co [Member] | Environmental Expense Deferral - Virginia
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		0.0				0.0		9.3
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Indiana Michigan Power Co [Member] | COVID-19
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		1.7				1.7		3.8
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Indiana Michigan Power Co [Member] | Other Regulatory Assets Not Yet Being Recovered [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		1.7				1.7		0.0
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Ohio Power Co [Member] | COVID-19
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		1.9				1.9		4.4
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Ohio Power Co [Member] | Storm Related Costs [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		5.5				5.5		4.0
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Ohio Power Co [Member] | Other Regulatory Assets Not Yet Being Recovered [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		0.1				0.1		0.0
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Public Service Co Of Oklahoma [Member] | Storm Related Costs [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		29.3				29.3		15.8
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Public Service Co Of Oklahoma [Member] | Other Regulatory Assets Not Yet Being Recovered [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		0.9				0.9		0.3
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Southwestern Electric Power Co [Member] | Asset Retirement Obligation - Louisiana [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		10.0				10.0		9.1
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Southwestern Electric Power Co [Member] | Other Regulatory Assets Not Yet Being Recovered [Member]
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		19.3				19.3		14.5
Regulatory Assets Currently Not Earning Return [Member] | Regulatory Assets Pending Final Regulatory Approval [Member] | Southwestern Electric Power Co [Member] | Storm Related Costs - Louisiana
Public Utilities, General Disclosures [Line Items]
Regulatory Assets, Noncurrent		$ 155.4				$ 155.4		$ 99.3

[1] Includes ARO related to Sabine and DHLC.

[2] Includes ARO related to asbestos removal.

[3] Includes ARO related to ash disposal facilities.

[4] Includes ARO related to nuclear decommissioning costs for the Cook Plant of $1.85 billion and $1.80 billion as of September 30, 2021 and December 31, 2020, respectively.

[5] Amounts indicated on the statements of cash flows are net of issuance costs and premium or discount and will not tie to the issuance amounts.

[6] Includes Northeastern Plant, Unit 4, which was retired in 2016. Removal of Northeastern Plant, Unit 4, will be performed with Northeastern Plant, Unit 3, after retirement.

[7] Northeastern Plant, Unit 3 is currently being recovered through 2040.

[8] Represents the amount of annual depreciation that has been collected from customers over the prior 12-month period

[9] Dolet Hills Power Station is currently being recovered through 2026 in the Louisiana jurisdiction and through 2046 in the Arkansas and Texas jurisdictions.

[10] Pirkey Power Plant is currently being recovered through 2025 in the Louisiana jurisdiction and through 2045 in the Arkansas and Texas jurisdictions.

[11] Includes Welsh Plant, Unit 2, which was retired in 2016. Removal of Welsh Plant, Unit 2, will be performed with Welsh Plant, Units 1 and 3, after retirement.

[12] Unit 1 is being recovered through 2027 in the Louisiana jurisdiction and through 2037 in the Arkansas and Texas jurisdictions. Unit 3 is being recovered through 2032 in the Louisiana jurisdiction and through 2042 in the Arkansas and Texas jurisdictions.

[13] These costs were deferred as regulatory assets as of September 30, 2021.

[14] PSO and SWEPCo have active fuel clauses that allow for the recovery of prudently incurred fuel and purchased power expenses. However, the recovery of these costs from customers may be extended over longer than usual time periods to mitigate the impact on customer bills. See “Impacts of Severe Winter Weather” section below for additional information.

[15] PSO has an active fuel clause that allows for the recovery of prudently incurred fuel and purchased power expenses. However, the recovery of these costs from customers may be extended over longer than usual time periods to mitigate the impact on customer bills. See “Impacts of Severe Winter Weather” section below for additional information.

[16] SWEPCo’s balance consists of $107 million, $151 million and $175 million related to the Arkansas, Louisiana and Texas jurisdictions, respectively.

[17] SWEPCo has an active fuel clause that allows for the recovery of prudently incurred fuel and purchased power expenses. However, the recovery of these costs from customers may be extended over longer than usual time periods to mitigate the impact on customer bills. See “Impacts of Severe Winter Weather” section below for additional information