Variable Interest Entities (Details) $ in Millions		12 Months Ended
		Dec. 31, 2020 USD ($) MW		Dec. 31, 2019 USD ($)		Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
ASSETS
Current Assets		$ 4,351.5		$ 4,077.8
Net Property, Plant and Equipment		63,901.6		60,138.1
Other Noncurrent Assets		12,504.1		11,676.4
Total Assets		80,757.2		75,892.3		$ 68,802.8
LIABILITIES AND EQUITY
Current Liabilities		9,926.7		10,299.1
Noncurrent Liabilities		50,010.8		45,571.4
Equity		20,774.5		19,913.2		19,059.4	$ 18,313.6
Total Liabilities and Equity		80,757.2		75,892.3
Variable Interest Entities (Textuals)
Securitization Bonds		716.4		1,025.1
Securitized Assets		657.0		858.1
Redeemable Noncontrolling Interest		0.0		65.7
Equity Method Investments		1,406.3		1,356.6
Equity Method Investment Income		91.1		72.1		$ 73.1
Unregulated Operation [Member]
ASSETS
Net Property, Plant and Equipment		1,927.0		1,757.7
Variable Interest Entities (Textuals)
Depreciable Life Ranges - Transmission						40 years
Protected Cell Of Energy Insurance Services, Inc. [Member]
Variable Interest Entities (Textuals)
Insurance Premium Expense to Protected Cell		31.0		34.0		$ 34.0
Protected Cell Of Energy Insurance Services, Inc. [Member] | Variable Interest Entities [Member]
ASSETS
Current Assets		198.1		194.6
Net Property, Plant and Equipment		0.0		0.0
Other Noncurrent Assets		0.0		0.0
Total Assets		198.1		194.6
LIABILITIES AND EQUITY
Current Liabilities		43.1		40.7
Noncurrent Liabilities		62.5		78.0
Equity		92.5		75.9
Total Liabilities and Equity		$ 198.1		194.6
Transource Energy [Member]
Variable Interest Entities (Textuals)
Debt-to-Total Capitalization Maximum		67.50%
Transource Energy [Member] | Variable Interest Entities [Member]
ASSETS
Current Assets		$ 22.2		25.8
Net Property, Plant and Equipment		458.7		424.1
Other Noncurrent Assets		3.7		3.2
Total Assets		484.6		453.1
LIABILITIES AND EQUITY
Current Liabilities		32.6		192.4
Noncurrent Liabilities		185.0		4.8
Equity		267.0		255.9
Total Liabilities and Equity		$ 484.6		453.1
Trent and Desert Sky Wind Farms [Member]
Variable Interest Entities (Textuals)
Non-Affiliate Interest		20.10%
AEP Ownership in LLCs		79.90%
Desert Sky and Trent PPA Period		12 years
Redeemable Noncontrolling Interest		$ 0.0		66.0
Trent and Desert Sky Wind Farms [Member] | Variable Interest Entities [Member]
ASSETS
Current Assets				7.8
Net Property, Plant and Equipment				330.6
Other Noncurrent Assets				10.1
Total Assets				348.5
LIABILITIES AND EQUITY
Current Liabilities				5.5
Noncurrent Liabilities				15.8
Equity				327.2
Total Liabilities and Equity				348.5
Apple Blossom and Black Oak [Member]
Variable Interest Entities (Textuals)
Noncontrolling Interest in Variable Interest Entity		119.0		128.0
HLBV Income for Noncontrolling Interests		6.0		6.0
Apple Blossom and Black Oak [Member] | Variable Interest Entities [Member]
ASSETS
Current Assets		9.6		10.1
Net Property, Plant and Equipment		223.1		231.4
Other Noncurrent Assets		12.1		13.1
Total Assets		244.8		254.6
LIABILITIES AND EQUITY
Current Liabilities		5.3		5.4
Noncurrent Liabilities		4.9		4.7
Equity		234.6		244.5
Total Liabilities and Equity		244.8		254.6
Santa Rita East [Member]
Variable Interest Entities (Textuals)
Noncontrolling Interest in Variable Interest Entity		$ 61.0		118.0
Percentage of an Asset Acquired		85.00%
Production Tax Credits		$ 23.0		10.0
Santa Rita East [Member] | Variable Interest Entities [Member]
ASSETS
Current Assets		6.0		17.7
Net Property, Plant and Equipment		453.1		465.2
Other Noncurrent Assets		0.0		0.3
Total Assets		459.1		483.2
LIABILITIES AND EQUITY
Current Liabilities		3.5		3.9
Noncurrent Liabilities		6.7		7.5
Equity		448.9		471.8
Total Liabilities and Equity		$ 459.1		483.2
Santa Rita East [Member] | Initial Interest Acquired [Member]
Variable Interest Entities (Textuals)
Percentage of an Asset Acquired		75.00%
Santa Rita East [Member] | Additional 10 Percent [Member]
Variable Interest Entities (Textuals)
Percentage of an Asset Acquired		10.00%
AEP Credit, Inc.
Variable Interest Entities (Textuals)
Minimum Percentage of Equity AEP Provides		5.00%
Percentage Of Short Term Borrowing Needs In Excess Of Third Party Financings		25.00%
AEP Credit, Inc. | Variable Interest Entities [Member]
ASSETS
Current Assets		$ 960.4		842.8
Net Property, Plant and Equipment		0.0		0.0
Other Noncurrent Assets		12.9		7.1
Total Assets		973.3		849.9
LIABILITIES AND EQUITY
Current Liabilities		827.2		805.2
Noncurrent Liabilities		0.8		0.9
Equity		145.3		43.8
Total Liabilities and Equity		973.3		849.9
Dolet Hills Lignite Co, LLC [Member]
Variable Interest Entities (Textuals)
Equity Method Investment Income		$ 2.9		3.0		2.7
Ohio Valley Electric Corporation [Member]
Variable Interest Entities (Textuals)
AEP's Ownership In OVEC		43.47%
Approximate OVEC Generating Capacity (MWs) | MW		2,400
Intercompany Power Agreement End Date		2040
Outstanding Indebtedness		$ 1,300.0		1,400.0
Capital Contribution From Parent [Member] | Ohio Valley Electric Corporation [Member]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures
As Reported on the Balance Sheet		4.4		4.4
Maximum Exposure		4.4		4.4
Retained Earnings [Member]
LIABILITIES AND EQUITY
Equity		10,687.8		9,900.9		9,325.3	8,626.7
AEP's Ratio of OVEC Debt [Member] | Ohio Valley Electric Corporation [Member]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures
As Reported on the Balance Sheet		0.0		0.0
Maximum Exposure	[1]	555.0		588.9
Total Investment [Member] | Ohio Valley Electric Corporation [Member]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures
As Reported on the Balance Sheet		4.4		4.4
Maximum Exposure		559.4		593.3
Non-Affiliate Contribution [Member] | Trent and Desert Sky Wind Farms [Member] | Variable Interest Entities [Member]
ASSETS
Net Property, Plant and Equipment		$ 84.0
Total Generation MWs [Member] | Santa Rita East [Member]
Variable Interest Entities (Textuals)
WindGenerationMWs | MW		302
Long-term PPA MWs [Member] | Santa Rita East [Member]
Variable Interest Entities (Textuals)
WindGenerationMWs | MW		260
Sold at Wholesale MWs [Member] | Santa Rita East [Member]
Variable Interest Entities (Textuals)
WindGenerationMWs | MW		42
Parent Company [Member] | Ohio Valley Electric Corporation [Member]
Variable Interest Entities (Textuals)
AEP's Ownership In OVEC		39.17%
Great Plains Energy Inc. [Member] | Transource Energy [Member]
Variable Interest Entities (Textuals)
Equity and Voting Ownership Percentage		13.50%
Cleco Power, LLC [Member]
Variable Interest Entities (Textuals)
Percentage of VIE Sales of Lignite Produced		50.00%
AEP Transmission Co [Member]
ASSETS
Current Assets		$ 235.8		197.4
Net Property, Plant and Equipment		10,772.8		9,490.9
Other Noncurrent Assets		237.4		202.5
Total Assets		11,246.0		9,890.8		8,394.1
LIABILITIES AND EQUITY
Current Liabilities		1,137.5		1,093.1
Noncurrent Liabilities		5,395.6		4,788.2
Total Liabilities and Equity		11,246.0		9,890.8
AEP Transmission Co [Member] | Unregulated Operation [Member]
ASSETS
Net Property, Plant and Equipment		0.7		1.4
AEP Transmission Co [Member] | Billings from AEP Service Corporation [Member]
Variable Interest Entities (Textuals)
Billings from VIE		270.3		242.3		220.4
AEP Transmission Co [Member] | Carrying Amount in AEP Service Corporation's Accounts Payable [Member]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures
As Reported on the Balance Sheet		45.9		33.4
Maximum Exposure		45.9		33.4
Appalachian Power Co [Member]
ASSETS
Current Assets		674.1		700.6
Net Property, Plant and Equipment		11,394.1		11,081.9
Other Noncurrent Assets		1,247.0		985.8
Total Assets		13,315.2		12,768.3
LIABILITIES AND EQUITY
Current Liabilities		1,217.7		1,226.0
Noncurrent Liabilities		7,753.2		7,369.9
Equity		4,344.3		4,172.4		4,006.1	3,804.5
Total Liabilities and Equity		13,315.2		12,768.3
Variable Interest Entities (Textuals)
Securitization Bonds		223.8		248.3
Securitized Assets		210.1		234.7
Amount Of Power Purchased From OVEC		94.4		104.5		100.4
Appalachian Power Co [Member] | Unregulated Operation [Member]
ASSETS
Net Property, Plant and Equipment		24.0		22.6
Appalachian Power Co [Member] | Appalachian Consumer Rate Relief Funding [Member]
Variable Interest Entities (Textuals)
Securitized Assets		210.0		235.0
Appalachian Power Co [Member] | Appalachian Consumer Rate Relief Funding [Member] | Variable Interest Entities [Member]
ASSETS
Current Assets		16.8		21.5
Net Property, Plant and Equipment		0.0		0.0
Other Noncurrent Assets		212.7	[2]	237.5	[3]
Total Assets		229.5		259.0
LIABILITIES AND EQUITY
Current Liabilities		28.7		28.3
Noncurrent Liabilities		198.9		228.8
Equity		1.9		1.9
Total Liabilities and Equity		$ 229.5		259.0
Appalachian Power Co [Member] | Ohio Valley Electric Corporation [Member]
Variable Interest Entities (Textuals)
Power Participation Ratio		15.69%
Outstanding Indebtedness		$ 200.0		213.0
Appalachian Power Co [Member] | Billings from AEP Service Corporation [Member]
Variable Interest Entities (Textuals)
Billings from VIE		294.9		308.3		295.6
Appalachian Power Co [Member] | Carrying Amount in AEP Service Corporation's Accounts Payable [Member]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures
As Reported on the Balance Sheet		42.8		44.1
Maximum Exposure		42.8		44.1
Appalachian Power Co [Member] | Retained Earnings [Member]
LIABILITIES AND EQUITY
Equity		2,248.0		2,078.3		1,922.0	1,714.1
Appalachian Power Co [Member] | Other Noncurrent Assets [Member] | Appalachian Consumer Rate Relief Funding [Member]
Variable Interest Entities (Textuals)
Intercompany Item Eliminated in Consolidation		3.0		3.0
Appalachian Power Co [Member] | Current Liabilities [Member] | Appalachian Consumer Rate Relief Funding [Member]
Variable Interest Entities (Textuals)
Securitization Bonds		25.0		25.0
Appalachian Power Co [Member] | Noncurrent Liabilities [Member] | Appalachian Consumer Rate Relief Funding [Member]
Variable Interest Entities (Textuals)
Securitization Bonds		199.0		223.0
Indiana Michigan Power Co [Member]
ASSETS
Current Assets		418.8		403.0
Net Property, Plant and Equipment		7,052.3		6,899.7
Other Noncurrent Assets		4,167.2		3,934.7
Total Assets		11,638.3		11,237.4
LIABILITIES AND EQUITY
Current Liabilities		1,104.5		883.4
Noncurrent Liabilities		7,784.6		7,809.6
Equity		2,749.2		2,544.4		2,352.8	2,217.6
Total Liabilities and Equity		11,638.3		11,237.4
Variable Interest Entities (Textuals)
Amount Of Power Purchased From OVEC		47.2		52.3		50.2
Indiana Michigan Power Co [Member] | Unregulated Operation [Member]
ASSETS
Net Property, Plant and Equipment		28.2		28.8
Indiana Michigan Power Co [Member] | DCC Fuel [Member]
Variable Interest Entities (Textuals)
Payments Made by I&M to DCC Fuel		94.0		95.0		113.0
Indiana Michigan Power Co [Member] | DCC Fuel [Member] | Variable Interest Entities [Member]
ASSETS
Current Assets		76.1		86.5
Net Property, Plant and Equipment		138.9		156.8
Other Noncurrent Assets		70.9		82.5
Total Assets		285.9		325.8
LIABILITIES AND EQUITY
Current Liabilities		76.0		86.4
Noncurrent Liabilities		209.9		239.4
Equity		0.0		0.0
Total Liabilities and Equity		$ 285.9		325.8
Indiana Michigan Power Co [Member] | Ohio Valley Electric Corporation [Member]
Variable Interest Entities (Textuals)
Power Participation Ratio		7.85%
Outstanding Indebtedness		$ 100.0		106.0
Indiana Michigan Power Co [Member] | Billings from AEP Service Corporation [Member]
Variable Interest Entities (Textuals)
Billings from VIE		210.2		184.8		173.5
Indiana Michigan Power Co [Member] | Carrying Amount in AEP Service Corporation's Accounts Payable [Member]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures
As Reported on the Balance Sheet		27.1		28.6
Maximum Exposure		27.1		28.6
Indiana Michigan Power Co [Member] | Billings from AEP Generating Company [Member]
Variable Interest Entities (Textuals)
Billings from VIE		173.0		215.0		238.0
Indiana Michigan Power Co [Member] | Carrying Amount in AEP Generating Company's Accounts Payable [Member]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures
As Reported on the Balance Sheet		$ 9.0		10.0
Indiana Michigan Power Co [Member] | Rockport Generating Plant (Unit No. 1) [Member]
Variable Interest Entities (Textuals)
Jointly Owned Utility Plant, Proportionate Ownership Share		50.00%
Indiana Michigan Power Co [Member] | Retained Earnings [Member]
LIABILITIES AND EQUITY
Equity		$ 1,718.7		1,518.5		1,329.1	1,192.2
Ohio Power Co [Member]
ASSETS
Current Assets		256.3		238.5
Net Property, Plant and Equipment		7,452.1		6,907.0
Other Noncurrent Assets		1,002.0		898.1
Total Assets		8,710.4		8,043.6
LIABILITIES AND EQUITY
Current Liabilities		1,906.2		1,297.9
Noncurrent Liabilities		4,111.5		4,237.2
Equity		2,692.7		2,508.5		2,297.4	2,310.3
Total Liabilities and Equity		8,710.4		8,043.6
Variable Interest Entities (Textuals)
Amount Of Power Purchased From OVEC		120.8		132.7		127.5
Ohio Power Co [Member] | Unregulated Operation [Member]
ASSETS
Net Property, Plant and Equipment		$ 9.9		9.8
Ohio Power Co [Member] | Ohio Valley Electric Corporation [Member]
Variable Interest Entities (Textuals)
AEP's Ownership In OVEC		4.30%
Power Participation Ratio		19.93%
Outstanding Indebtedness		$ 255.0		270.0
Ohio Power Co [Member] | Billings from AEP Service Corporation [Member]
Variable Interest Entities (Textuals)
Billings from VIE		232.8		230.4		214.9
Ohio Power Co [Member] | Carrying Amount in AEP Service Corporation's Accounts Payable [Member]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures
As Reported on the Balance Sheet		33.9		33.2
Maximum Exposure		33.9		33.2
Ohio Power Co [Member] | Retained Earnings [Member]
LIABILITIES AND EQUITY
Equity		1,532.7		1,348.5		1,136.4	1,148.4
Public Service Co Of Oklahoma [Member]
ASSETS
Current Assets		181.3		188.2
Net Property, Plant and Equipment		4,320.0		4,103.3
Other Noncurrent Assets		489.4		460.0
Total Assets		4,990.7		4,751.5
LIABILITIES AND EQUITY
Current Liabilities		478.6		445.8
Noncurrent Liabilities		2,966.5		2,932.4
Equity		1,545.6		1,373.3		1,248.0	1,215.3
Total Liabilities and Equity		4,990.7		4,751.5
Public Service Co Of Oklahoma [Member] | Unregulated Operation [Member]
ASSETS
Net Property, Plant and Equipment		6.9		4.7
Public Service Co Of Oklahoma [Member] | Billings from AEP Service Corporation [Member]
Variable Interest Entities (Textuals)
Billings from VIE		113.2		125.7		121.5
Public Service Co Of Oklahoma [Member] | Carrying Amount in AEP Service Corporation's Accounts Payable [Member]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures
As Reported on the Balance Sheet		15.7		18.1
Maximum Exposure		15.7		18.1
Public Service Co Of Oklahoma [Member] | Retained Earnings [Member]
LIABILITIES AND EQUITY
Equity		974.3		851.0		724.7	691.5
Southwestern Electric Power Co [Member]
ASSETS
Current Assets		428.0		354.1
Net Property, Plant and Equipment		7,088.2		7,095.2
Other Noncurrent Assets		637.9		382.9
Total Assets		8,154.1		7,832.2
LIABILITIES AND EQUITY
Current Liabilities		763.6		674.7
Noncurrent Liabilities		4,762.8		4,716.4
Equity		2,627.7		2,441.1		2,315.6	2,234.5
Total Liabilities and Equity		8,154.1		7,832.2
Variable Interest Entities (Textuals)
Equity Method Investment Income		2.9		3.0		2.7
Southwestern Electric Power Co [Member] | Unregulated Operation [Member]
ASSETS
Net Property, Plant and Equipment		97.8		112.1
Southwestern Electric Power Co [Member] | Sabine Mining Co [Member]
Variable Interest Entities (Textuals)
Billings from VIE		131.0		110.0		152.0
Guarantees Of Mine Reclamation Amount		155.0
Estimated Final Cost Mine Reclamation		104.0
Amount Collected, Rider Mine Close Other Assets Noncurrent		8.0
Amount Collected Through Rider For Final Mine Closure And Reclamation Costs		81.0
Amount Collected, Rider Mine Close ARO Noncurrent		89.0
Southwestern Electric Power Co [Member] | Sabine Mining Co [Member] | Variable Interest Entities [Member]
ASSETS
Current Assets		88.0		80.0
Net Property, Plant and Equipment		97.3		111.6
Other Noncurrent Assets		99.3		93.2
Total Assets		284.6		284.8
LIABILITIES AND EQUITY
Current Liabilities		57.7		50.6
Noncurrent Liabilities		225.3		233.6
Equity		1.6		0.6
Total Liabilities and Equity		284.6		284.8
Southwestern Electric Power Co [Member] | Dolet Hills Lignite Co, LLC [Member]
Variable Interest Entities (Textuals)
Billings from VIE		$ 142.0		55.0		58.0
Percentage of VIE Sales of Lignite Produced		50.00%
Percentage of DHLCs Debt Guaranteed by Each SWEPCo and CLECO		50.00%
Percentage of Management Fee Received by SWEPCo from DHLC		100.00%
Equity Method Investment Income		$ 2.9		3.0		2.7
Southwestern Electric Power Co [Member] | Billings from AEP Service Corporation [Member]
Variable Interest Entities (Textuals)
Billings from VIE		161.8		169.5		164.4
Southwestern Electric Power Co [Member] | Carrying Amount in AEP Service Corporation's Accounts Payable [Member]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures
As Reported on the Balance Sheet		22.0		23.4
Maximum Exposure		22.0		23.4
Southwestern Electric Power Co [Member] | Capital Contribution From Parent [Member] | Dolet Hills Lignite Co, LLC [Member]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures
As Reported on the Balance Sheet		7.6		7.6
Maximum Exposure		7.6		7.6
Southwestern Electric Power Co [Member] | Retained Earnings [Member]
LIABILITIES AND EQUITY
Equity		1,811.9		1,629.5		1,508.4	1,426.6
Southwestern Electric Power Co [Member] | Retained Earnings [Member] | Dolet Hills Lignite Co, LLC [Member]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures
As Reported on the Balance Sheet		20.4		17.5
Maximum Exposure		20.4		17.5
Southwestern Electric Power Co [Member] | SWEPCo's Share of Obligations [Member] | Dolet Hills Lignite Co, LLC [Member]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures
As Reported on the Balance Sheet		0.0		0.0
Maximum Exposure		98.5		130.0
Southwestern Electric Power Co [Member] | Total Investment [Member] | Dolet Hills Lignite Co, LLC [Member]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures
As Reported on the Balance Sheet		28.0		25.1
Maximum Exposure		$ 126.5		155.1
AEP Generating Co [Member] | Rockport Generating Plant (Unit No. 1) [Member]
Variable Interest Entities (Textuals)
Jointly Owned Utility Plant, Proportionate Ownership Share		50.00%
AEP Generating Co [Member] | Rockport Generating Plant (Unit No. 2) [Member]
Variable Interest Entities (Textuals)
Percentage Interest in Lease		50.00%
Transource Energy [Member]
Variable Interest Entities (Textuals)
Equity and Voting Ownership Percentage		86.50%
AEP Texas Inc. [Member]
ASSETS
Current Assets		$ 310.9		692.9
Net Property, Plant and Equipment		9,813.6		8,845.1
Other Noncurrent Assets		905.7		1,051.1
Total Assets		11,030.2		10,589.1
LIABILITIES AND EQUITY
Current Liabilities		676.8		1,027.2
Noncurrent Liabilities		7,147.4		6,600.8
Equity		3,206.0		2,961.1		2,580.5	2,169.9
Total Liabilities and Equity		11,030.2		10,589.1
Variable Interest Entities (Textuals)
Securitization Bonds		492.6		776.8
Securitized Assets		$ 446.8		623.4
Jointly Owned Utility Plant, Proportionate Ownership Share		54.69%
Accumulated Provisions For Rate Refunds		$ 20.1		64.7
AEP Texas Inc. [Member] | Unregulated Operation [Member]
ASSETS
Net Property, Plant and Equipment		1.2		61.1
AEP Texas Inc. [Member] | AEP Texas Central Transition Funding Co [Member]
Variable Interest Entities (Textuals)
Securitized Assets		242.0		389.0
AEP Texas Inc. [Member] | AEP Texas Central Transition Funding Co [Member] | Variable Interest Entities [Member]
ASSETS
Current Assets		61.2		187.0
Net Property, Plant and Equipment		0.0		0.0
Other Noncurrent Assets		273.9	[4]	428.1	[5]
Total Assets		335.1		615.1
LIABILITIES AND EQUITY
Current Liabilities		69.8		280.2
Noncurrent Liabilities		246.5		316.3
Equity		18.8		18.6
Total Liabilities and Equity		335.1		615.1
AEP Texas Inc. [Member] | Restoration Funding [Member]
Variable Interest Entities (Textuals)
Securitized Assets		205.0		232.0
AEP Texas Inc. [Member] | Restoration Funding [Member] | Variable Interest Entities [Member]
ASSETS
Current Assets		23.3		9.4
Net Property, Plant and Equipment		0.0		0.0
Other Noncurrent Assets		214.9	[6]	234.4	[7]
Total Assets		238.2		243.8
LIABILITIES AND EQUITY
Current Liabilities		33.9		16.3
Noncurrent Liabilities		203.1		226.3
Equity		1.2		1.2
Total Liabilities and Equity		238.2		243.8
AEP Texas Inc. [Member] | Billings from AEP Service Corporation [Member]
Variable Interest Entities (Textuals)
Billings from VIE		199.4		206.6		184.3
AEP Texas Inc. [Member] | Carrying Amount in AEP Service Corporation's Accounts Payable [Member]
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures
As Reported on the Balance Sheet		30.5		32.4
Maximum Exposure		30.5		32.4
AEP Texas Inc. [Member] | Retained Earnings [Member]
LIABILITIES AND EQUITY
Equity		1,757.0		1,516.0		1,337.7	$ 1,124.6
AEP Texas Inc. [Member] | Other Noncurrent Assets [Member] | AEP Texas Central Transition Funding Co [Member]
Variable Interest Entities (Textuals)
Intercompany Item Eliminated in Consolidation		32.0		39.0
AEP Texas Inc. [Member] | Other Noncurrent Assets [Member] | Restoration Funding [Member]
Variable Interest Entities (Textuals)
Intercompany Item Eliminated in Consolidation		9.0		1.0
AEP Texas Inc. [Member] | Current Liabilities [Member] | AEP Texas Central Transition Funding Co [Member]
Variable Interest Entities (Textuals)
Securitization Bonds		66.0		267.0
AEP Texas Inc. [Member] | Current Liabilities [Member] | Restoration Funding [Member]
Variable Interest Entities (Textuals)
Securitization Bonds		23.0		14.0
AEP Texas Inc. [Member] | Noncurrent Liabilities [Member] | AEP Texas Central Transition Funding Co [Member]
Variable Interest Entities (Textuals)
Securitization Bonds		209.0		274.0
AEP Texas Inc. [Member] | Noncurrent Liabilities [Member] | Restoration Funding [Member]
Variable Interest Entities (Textuals)
Securitization Bonds		$ 195.0		221.0
Joint Venture Wind Farms [Member]
Variable Interest Entities (Textuals)
Equity Method Investment, Ownership Percentage		50.00%
Production Tax Credits		$ 36.0		27.0
Equity Method Investments		376.0		394.0
Historical Investment Balance		399.0
Historical Investment Basis Difference		(12.0)
Equity Method Investment Income		$ 2.0		4.0
Berkshire Hathaway [Member]
Variable Interest Entities (Textuals)
Equity Method Investment, Ownership Percentage		50.00%
AEP Transmission Holdco [Member]
Variable Interest Entities (Textuals)
Equity Method Investment, Ownership Percentage		50.00%
BP Wind Energy [Member]
Variable Interest Entities (Textuals)
Equity Method Investment, Ownership Percentage		50.00%
ETT [Member]
Variable Interest Entities (Textuals)
Equity Method Investments		$ 732.0		695.0
Equity Method Investment Income		$ 68.0		$ 66.0		$ 62.0

[1] Based on the Registrants’ power participation ratios APCo, I&M and OPCo’s share of OVEC debt was $200 million, $100 million and $255 million as of December 31, 2020 and $213 million, $106 million and $270 million as of December 31, 2019, respectively.

[2] Includes an intercompany item eliminated in consolidation of $3 million.

[3] Includes an intercompany item eliminated in consolidation of $3 million.

[4] Includes an intercompany item eliminated in consolidation of $32 million.

[5] Includes an intercompany item eliminated in consolidation of $39 million.

[6] Includes an intercompany item eliminated in consolidation of $9 million.

[7] Includes an intercompany item eliminated in consolidation of $1 million.