Business Segments (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2021		Dec. 31, 2020		Dec. 31, 2019
Reportable Segment Information
Revenue from Contracts with Customers		$ 16,792.0		$ 14,918.5		$ 15,561.4
Sales to AEP Affiliates		0.0		0.0		0.0
Total Revenues		16,792.0		14,918.5		15,561.4
Asset Impairments and Other Related Charges		11.6		0.0		156.4
Utilities Operating Expense, Depreciation and Amortization		2,825.7		2,682.8		2,514.5
Allowance for Equity Funds Used During Construction		139.7		148.1		168.4
Interest Expense		1,199.1		1,165.7		1,072.5
Income Tax Expense (Benefit)		115.5		40.5		(12.9)
Equity Earnings (Loss) of Unconsolidated Subsidiaries		91.7		91.1		72.1
Net Income (Loss)		2,488.1		2,196.7		1,919.8
Gross Property Additions		6,426.8		6,246.3		6,969.8
Balance Sheet Information
Property, Plant and Equipment, Gross, Period Increase (Decrease)		86,806.4		84,313.0
Accumulated Depreciation and Amortization		20,805.1		20,411.4
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		66,001.3	[1]	63,901.6
Total Assets		87,668.7	[2]	80,757.2		75,892.3
Investments in Equity Method Investees		1,447.5		1,406.3		1,356.6
Affiliated Long Term Debt Current						0.0
Long-term Debt Due Within One Year		2,153.8		2,086.1		1,598.7
Long-term Debt - Affiliated		0.0		0.0		0.0
Long-term Debt		31,300.7		28,986.4		25,126.8
Total Long-term Debt Outstanding		33,454.5	[3],[4],[5]	31,072.5		26,725.5
AEP Transmission Co [Member]
Reportable Segment Information
Revenue from Contracts with Customers		1,410.9		1,232.7		1,042.1
Sales to AEP Affiliates		1,153.9		896.3		806.7
Total Revenues		1,469.3		1,145.7		1,021.4
Utilities Operating Expense, Depreciation and Amortization		297.3		249.0		176.0
Interest Income		0.5		2.4		3.0
Allowance for Equity Funds Used During Construction		67.2		74.0		84.3
Interest Expense		141.2		127.8		97.4
Income Tax Expense (Benefit)		144.1		106.7		117.4
Net Income (Loss)		591.7		423.4		439.7
Gross Property Additions		1,442.7		1,621.9		1,419.5
Balance Sheet Information
Property, Plant and Equipment, Gross, Period Increase (Decrease)		12,708.5		11,345.6
Accumulated Depreciation and Amortization		772.8		572.8
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		11,935.7	[1]	10,772.8
Notes Receivable, Related Parties		0.0		0.0
Total Assets		12,524.4	[6]	11,246.0		9,890.8
Long-term Debt Due Within One Year		104.0		50.0
Long-term Debt		4,239.9		3,898.5
Total Long-term Debt Outstanding		4,343.9		3,948.5		3,427.3
Vertically Integrated Utilities [Member]
Reportable Segment Information
Revenue from Contracts with Customers		9,852.2		8,753.2		9,245.7
Transmission and Distribution Utilities Revenues [Member]
Reportable Segment Information
Revenue from Contracts with Customers		4,464.1		4,238.7		4,319.0
Transmission [Member] | AEP Transmission Co [Member]
Reportable Segment Information
Revenue from Contracts with Customers		315.1		248.8		214.6
Generation and Marketing Revenues [Member]
Reportable Segment Information
Revenue from Contracts with Customers		2,108.3		1,621.0		1,721.8
Other Revenues [Member]
Reportable Segment Information
Revenue from Contracts with Customers		367.4		305.6		274.9
Total Revenues		227.6	[7],[8]	61.5	[9],[10]	61.7	[11],[12]
Other Revenues [Member] | AEP Transmission Co [Member]
Reportable Segment Information
Revenue from Contracts with Customers		0.3		0.6		0.1
Total Revenues		0.0	[13]	0.0	[14]	0.0	[15]
Reconciling Adjustments [Member]
Reportable Segment Information
Revenue from Contracts with Customers		0.0		0.0		0.0
Sales to AEP Affiliates		(1,461.5)		(1,328.0)		(1,314.8)
Total Revenues		(1,461.5)		(1,328.0)		(1,314.8)
Asset Impairments and Other Related Charges		0.0				0.0
Utilities Operating Expense, Depreciation and Amortization		0.0		0.0		24.5	[16]
Interest Expense		(18.7)		(42.1)		(66.1)	[16]
Income Tax Expense (Benefit)		0.0		0.0		0.0
Equity Earnings (Loss) of Unconsolidated Subsidiaries		0.0		0.0		0.0
Net Income (Loss)		0.0		0.0		0.0
Gross Property Additions		(29.2)		(15.3)		(20.4)
Balance Sheet Information
Property, Plant and Equipment, Gross, Period Increase (Decrease)		0.0		0.0
Accumulated Depreciation and Amortization		0.0		0.0
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		0.0		0.0
Total Assets	[17]	(4,409.1)		(3,961.7)		(3,801.3)	[16]
Investments in Equity Method Investees		0.0		0.0		0.0
Affiliated Long Term Debt Current						(20.0)
Long-term Debt Due Within One Year		0.0		0.0		0.0
Long-term Debt - Affiliated		(65.0)		(65.0)		(39.0)
Long-term Debt		0.0		0.0		0.0
Total Long-term Debt Outstanding		(65.0)		(65.0)		(59.0)
Reconciling Adjustments [Member] | AEP Transmission Co [Member]
Reportable Segment Information
Revenue from Contracts with Customers		0.0		0.0		0.0
Sales to AEP Affiliates		0.0		0.0		0.0
Total Revenues		0.0		0.0		0.0
Utilities Operating Expense, Depreciation and Amortization		0.0		0.0		0.0
Interest Income	[18]	(157.7)		(148.1)		(122.1)
Allowance for Equity Funds Used During Construction		0.0		0.0		0.0
Interest Expense	[18]	(157.7)		(148.1)		(122.1)
Income Tax Expense (Benefit)		0.0		0.0		0.0
Net Income (Loss)		0.0		0.0		0.0
Gross Property Additions		0.0		0.0		0.0
Balance Sheet Information
Property, Plant and Equipment, Gross, Period Increase (Decrease)		0.0		0.0
Accumulated Depreciation and Amortization		0.0		0.0
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		0.0		0.0
Notes Receivable, Related Parties	[19]	(4,343.9)		(3,948.5)
Total Assets	[20]	(4,429.4)	[6]	(4,023.1)		(3,493.3)
Total Long-term Debt Outstanding	[19]	(4,390.0)		(3,990.0)		(3,465.0)
Reconciling Adjustments [Member] | Other Revenues [Member]
Reportable Segment Information
Total Revenues		(10.7)	[7],[8]	(74.9)	[9],[10]	(139.3)	[11],[12]
Reconciling Adjustments [Member] | Other Revenues [Member] | AEP Transmission Co [Member]
Reportable Segment Information
Revenue from Contracts with Customers		0.0		0.0		0.0
Vertically Integrated Utilities [Member]
Reportable Segment Information
Sales to AEP Affiliates		146.3		126.2		121.4
Total Revenues		9,998.5		8,879.4		9,367.1
Asset Impairments and Other Related Charges		11.6				92.9
Utilities Operating Expense, Depreciation and Amortization		1,747.6		1,600.5		1,447.0
Interest Expense		574.2		565.0		568.3
Income Tax Expense (Benefit)		(11.2)		(7.0)		(97.7)
Equity Earnings (Loss) of Unconsolidated Subsidiaries		3.4		2.9		3.0
Net Income (Loss)		1,116.7		1,064.5		985.6
Gross Property Additions		2,963.1		2,291.2		2,437.4
Balance Sheet Information
Property, Plant and Equipment, Gross, Period Increase (Decrease)		48,368.9		49,023.3
Accumulated Depreciation and Amortization		15,471.6		15,586.2
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		32,897.3		33,437.1
Total Assets		46,974.2	[2]	42,752.7		41,228.8
Investments in Equity Method Investees		33.5		37.1		41.7
Affiliated Long Term Debt Current						20.0
Long-term Debt Due Within One Year		1,022.4		1,034.6		704.7
Long-term Debt - Affiliated		65.0		65.0		39.0
Long-term Debt		12,964.4		12,375.6		12,162.0
Total Long-term Debt Outstanding		14,051.8		13,475.2		12,925.7
Vertically Integrated Utilities [Member] | Vertically Integrated Utilities [Member]
Reportable Segment Information
Revenue from Contracts with Customers		9,852.2		8,753.2		9,245.7
Vertically Integrated Utilities [Member] | Other Revenues [Member]
Reportable Segment Information
Total Revenues		(0.5)	[7],[8]	0.0	[9],[10]	0.0	[11],[12]
Transmission and Distribution Companies [Member]
Reportable Segment Information
Sales to AEP Affiliates		28.8		107.2		163.5
Total Revenues		4,492.9		4,345.9		4,482.5
Asset Impairments and Other Related Charges		0.0				32.5
Utilities Operating Expense, Depreciation and Amortization		690.3		751.1		789.5
Interest Expense		300.9		289.2		243.3
Income Tax Expense (Benefit)		77.5		29.7		(25.2)
Equity Earnings (Loss) of Unconsolidated Subsidiaries		0.0		0.0		0.0
Net Income (Loss)		543.4		496.4		451.0
Gross Property Additions		1,766.0		2,108.1		2,074.3
Balance Sheet Information
Property, Plant and Equipment, Gross, Period Increase (Decrease)		22,700.7		21,145.0
Accumulated Depreciation and Amortization		4,102.4		3,879.3
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		18,598.3		17,265.7
Total Assets		21,120.2		19,765.9		18,757.5
Investments in Equity Method Investees		2.5		2.1		2.5
Affiliated Long Term Debt Current						0.0
Long-term Debt Due Within One Year		716.1		588.8		392.2
Long-term Debt - Affiliated		0.0		0.0		0.0
Long-term Debt		7,433.2		6,661.9		6,248.1
Total Long-term Debt Outstanding		8,149.3		7,250.7		6,640.3
Transmission and Distribution Companies [Member] | Transmission and Distribution Utilities Revenues [Member]
Reportable Segment Information
Revenue from Contracts with Customers		4,464.1		4,238.7		4,319.0
Transmission and Distribution Companies [Member] | Other Revenues [Member]
Reportable Segment Information
Total Revenues		19.0	[7],[8]	83.0	[9],[10]	150.0	[11],[12]
AEP Transmission Holdco
Reportable Segment Information
Sales to AEP Affiliates		1,175.1		901.4		813.0
Total Revenues		1,526.2		1,198.8		1,073.2
Asset Impairments and Other Related Charges		0.0				0.0
Utilities Operating Expense, Depreciation and Amortization		306.0		257.6		183.4
Interest Expense		146.3		133.2		103.3
Income Tax Expense (Benefit)		159.6		130.8		136.2
Equity Earnings (Loss) of Unconsolidated Subsidiaries		75.0		82.4		72.8
Net Income (Loss)		682.0		508.5		520.1
Gross Property Additions		1,468.6		1,649.3		1,458.9
Balance Sheet Information
Property, Plant and Equipment, Gross, Period Increase (Decrease)		13,213.0		11,827.2
Accumulated Depreciation and Amortization		801.8		595.7
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		12,411.2		11,231.5
Total Assets		13,873.3	[2]	12,627.3		11,143.5
Investments in Equity Method Investees		830.4		831.3		787.5
Affiliated Long Term Debt Current						0.0
Long-term Debt Due Within One Year		106.4		52.3		0.0
Long-term Debt - Affiliated		0.0		0.0		0.0
Long-term Debt		4,442.7		4,075.7		3,593.8
Total Long-term Debt Outstanding		4,549.1		4,128.0		3,593.8
AEP Transmission Holdco | Transmission [Member]
Reportable Segment Information
Revenue from Contracts with Customers		351.1		297.4		260.2
Generation and Marketing [Member]
Reportable Segment Information
Sales to AEP Affiliates		55.4		104.6		135.8
Total Revenues		2,163.7		1,725.6		1,857.6
Asset Impairments and Other Related Charges		0.0				31.0
Utilities Operating Expense, Depreciation and Amortization		80.9		72.8		69.5
Interest Expense		15.6		24.0		30.0
Income Tax Expense (Benefit)		(48.8)		(108.0)		(53.8)
Equity Earnings (Loss) of Unconsolidated Subsidiaries		(10.6)		3.2		(3.8)
Net Income (Loss)		210.2		216.9		104.1
Gross Property Additions		232.8		197.0		1,005.1
Balance Sheet Information
Property, Plant and Equipment, Gross, Period Increase (Decrease)		2,105.4		1,910.2
Accumulated Depreciation and Amortization		241.0		166.1
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		1,864.4		1,744.1
Total Assets		4,263.6		3,585.9		3,123.8
Investments in Equity Method Investees		487.8		467.0		459.5
Affiliated Long Term Debt Current						0.0
Long-term Debt Due Within One Year		0.0		0.0		0.0
Long-term Debt - Affiliated		0.0		0.0		0.0
Long-term Debt		0.0		0.0		0.0
Total Long-term Debt Outstanding		0.0		0.0		0.0
Generation and Marketing [Member] | Generation and Marketing Revenues [Member]
Reportable Segment Information
Revenue from Contracts with Customers		2,108.3		1,621.0		1,721.8
Generation and Marketing [Member] | Other Revenues [Member]
Reportable Segment Information
Total Revenues		209.1	[7],[8]	43.6	[9],[10]	59.9	[11],[12]
All Other [Member]
Reportable Segment Information
Sales to AEP Affiliates	[21]	55.9		88.6		81.1
Total Revenues	[21]	72.2		96.8		95.8
Asset Impairments and Other Related Charges	[21]	0.0				0.0
Utilities Operating Expense, Depreciation and Amortization	[21]	0.9		0.8		0.6
Interest Expense	[21]	180.8		196.4		193.7
Income Tax Expense (Benefit)	[21]	(61.6)		(5.0)		27.6
Equity Earnings (Loss) of Unconsolidated Subsidiaries	[21]	23.9		2.6		0.1
Net Income (Loss)	[21]	(64.2)		(89.6)		(141.0)
Gross Property Additions	[21]	25.5		16.0		14.5
Balance Sheet Information
Property, Plant and Equipment, Gross, Period Increase (Decrease)	[21]	418.4		407.3
Accumulated Depreciation and Amortization	[21]	188.3		184.1
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET	[21]	230.1		223.2
Total Assets	[21],[22]	5,846.5		5,987.1		5,440.0
Investments in Equity Method Investees	[21]	93.3		68.8		65.4
Affiliated Long Term Debt Current	[21]					0.0
Long-term Debt Due Within One Year	[21],[23]	308.9		410.4		501.8
Long-term Debt - Affiliated	[21]	0.0		0.0		0.0
Long-term Debt	[21],[23]	6,460.4		5,873.2		3,122.9
Total Long-term Debt Outstanding	[21]	6,769.3		6,283.6		3,624.7
All Other [Member] | Other Revenues [Member]
Reportable Segment Information
Revenue from Contracts with Customers	[21]	16.3		8.2		14.7
Total Revenues		10.7	[7],[8]	9.8	[9],[10]	(8.9)	[11],[12]
State Transcos [Member] | AEP Transmission Co [Member]
Reportable Segment Information
Sales to AEP Affiliates		1,153.9		896.3		806.7
Total Revenues		1,469.3		1,145.7		1,021.4
Utilities Operating Expense, Depreciation and Amortization		297.3		249.0		176.0
Interest Income		0.1		0.9		1.3
Allowance for Equity Funds Used During Construction		67.2		74.0		84.3
Interest Expense		141.2		127.8		97.4
Income Tax Expense (Benefit)		144.1		106.5		117.1
Net Income (Loss)		591.5		422.3		438.6
Gross Property Additions		1,442.7		1,621.9		1,419.5
Balance Sheet Information
Property, Plant and Equipment, Gross, Period Increase (Decrease)		12,708.5		11,345.6
Accumulated Depreciation and Amortization		772.8		572.8
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		11,935.7		10,772.8
Notes Receivable, Related Parties		0.0		0.0
Total Assets		12,564.3	[6]	11,185.1		9,865.0
Total Long-term Debt Outstanding		4,390.0		3,990.0		3,465.0
State Transcos [Member] | Transmission [Member] | AEP Transmission Co [Member]
Reportable Segment Information
Revenue from Contracts with Customers		315.1		248.8		214.6
State Transcos [Member] | Other Revenues [Member] | AEP Transmission Co [Member]
Reportable Segment Information
Revenue from Contracts with Customers		0.3		0.6		0.1
AEPTCo Parent [Member] | AEP Transmission Co [Member]
Reportable Segment Information
Sales to AEP Affiliates		0.0		0.0		0.0
Total Revenues		0.0		0.0		0.0
Utilities Operating Expense, Depreciation and Amortization		0.0		0.0		0.0
Interest Income		158.1		149.6		123.8
Allowance for Equity Funds Used During Construction		0.0		0.0		0.0
Interest Expense		157.7		148.1		122.1
Income Tax Expense (Benefit)		0.0		0.2		0.3
Net Income (Loss)	[24]	0.2		1.1		1.1
Gross Property Additions		0.0		0.0		0.0
Balance Sheet Information
Property, Plant and Equipment, Gross, Period Increase (Decrease)		0.0		0.0
Accumulated Depreciation and Amortization		0.0		0.0
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET		0.0		0.0
Notes Receivable, Related Parties		4,343.9		3,948.5
Total Assets	[25]	4,389.5	[6]	4,084.0		3,519.1
Total Long-term Debt Outstanding		4,343.9		3,948.5		3,427.3
AEPTCo Parent [Member] | Transmission [Member] | AEP Transmission Co [Member]
Reportable Segment Information
Revenue from Contracts with Customers		0.0		0.0		0.0
AEPTCo Parent [Member] | Other Revenues [Member] | AEP Transmission Co [Member]
Reportable Segment Information
Revenue from Contracts with Customers		$ 0.0		$ 0.0		$ 0.0

[1] Amount excludes $2.3 billion and $165 million for AEP and AEPTCo, respectively, of Property, Plant and Equipment - Net classified as Assets Held for Sale on the balance sheet. See “Disposition of KPCo and KTCo” section of Note 7 for additional information.

[2] Amount includes Assets Held for Sale on the balance sheet. See “Disposition of KPCo and KTCo” section of Note 7 for additional information.

[3] 2021 amount excludes $1.1 billion of Total Long-term Debt Outstanding classified as Liabilities Held for Sale on the balance sheet. See “Disposition of KPCo and KTCo” section of Note 7 for additional information.

[4] Amount excludes $1.1 billion of Total Long-term Debt Outstanding classified as Liabilities Held for Sale on the balance sheet. See “Disposition of KPCo and KTCo” section of Note 7 for additional information

[5] The 2021 book value amount excludes Long-term Debt of $1.1 billion classified as Liabilities Held for Sale on the balance sheets. See “Disposition of KPCo and KTCo” section of Note 7 for additional information.

[6] Amount includes Assets Held for Sale on the balance sheet. See “Disposition of KPCo and KTCo” section of Note 7 for additional information.

[7] Amounts include affiliated and nonaffiliated revenues.

[8] Generation & Marketing includes economic hedge activity.

[9] Amounts include affiliated and nonaffiliated revenues.

[10] Generation & Marketing includes economic hedge activity.

[11] Amounts include affiliated and nonaffiliated revenues.

[12] Generation & Marketing includes economic hedge activity.

[13] Amounts include affiliated and nonaffiliated revenues.

[14] Amounts include affiliated and nonaffiliated revenues.

[15] Amounts include affiliated and nonaffiliated revenues.

[16] Includes eliminations due to an intercompany finance lease.

[17] Reconciling Adjustments for Total Assets primarily include elimination of intercompany advances to affiliates and intercompany accounts receivable.

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

[19] Elimination of intercompany debt.

[20] Primarily relates to elimination of Notes Receivable from the State Transcos.

[21] Corporate and Other primarily includes the purchasing of receivables from certain AEP utility subsidiaries. This segment also includes Parent’s guarantee revenue received from affiliates, investment income, interest income, interest expense and other nonallocated costs.

[22] Includes elimination of AEP Parent’s investments in wholly-owned subsidiary companies.

[23] Amounts reflect the impact of fair value hedge accounting. See “Accounting for Fair Value Hedging Strategies” section of Note 10 for additional information.

[24] Includes elimination of AEPTCo Parent’s equity earnings in the State Transcos.

[25] Includes elimination of AEPTCo Parent’s investments in the State Transcos.