Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Current Assets
Cash and Cash Equivalents	$ 1,554.6	$ 246.8
Restricted Cash	116.2	185.8
Other Temporary Investments	185.2	202.7
Fuel	550.9	528.5
Other Inventory, Supplies, Gross	645.0	640.7
Property, Plant and Equipment
Other Property, Plant and Equipment	4,913.2	4,811.5
Accumulated Depreciation and Amortization	19,368.1	19,007.6
Other Noncurrent Assets
Securitized Transition Assets	789.1	858.1
Current Liabilities
Long-term Debt Due Within One Year	2,109.7	1,598.7
Accrued Interest	307.9	243.6
Noncurrent Liabilities
Long-term Debt	$ 25,783.0	$ 25,126.8
Equity
Common Stock, Par Value Per Share	$ 6.50	$ 6.50
Common Stock, Shares Authorized	600,000,000	600,000,000
Common Stock, Shares, Issued	515,411,847	514,373,631
Treasury Stock, Shares	20,204,160	20,204,160
AEP Subsidiaries [Member]
Current Assets
Restricted Cash	$ 116.2	$ 185.8
Other Temporary Investments	163.6	187.8
Current Liabilities
Long-term Debt Due Within One Year	289.6	565.1
Noncurrent Liabilities
Long-term Debt	1,037.6	907.0
AEP Texas Inc. [Member]
Current Assets
Cash and Cash Equivalents	0.1	3.1
Restricted Cash	100.1	154.7
Fuel	6.4	5.9
Other Inventory, Supplies, Gross	63.8	56.7
Property, Plant and Equipment
Other Property, Plant and Equipment	829.1	805.9
Accumulated Depreciation and Amortization	1,800.1	1,758.1
Other Noncurrent Assets
Securitized Transition Assets	560.5	623.4
Current Liabilities
Long-term Debt Due Within One Year	289.0	392.1
Accrued Interest	54.8	35.7
Noncurrent Liabilities
Long-term Debt	4,156.4	4,166.3
AEP Texas Inc. [Member] | AEP Texas Transition Funding and Restoration Funding [Member]
Current Assets
Restricted Cash	100.1	154.7
Other Noncurrent Assets
Securitized Transition Assets	560.7	621.2
Current Liabilities
Long-term Debt Due Within One Year	178.3	281.4
Accrued Interest	4.9	7.5
Noncurrent Liabilities
Long-term Debt	484.7	495.4
Appalachian Power Co [Member]
Current Assets
Cash and Cash Equivalents	2.8	3.3
Restricted Cash	15.7	23.5
Fuel	160.0	149.7
Other Inventory, Supplies, Gross	100.4	105.2
Property, Plant and Equipment
Other Property, Plant and Equipment	585.5	571.3
Accumulated Depreciation and Amortization	4,497.0	4,432.3
Other Noncurrent Assets
Securitized Transition Assets	228.5	234.7
Current Liabilities
Long-term Debt Due Within One Year	583.3	215.6
Accrued Interest	67.0	47.9
Noncurrent Liabilities
Long-term Debt	$ 3,769.1	$ 4,148.2
Equity
Common Stock, Shares Authorized	30,000,000	30,000,000
Common Stock, Shares Outstanding	13,499,500	13,499,500
Indiana Michigan Power Co [Member]
Current Assets
Cash and Cash Equivalents	$ 1.8	$ 2.0
Fuel	71.7	56.2
Other Inventory, Supplies, Gross	171.1	171.3
Property, Plant and Equipment
Other Property, Plant and Equipment	617.4	632.6
Accumulated Depreciation and Amortization	3,356.3	3,294.3
Current Liabilities
Long-term Debt Due Within One Year	133.6	139.7
Accrued Interest	20.3	36.2
Noncurrent Liabilities
Long-term Debt	$ 2,894.4	$ 2,910.5
Equity
Common Stock, No Par Value	$ 0	$ 0
Common Stock, Shares Authorized	2,500,000	2,500,000
Common Stock, Shares Outstanding	1,400,000	1,400,000
Indiana Michigan Power Co [Member] | DCC Fuel [Member]
Current Liabilities
Long-term Debt Due Within One Year	$ 80.0	$ 86.1
Ohio Power Co [Member]
Current Assets
Cash and Cash Equivalents	3.1	3.7
Other Inventory, Supplies, Gross	58.3	52.3
Property, Plant and Equipment
Other Property, Plant and Equipment	797.2	765.8
Accumulated Depreciation and Amortization	2,292.8	2,263.0
Current Liabilities
Long-term Debt Due Within One Year	0.1	0.1
Noncurrent Liabilities
Long-term Debt	$ 2,429.0	$ 2,081.9
Equity
Common Stock, No Par Value	$ 0	$ 0
Common Stock, Shares Authorized	40,000,000	40,000,000
Common Stock, Shares Outstanding	27,952,473	27,952,473
Public Service Co Of Oklahoma [Member]
Current Assets
Cash and Cash Equivalents	$ 1.1	$ 1.5
Fuel	19.6	12.2
Other Inventory, Supplies, Gross	47.9	46.8
Property, Plant and Equipment
Other Property, Plant and Equipment	350.3	342.1
Accumulated Depreciation and Amortization	1,615.8	1,580.1
Current Liabilities
Long-term Debt Due Within One Year	263.2	13.2
Noncurrent Liabilities
Long-term Debt	$ 1,123.1	$ 1,373.0
Equity
Common Stock, Par Value Per Share	$ 15	$ 15
Common Stock, Shares Authorized	11,000,000	11,000,000
Common Stock, Shares, Issued	10,482,000	10,482,000
Common Stock, Shares Outstanding	9,013,000	9,013,000
Southwestern Electric Power Co [Member]
Current Assets
Cash and Cash Equivalents	$ 1.4	$ 1.6
Fuel	147.9	140.1
Other Inventory, Supplies, Gross	93.8	94.0
Property, Plant and Equipment
Other Property, Plant and Equipment	767.2	733.4
Accumulated Depreciation and Amortization	2,918.7	2,873.7
Current Liabilities
Long-term Debt Due Within One Year	121.2	121.2
Accrued Interest	21.9	34.6
Noncurrent Liabilities
Long-term Debt	$ 2,533.2	$ 2,534.4
Equity
Common Stock, Par Value Per Share	$ 18	$ 18
Common Stock, Shares Authorized	7,600,000	7,600,000
Common Stock, Shares Outstanding	7,536,640	7,536,640
Southwestern Electric Power Co [Member] | Sabine Mining Co [Member]
Current Assets
Fuel	$ 42.0	$ 47.0
Other Inventory, Supplies, Gross	23.3	23.1
Property, Plant and Equipment
Other Property, Plant and Equipment	213.5	212.3
Accumulated Depreciation and Amortization	$ 112.0	$ 107.5