Fair Value Long-term Debt, Other Temporary Investments, Nuclear Trusts (Details) - USD ($) $ in Millions |
12 Months Ended |
Dec. 31, 2021 |
Dec. 31, 2020 |
Dec. 31, 2019 |
Book Values and Fair Values of Long - term Debt |
|
|
|
|
|
Total Long-term Debt Outstanding |
|
$ 33,454.5
|
[1],[2],[3] |
$ 31,072.5
|
$ 26,725.5
|
Long-term Debt, Fair Value |
[5] |
37,564.7
|
[4] |
37,457.0
|
|
Other Temporary Investments |
|
|
|
|
|
Cost |
|
232.0
|
|
214.9
|
|
Gross Unrealized Gains |
|
36.4
|
|
31.5
|
|
Gross Unrealized Losses |
|
0.0
|
|
0.0
|
|
Fair Value |
|
268.4
|
|
246.4
|
|
Debt and Equity Securities Within Other Temporary Investments |
|
|
|
|
|
Proceeds From Investment Sales |
|
15.0
|
|
50.9
|
21.2
|
Purchases of Investments |
|
26.9
|
|
41.6
|
45.0
|
Gross Realized Gains on Investment Sales |
|
3.6
|
|
3.8
|
0.0
|
Gross Realized Losses on Investment Sales |
|
0.0
|
|
0.2
|
0.4
|
Nuclear Trust Fund Investments |
|
|
|
|
|
Fair Value |
|
3,867.0
|
|
3,306.7
|
|
Contractual Maturities, Fair Value of Debt Securities |
|
|
|
|
|
Fair Value |
|
3,867.0
|
|
3,306.7
|
|
Fair Value Measurements (Textuals) |
|
|
|
|
|
Liabilities Held for Sale |
|
1,880.9
|
|
0.0
|
|
Spent Nuclear Fuel and Decommissioning Trusts [Member] |
|
|
|
|
|
Nuclear Trust Fund Investments |
|
|
|
|
|
Gross Unrealized Gains |
|
1,974.7
|
|
1,509.8
|
|
Other-Than-Temporary Impairments |
|
(10.1)
|
|
(9.2)
|
|
Securities Activity Within the Decommissioning and SNF Trusts |
|
|
|
|
|
Proceeds from Investment Sales |
|
1,886.4
|
|
1,593.4
|
1,473.0
|
Purchases of Investments |
|
1,928.2
|
|
1,637.2
|
1,531.0
|
Gross Realized Gains on Investment Sales |
|
103.2
|
|
26.4
|
76.5
|
Gross Realized Losses on Investment Sales |
|
16.5
|
|
26.1
|
24.3
|
Contractual Maturities, Fair Value of Debt Securities |
|
|
|
|
|
Within 1 year |
|
302.4
|
|
|
|
After 1 year through 5 years |
|
431.2
|
|
|
|
After 5 years through 10 years |
|
227.7
|
|
|
|
After 10 years |
|
279.1
|
|
|
|
Fair Value Measurements (Textuals) |
|
|
|
|
|
Adjusted Cost of Debt Securities |
|
1,200.0
|
|
1,100.0
|
|
Adjusted Cost of Domestic Equity Securities |
|
641.0
|
|
654.0
|
|
AEP Texas Inc. [Member] |
|
|
|
|
|
Book Values and Fair Values of Long - term Debt |
|
|
|
|
|
Total Long-term Debt Outstanding |
|
5,180.8
|
|
4,820.4
|
|
Long-term Debt, Fair Value |
|
5,663.8
|
|
5,682.6
|
|
AEP Transmission Co [Member] |
|
|
|
|
|
Book Values and Fair Values of Long - term Debt |
|
|
|
|
|
Total Long-term Debt Outstanding |
|
4,343.9
|
|
3,948.5
|
3,427.3
|
Long-term Debt, Fair Value |
|
4,968.2
|
|
4,984.3
|
|
Fair Value Measurements (Textuals) |
|
|
|
|
|
Liabilities Held for Sale |
|
27.6
|
|
0.0
|
|
Appalachian Power Co [Member] |
|
|
|
|
|
Book Values and Fair Values of Long - term Debt |
|
|
|
|
|
Total Long-term Debt Outstanding |
|
4,938.9
|
|
4,834.1
|
|
Long-term Debt, Fair Value |
|
6,037.1
|
|
6,391.8
|
|
Indiana Michigan Power Co [Member] |
|
|
|
|
|
Book Values and Fair Values of Long - term Debt |
|
|
|
|
|
Total Long-term Debt Outstanding |
|
3,195.0
|
|
3,029.9
|
|
Long-term Debt, Fair Value |
|
3,748.0
|
|
3,775.3
|
|
Nuclear Trust Fund Investments |
|
|
|
|
|
Fair Value |
|
3,867.0
|
|
3,306.7
|
|
Contractual Maturities, Fair Value of Debt Securities |
|
|
|
|
|
Fair Value |
|
3,867.0
|
|
3,306.7
|
|
Indiana Michigan Power Co [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member] |
|
|
|
|
|
Nuclear Trust Fund Investments |
|
|
|
|
|
Gross Unrealized Gains |
|
1,974.7
|
|
1,509.8
|
|
Other-Than-Temporary Impairments |
|
(10.1)
|
|
(9.2)
|
|
Securities Activity Within the Decommissioning and SNF Trusts |
|
|
|
|
|
Proceeds from Investment Sales |
|
1,886.4
|
|
1,593.4
|
1,473.0
|
Purchases of Investments |
|
1,928.2
|
|
1,637.2
|
1,531.0
|
Gross Realized Gains on Investment Sales |
|
103.2
|
|
26.4
|
76.5
|
Gross Realized Losses on Investment Sales |
|
16.5
|
|
26.1
|
$ 24.3
|
Contractual Maturities, Fair Value of Debt Securities |
|
|
|
|
|
Within 1 year |
|
302.4
|
|
|
|
After 1 year through 5 years |
|
431.2
|
|
|
|
After 5 years through 10 years |
|
227.7
|
|
|
|
After 10 years |
|
279.1
|
|
|
|
Fair Value Measurements (Textuals) |
|
|
|
|
|
Adjusted Cost of Debt Securities |
|
1,200.0
|
|
1,100.0
|
|
Adjusted Cost of Domestic Equity Securities |
|
641.0
|
|
654.0
|
|
Ohio Power Co [Member] |
|
|
|
|
|
Book Values and Fair Values of Long - term Debt |
|
|
|
|
|
Total Long-term Debt Outstanding |
|
2,968.5
|
|
2,430.2
|
|
Long-term Debt, Fair Value |
|
3,437.5
|
|
3,154.9
|
|
Public Service Co Of Oklahoma [Member] |
|
|
|
|
|
Book Values and Fair Values of Long - term Debt |
|
|
|
|
|
Total Long-term Debt Outstanding |
|
1,913.5
|
|
1,373.8
|
|
Long-term Debt, Fair Value |
|
2,163.7
|
|
1,732.1
|
|
Southwestern Electric Power Co [Member] |
|
|
|
|
|
Book Values and Fair Values of Long - term Debt |
|
|
|
|
|
Total Long-term Debt Outstanding |
|
3,395.2
|
|
2,636.4
|
|
Long-term Debt, Fair Value |
|
3,792.9
|
|
3,210.1
|
|
Cash [Member] |
|
|
|
|
|
Other Temporary Investments |
|
|
|
|
|
Cost |
[6] |
48.0
|
|
45.6
|
|
Gross Unrealized Gains |
[6] |
0.0
|
|
0.0
|
|
Gross Unrealized Losses |
[6] |
0.0
|
|
0.0
|
|
Fair Value |
[6] |
48.0
|
|
45.6
|
|
Other Cash Deposits [Member] |
|
|
|
|
|
Other Temporary Investments |
|
|
|
|
|
Cost |
|
10.0
|
|
22.7
|
|
Gross Unrealized Gains |
|
0.0
|
|
0.0
|
|
Gross Unrealized Losses |
|
0.0
|
|
0.0
|
|
Fair Value |
[7] |
10.0
|
|
22.7
|
|
Mutual Funds Fixed Income [Member] |
|
|
|
|
|
Other Temporary Investments |
|
|
|
|
|
Cost |
[8] |
154.3
|
|
120.7
|
|
Gross Unrealized Gains |
[8] |
0.5
|
|
2.8
|
|
Gross Unrealized Losses |
[8] |
0.0
|
|
0.0
|
|
Fair Value |
[8] |
154.8
|
|
123.5
|
|
Mutual Funds Equity [Member] |
|
|
|
|
|
Other Temporary Investments |
|
|
|
|
|
Cost |
|
19.7
|
|
25.9
|
|
Gross Unrealized Gains |
|
35.9
|
|
28.7
|
|
Gross Unrealized Losses |
|
0.0
|
|
0.0
|
|
Fair Value |
|
55.6
|
|
54.6
|
|
Fixed Income Funds [Member] |
|
|
|
|
|
Nuclear Trust Fund Investments |
|
|
|
|
|
Fair Value |
|
1,240.4
|
|
1,226.2
|
|
Contractual Maturities, Fair Value of Debt Securities |
|
|
|
|
|
Fair Value |
|
1,240.4
|
|
1,226.2
|
|
Fixed Income Funds [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member] |
|
|
|
|
|
Nuclear Trust Fund Investments |
|
|
|
|
|
Gross Unrealized Gains |
|
73.4
|
|
109.0
|
|
Other-Than-Temporary Impairments |
|
(10.1)
|
|
(9.2)
|
|
Fixed Income Funds [Member] | Indiana Michigan Power Co [Member] |
|
|
|
|
|
Nuclear Trust Fund Investments |
|
|
|
|
|
Fair Value |
|
1,240.4
|
|
1,226.2
|
|
Contractual Maturities, Fair Value of Debt Securities |
|
|
|
|
|
Fair Value |
|
1,240.4
|
|
1,226.2
|
|
Fixed Income Funds [Member] | Indiana Michigan Power Co [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member] |
|
|
|
|
|
Nuclear Trust Fund Investments |
|
|
|
|
|
Gross Unrealized Gains |
|
73.4
|
|
109.0
|
|
Other-Than-Temporary Impairments |
|
(10.1)
|
|
(9.2)
|
|
Domestic [Member] |
|
|
|
|
|
Nuclear Trust Fund Investments |
|
|
|
|
|
Fair Value |
[9] |
2,541.9
|
|
2,054.7
|
|
Contractual Maturities, Fair Value of Debt Securities |
|
|
|
|
|
Fair Value |
[9] |
2,541.9
|
|
2,054.7
|
|
Domestic [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member] |
|
|
|
|
|
Unrealized Gain on Securities |
|
1,900.0
|
|
1,400.0
|
|
Unrealized Loss on Securities |
|
4.0
|
|
9.0
|
|
Nuclear Trust Fund Investments |
|
|
|
|
|
Gross Unrealized Gains |
[10] |
1,901.3
|
|
1,400.8
|
|
Other-Than-Temporary Impairments |
|
0.0
|
|
0.0
|
|
Domestic [Member] | Indiana Michigan Power Co [Member] |
|
|
|
|
|
Nuclear Trust Fund Investments |
|
|
|
|
|
Fair Value |
[9] |
2,541.9
|
|
2,054.7
|
|
Contractual Maturities, Fair Value of Debt Securities |
|
|
|
|
|
Fair Value |
[9] |
2,541.9
|
|
2,054.7
|
|
Domestic [Member] | Indiana Michigan Power Co [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member] |
|
|
|
|
|
Unrealized Gain on Securities |
|
1,900.0
|
|
1,400.0
|
|
Unrealized Loss on Securities |
|
4.0
|
|
9.0
|
|
Nuclear Trust Fund Investments |
|
|
|
|
|
Gross Unrealized Gains |
[10] |
1,901.3
|
|
1,400.8
|
|
Other-Than-Temporary Impairments |
|
0.0
|
|
0.0
|
|
Cash and Cash Equivalents [Member] |
|
|
|
|
|
Nuclear Trust Fund Investments |
|
|
|
|
|
Fair Value |
[11] |
84.7
|
|
25.8
|
|
Contractual Maturities, Fair Value of Debt Securities |
|
|
|
|
|
Fair Value |
[11] |
84.7
|
|
25.8
|
|
Cash and Cash Equivalents [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member] |
|
|
|
|
|
Nuclear Trust Fund Investments |
|
|
|
|
|
Gross Unrealized Gains |
|
0.0
|
|
0.0
|
|
Other-Than-Temporary Impairments |
|
0.0
|
|
0.0
|
|
Cash and Cash Equivalents [Member] | Indiana Michigan Power Co [Member] |
|
|
|
|
|
Nuclear Trust Fund Investments |
|
|
|
|
|
Fair Value |
[11] |
84.7
|
|
25.8
|
|
Contractual Maturities, Fair Value of Debt Securities |
|
|
|
|
|
Fair Value |
[11] |
84.7
|
|
25.8
|
|
Cash and Cash Equivalents [Member] | Indiana Michigan Power Co [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member] |
|
|
|
|
|
Nuclear Trust Fund Investments |
|
|
|
|
|
Gross Unrealized Gains |
|
0.0
|
|
0.0
|
|
Other-Than-Temporary Impairments |
|
0.0
|
|
0.0
|
|
US Government Agencies Debt Securities [Member] |
|
|
|
|
|
Nuclear Trust Fund Investments |
|
|
|
|
|
Fair Value |
|
1,156.4
|
|
1,025.6
|
|
Contractual Maturities, Fair Value of Debt Securities |
|
|
|
|
|
Fair Value |
|
1,156.4
|
|
1,025.6
|
|
US Government Agencies Debt Securities [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member] |
|
|
|
|
|
Nuclear Trust Fund Investments |
|
|
|
|
|
Gross Unrealized Gains |
|
66.3
|
|
98.5
|
|
Other-Than-Temporary Impairments |
|
(7.9)
|
|
(7.1)
|
|
US Government Agencies Debt Securities [Member] | Indiana Michigan Power Co [Member] |
|
|
|
|
|
Nuclear Trust Fund Investments |
|
|
|
|
|
Fair Value |
|
1,156.4
|
|
1,025.6
|
|
Contractual Maturities, Fair Value of Debt Securities |
|
|
|
|
|
Fair Value |
|
1,156.4
|
|
1,025.6
|
|
US Government Agencies Debt Securities [Member] | Indiana Michigan Power Co [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member] |
|
|
|
|
|
Nuclear Trust Fund Investments |
|
|
|
|
|
Gross Unrealized Gains |
|
66.3
|
|
98.5
|
|
Other-Than-Temporary Impairments |
|
(7.9)
|
|
(7.1)
|
|
Corporate Debt [Member] |
|
|
|
|
|
Nuclear Trust Fund Investments |
|
|
|
|
|
Fair Value |
|
76.7
|
|
86.3
|
|
Contractual Maturities, Fair Value of Debt Securities |
|
|
|
|
|
Fair Value |
|
76.7
|
|
86.3
|
|
Corporate Debt [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member] |
|
|
|
|
|
Nuclear Trust Fund Investments |
|
|
|
|
|
Gross Unrealized Gains |
|
6.7
|
|
9.6
|
|
Other-Than-Temporary Impairments |
|
(2.1)
|
|
(1.7)
|
|
Corporate Debt [Member] | Indiana Michigan Power Co [Member] |
|
|
|
|
|
Nuclear Trust Fund Investments |
|
|
|
|
|
Fair Value |
|
76.7
|
|
86.3
|
|
Contractual Maturities, Fair Value of Debt Securities |
|
|
|
|
|
Fair Value |
|
76.7
|
|
86.3
|
|
Corporate Debt [Member] | Indiana Michigan Power Co [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member] |
|
|
|
|
|
Nuclear Trust Fund Investments |
|
|
|
|
|
Gross Unrealized Gains |
|
6.7
|
|
9.6
|
|
Other-Than-Temporary Impairments |
|
(2.1)
|
|
(1.7)
|
|
State and Local Jurisdiction |
|
|
|
|
|
Nuclear Trust Fund Investments |
|
|
|
|
|
Fair Value |
|
7.3
|
|
114.3
|
|
Contractual Maturities, Fair Value of Debt Securities |
|
|
|
|
|
Fair Value |
|
7.3
|
|
114.3
|
|
State and Local Jurisdiction | Spent Nuclear Fuel and Decommissioning Trusts [Member] |
|
|
|
|
|
Nuclear Trust Fund Investments |
|
|
|
|
|
Gross Unrealized Gains |
|
0.4
|
|
0.9
|
|
Other-Than-Temporary Impairments |
|
(0.1)
|
|
(0.4)
|
|
State and Local Jurisdiction | Indiana Michigan Power Co [Member] |
|
|
|
|
|
Nuclear Trust Fund Investments |
|
|
|
|
|
Fair Value |
|
7.3
|
|
114.3
|
|
Contractual Maturities, Fair Value of Debt Securities |
|
|
|
|
|
Fair Value |
|
7.3
|
|
114.3
|
|
State and Local Jurisdiction | Indiana Michigan Power Co [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member] |
|
|
|
|
|
Nuclear Trust Fund Investments |
|
|
|
|
|
Gross Unrealized Gains |
|
0.4
|
|
0.9
|
|
Other-Than-Temporary Impairments |
|
(0.1)
|
|
(0.4)
|
|
Equity units [Member] |
|
|
|
|
|
Book Values and Fair Values of Long - term Debt |
|
|
|
|
|
Long-term Debt, Fair Value |
|
1,700.0
|
|
$ 1,700.0
|
|
Held For Sale [Member] |
|
|
|
|
|
Fair Value Measurements (Textuals) |
|
|
|
|
|
Liabilities Held for Sale |
|
1,100.0
|
|
|
|
Fair Value Held for Sale [Member] |
|
|
|
|
|
Fair Value Measurements (Textuals) |
|
|
|
|
|
Liabilities Held for Sale |
|
$ 1,200.0
|
|
|
|
|
|