Fair Value Long-term Debt, Other Temporary Investments, Nuclear Trusts (Details) - USD ($)
$ in Millions |
12 Months Ended |
Dec. 31, 2023 |
Dec. 31, 2022 |
Dec. 31, 2021 |
| Book Values and Fair Values of Long - term Debt |
|
|
|
|
| Total Long-term Debt Outstanding |
|
$ 40,143.2
|
$ 36,801.0
|
|
| Long-term Debt, Fair Value |
[1] |
37,325.7
|
35,915.9
|
|
| Other Temporary Investments |
|
|
|
|
| Cost |
|
243.5
|
223.6
|
|
| Gross Unrealized Gains |
|
25.9
|
19.4
|
|
| Gross Unrealized Losses |
|
(6.2)
|
(8.3)
|
|
| Fair Value |
|
263.2
|
234.7
|
|
| Debt and Equity Securities Within Other Temporary Investments |
|
|
|
|
| Proceeds From Investment Sales |
|
7.6
|
30.2
|
$ 15.0
|
| Purchases of Investments |
|
18.5
|
18.8
|
26.9
|
| Gross Realized Gains on Investment Sales |
|
1.1
|
6.1
|
3.6
|
| Gross Realized Losses on Investment Sales |
|
0.3
|
1.3
|
0.0
|
| Nuclear Trust Fund Investments |
|
|
|
|
| Fair Value |
|
3,860.2
|
3,341.2
|
|
| Securities Activity Within the Decommissioning and SNF Trusts |
|
|
|
|
| Payments to Acquire Investments |
|
2,863.6
|
2,784.2
|
1,955.1
|
| Contractual Maturities, Fair Value of Debt Securities |
|
|
|
|
| Fair Value |
|
3,860.2
|
3,341.2
|
|
| Spent Nuclear Fuel and Decommissioning Trusts [Member] |
|
|
|
|
| Securities Activity Within the Decommissioning and SNF Trusts |
|
|
|
|
| Payments to Acquire Investments |
|
2,845.1
|
2,765.4
|
1,928.2
|
| Realized Investment Gains (Losses) |
|
99.0
|
52.4
|
103.2
|
| Gain (Loss) on Investments |
|
26.6
|
42.6
|
16.5
|
| Contractual Maturities, Fair Value of Debt Securities |
|
|
|
|
| Within 1 year |
|
359.6
|
|
|
| After 1 year through 5 years |
|
597.6
|
|
|
| After 5 years through 10 years |
|
180.7
|
|
|
| After 10 years |
|
268.9
|
|
|
| Fair Value Measurements (Textuals) |
|
|
|
|
| Adjusted Cost of Debt Securities |
|
1,400.0
|
1,200.0
|
|
| Adjusted Cost of Domestic Equity Securities |
|
568.0
|
654.0
|
|
| Proceeds from Sale of Other Investments |
|
2,787.5
|
2,713.6
|
1,886.4
|
| Realized Investment Gains (Losses) |
|
99.0
|
52.4
|
103.2
|
| Gain (Loss) on Investments |
|
26.6
|
42.6
|
16.5
|
| Other than Temporary Impairment Losses, Investments |
|
(41.8)
|
(28.5)
|
|
| Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax |
|
1,902.9
|
1,496.3
|
|
| Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax |
|
(10.0)
|
(29.0)
|
|
| Cash [Member] |
|
|
|
|
| Other Temporary Investments |
|
|
|
|
| Cost |
[2] |
48.9
|
47.1
|
|
| Gross Unrealized Gains |
[2] |
0.0
|
0.0
|
|
| Gross Unrealized Losses |
[2] |
0.0
|
0.0
|
|
| Fair Value |
[2] |
48.9
|
47.1
|
|
| Other Cash Deposits [Member] |
|
|
|
|
| Other Temporary Investments |
|
|
|
|
| Cost |
|
13.9
|
9.0
|
|
| Gross Unrealized Gains |
|
0.0
|
0.0
|
|
| Gross Unrealized Losses |
|
0.0
|
0.0
|
|
| Fair Value |
|
13.9
|
9.0
|
|
| Mutual Funds Fixed Income [Member] |
|
|
|
|
| Other Temporary Investments |
|
|
|
|
| Cost |
[3] |
165.9
|
152.4
|
|
| Gross Unrealized Gains |
[3] |
0.0
|
0.0
|
|
| Gross Unrealized Losses |
[3] |
(6.2)
|
(8.3)
|
|
| Fair Value |
[3] |
159.7
|
144.1
|
|
| Mutual Funds Equity [Member] |
|
|
|
|
| Other Temporary Investments |
|
|
|
|
| Cost |
|
14.8
|
15.1
|
|
| Gross Unrealized Gains |
|
25.9
|
19.4
|
|
| Gross Unrealized Losses |
|
0.0
|
0.0
|
|
| Fair Value |
|
40.7
|
34.5
|
|
| Domestic [Member] |
|
|
|
|
| Nuclear Trust Fund Investments |
|
|
|
|
| Fair Value |
[4] |
2,436.6
|
2,131.3
|
|
| Contractual Maturities, Fair Value of Debt Securities |
|
|
|
|
| Fair Value |
[4] |
2,436.6
|
2,131.3
|
|
| Domestic [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member] |
|
|
|
|
| Fair Value Measurements (Textuals) |
|
|
|
|
| Other than Temporary Impairment Losses, Investments |
|
0.0
|
0.0
|
|
| Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax |
|
1,869.5
|
1,483.7
|
|
| Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax |
|
(0.9)
|
(6.4)
|
|
| Fixed Income Funds [Member] |
|
|
|
|
| Nuclear Trust Fund Investments |
|
|
|
|
| Fair Value |
|
1,406.8
|
1,188.7
|
|
| Contractual Maturities, Fair Value of Debt Securities |
|
|
|
|
| Fair Value |
|
1,406.8
|
1,188.7
|
|
| Fixed Income Funds [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member] |
|
|
|
|
| Fair Value Measurements (Textuals) |
|
|
|
|
| Other than Temporary Impairment Losses, Investments |
|
(41.8)
|
(28.5)
|
|
| Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax |
|
33.4
|
12.6
|
|
| Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax |
|
(9.1)
|
(22.6)
|
|
| Cash and Cash Equivalents [Member] |
|
|
|
|
| Nuclear Trust Fund Investments |
|
|
|
|
| Fair Value |
[5] |
16.8
|
21.2
|
|
| Contractual Maturities, Fair Value of Debt Securities |
|
|
|
|
| Fair Value |
[5] |
16.8
|
21.2
|
|
| Cash and Cash Equivalents [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member] |
|
|
|
|
| Fair Value Measurements (Textuals) |
|
|
|
|
| Other than Temporary Impairment Losses, Investments |
|
0.0
|
0.0
|
|
| Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax |
|
0.0
|
0.0
|
|
| Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax |
|
0.0
|
0.0
|
|
| US Government Agencies Debt Securities [Member] |
|
|
|
|
| Nuclear Trust Fund Investments |
|
|
|
|
| Fair Value |
|
1,273.0
|
1,123.8
|
|
| Contractual Maturities, Fair Value of Debt Securities |
|
|
|
|
| Fair Value |
|
1,273.0
|
1,123.8
|
|
| US Government Agencies Debt Securities [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member] |
|
|
|
|
| Fair Value Measurements (Textuals) |
|
|
|
|
| Other than Temporary Impairment Losses, Investments |
|
(33.2)
|
(18.8)
|
|
| Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax |
|
28.6
|
11.8
|
|
| Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax |
|
(3.9)
|
(14.9)
|
|
| Corporate Debt [Member] |
|
|
|
|
| Nuclear Trust Fund Investments |
|
|
|
|
| Fair Value |
|
132.1
|
61.6
|
|
| Contractual Maturities, Fair Value of Debt Securities |
|
|
|
|
| Fair Value |
|
132.1
|
61.6
|
|
| Corporate Debt [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member] |
|
|
|
|
| Fair Value Measurements (Textuals) |
|
|
|
|
| Other than Temporary Impairment Losses, Investments |
|
(8.6)
|
(9.6)
|
|
| Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax |
|
4.8
|
0.7
|
|
| Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax |
|
(5.2)
|
(7.7)
|
|
| State and Local Jurisdiction |
|
|
|
|
| Nuclear Trust Fund Investments |
|
|
|
|
| Fair Value |
|
1.7
|
3.3
|
|
| Contractual Maturities, Fair Value of Debt Securities |
|
|
|
|
| Fair Value |
|
1.7
|
3.3
|
|
| State and Local Jurisdiction | Spent Nuclear Fuel and Decommissioning Trusts [Member] |
|
|
|
|
| Fair Value Measurements (Textuals) |
|
|
|
|
| Other than Temporary Impairment Losses, Investments |
|
0.0
|
(0.1)
|
|
| Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax |
|
0.0
|
0.1
|
|
| Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax |
|
0.0
|
0.0
|
|
| AEP Texas Inc. [Member] |
|
|
|
|
| Book Values and Fair Values of Long - term Debt |
|
|
|
|
| Total Long-term Debt Outstanding |
|
5,889.8
|
5,657.8
|
|
| Long-term Debt, Fair Value |
|
5,400.7
|
5,045.8
|
|
| AEP Transmission Co [Member] |
|
|
|
|
| Book Values and Fair Values of Long - term Debt |
|
|
|
|
| Total Long-term Debt Outstanding |
|
5,414.4
|
4,782.8
|
|
| Long-term Debt, Fair Value |
|
4,796.9
|
3,940.5
|
|
| Appalachian Power Co [Member] |
|
|
|
|
| Book Values and Fair Values of Long - term Debt |
|
|
|
|
| Total Long-term Debt Outstanding |
|
5,588.3
|
5,410.5
|
|
| Long-term Debt, Fair Value |
|
5,390.1
|
5,079.2
|
|
| Indiana Michigan Power Co [Member] |
|
|
|
|
| Book Values and Fair Values of Long - term Debt |
|
|
|
|
| Total Long-term Debt Outstanding |
|
3,499.4
|
3,260.8
|
|
| Long-term Debt, Fair Value |
|
3,291.6
|
2,929.0
|
|
| Nuclear Trust Fund Investments |
|
|
|
|
| Fair Value |
|
3,860.2
|
3,341.2
|
|
| Securities Activity Within the Decommissioning and SNF Trusts |
|
|
|
|
| Payments to Acquire Investments |
|
2,845.1
|
2,765.4
|
1,928.2
|
| Contractual Maturities, Fair Value of Debt Securities |
|
|
|
|
| Fair Value |
|
3,860.2
|
3,341.2
|
|
| Indiana Michigan Power Co [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member] |
|
|
|
|
| Securities Activity Within the Decommissioning and SNF Trusts |
|
|
|
|
| Payments to Acquire Investments |
|
2,845.1
|
2,765.4
|
1,928.2
|
| Realized Investment Gains (Losses) |
|
99.0
|
52.4
|
103.2
|
| Gain (Loss) on Investments |
|
26.6
|
42.6
|
16.5
|
| Contractual Maturities, Fair Value of Debt Securities |
|
|
|
|
| Within 1 year |
|
359.6
|
|
|
| After 1 year through 5 years |
|
597.6
|
|
|
| After 5 years through 10 years |
|
180.7
|
|
|
| After 10 years |
|
268.9
|
|
|
| Fair Value Measurements (Textuals) |
|
|
|
|
| Adjusted Cost of Debt Securities |
|
1,400.0
|
1,200.0
|
|
| Adjusted Cost of Domestic Equity Securities |
|
568.0
|
654.0
|
|
| Proceeds from Sale of Other Investments |
|
2,787.5
|
2,713.6
|
1,886.4
|
| Realized Investment Gains (Losses) |
|
99.0
|
52.4
|
103.2
|
| Gain (Loss) on Investments |
|
26.6
|
42.6
|
$ 16.5
|
| Other than Temporary Impairment Losses, Investments |
|
(41.8)
|
(28.5)
|
|
| Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax |
|
1,902.9
|
1,496.3
|
|
| Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax |
|
(10.0)
|
(29.0)
|
|
| Indiana Michigan Power Co [Member] | Domestic [Member] |
|
|
|
|
| Nuclear Trust Fund Investments |
|
|
|
|
| Fair Value |
[4] |
2,436.6
|
2,131.3
|
|
| Contractual Maturities, Fair Value of Debt Securities |
|
|
|
|
| Fair Value |
[4] |
2,436.6
|
2,131.3
|
|
| Indiana Michigan Power Co [Member] | Domestic [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member] |
|
|
|
|
| Fair Value Measurements (Textuals) |
|
|
|
|
| Other than Temporary Impairment Losses, Investments |
|
0.0
|
0.0
|
|
| Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax |
|
1,869.5
|
1,483.7
|
|
| Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax |
|
(0.9)
|
(6.4)
|
|
| Indiana Michigan Power Co [Member] | Fixed Income Funds [Member] |
|
|
|
|
| Nuclear Trust Fund Investments |
|
|
|
|
| Fair Value |
|
1,406.8
|
1,188.7
|
|
| Contractual Maturities, Fair Value of Debt Securities |
|
|
|
|
| Fair Value |
|
1,406.8
|
1,188.7
|
|
| Indiana Michigan Power Co [Member] | Fixed Income Funds [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member] |
|
|
|
|
| Fair Value Measurements (Textuals) |
|
|
|
|
| Other than Temporary Impairment Losses, Investments |
|
(41.8)
|
(28.5)
|
|
| Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax |
|
33.4
|
12.6
|
|
| Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax |
|
(9.1)
|
(22.6)
|
|
| Indiana Michigan Power Co [Member] | Cash and Cash Equivalents [Member] |
|
|
|
|
| Nuclear Trust Fund Investments |
|
|
|
|
| Fair Value |
[5] |
16.8
|
21.2
|
|
| Contractual Maturities, Fair Value of Debt Securities |
|
|
|
|
| Fair Value |
[5] |
16.8
|
21.2
|
|
| Indiana Michigan Power Co [Member] | Cash and Cash Equivalents [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member] |
|
|
|
|
| Fair Value Measurements (Textuals) |
|
|
|
|
| Other than Temporary Impairment Losses, Investments |
|
0.0
|
0.0
|
|
| Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax |
|
0.0
|
0.0
|
|
| Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax |
|
0.0
|
0.0
|
|
| Indiana Michigan Power Co [Member] | US Government Agencies Debt Securities [Member] |
|
|
|
|
| Nuclear Trust Fund Investments |
|
|
|
|
| Fair Value |
|
1,273.0
|
1,123.8
|
|
| Contractual Maturities, Fair Value of Debt Securities |
|
|
|
|
| Fair Value |
|
1,273.0
|
1,123.8
|
|
| Indiana Michigan Power Co [Member] | US Government Agencies Debt Securities [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member] |
|
|
|
|
| Fair Value Measurements (Textuals) |
|
|
|
|
| Other than Temporary Impairment Losses, Investments |
|
(33.2)
|
(18.8)
|
|
| Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax |
|
28.6
|
11.8
|
|
| Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax |
|
(3.9)
|
(14.9)
|
|
| Indiana Michigan Power Co [Member] | Corporate Debt [Member] |
|
|
|
|
| Nuclear Trust Fund Investments |
|
|
|
|
| Fair Value |
|
132.1
|
61.6
|
|
| Contractual Maturities, Fair Value of Debt Securities |
|
|
|
|
| Fair Value |
|
132.1
|
61.6
|
|
| Indiana Michigan Power Co [Member] | Corporate Debt [Member] | Spent Nuclear Fuel and Decommissioning Trusts [Member] |
|
|
|
|
| Fair Value Measurements (Textuals) |
|
|
|
|
| Other than Temporary Impairment Losses, Investments |
|
(8.6)
|
(9.6)
|
|
| Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax |
|
4.8
|
0.7
|
|
| Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax |
|
(5.2)
|
(7.7)
|
|
| Indiana Michigan Power Co [Member] | State and Local Jurisdiction |
|
|
|
|
| Nuclear Trust Fund Investments |
|
|
|
|
| Fair Value |
|
1.7
|
3.3
|
|
| Contractual Maturities, Fair Value of Debt Securities |
|
|
|
|
| Fair Value |
|
1.7
|
3.3
|
|
| Indiana Michigan Power Co [Member] | State and Local Jurisdiction | Spent Nuclear Fuel and Decommissioning Trusts [Member] |
|
|
|
|
| Fair Value Measurements (Textuals) |
|
|
|
|
| Other than Temporary Impairment Losses, Investments |
|
0.0
|
(0.1)
|
|
| Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax |
|
0.0
|
0.1
|
|
| Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax |
|
0.0
|
0.0
|
|
| Ohio Power Co [Member] |
|
|
|
|
| Book Values and Fair Values of Long - term Debt |
|
|
|
|
| Total Long-term Debt Outstanding |
|
3,366.8
|
2,970.3
|
|
| Long-term Debt, Fair Value |
|
2,992.1
|
2,516.6
|
|
| Public Service Co Of Oklahoma [Member] |
|
|
|
|
| Book Values and Fair Values of Long - term Debt |
|
|
|
|
| Total Long-term Debt Outstanding |
|
2,384.6
|
1,912.8
|
|
| Long-term Debt, Fair Value |
|
2,154.3
|
1,635.8
|
|
| Southwestern Electric Power Co [Member] |
|
|
|
|
| Book Values and Fair Values of Long - term Debt |
|
|
|
|
| Total Long-term Debt Outstanding |
|
3,646.9
|
3,391.6
|
|
| Long-term Debt, Fair Value |
|
3,209.7
|
2,870.9
|
|
| Equity units [Member] |
|
|
|
|
| Book Values and Fair Values of Long - term Debt |
|
|
|
|
| Long-term Debt, Fair Value |
|
$ 0.0
|
$ 877.0
|
|
|
|