Benefit Plans 1 (Details) - USD ($)
$ in Millions |
12 Months Ended |
Dec. 31, 2023 |
Dec. 31, 2022 |
Dec. 31, 2021 |
| Pension Plans [Member] |
|
|
|
|
| Actuarial Assumptions for Benefit Obligations |
|
|
|
|
| Discount Rate |
|
5.15%
|
5.50%
|
|
| Interest Crediting Rate |
|
4.00%
|
4.25%
|
|
| Rate of Compensation Increase |
[1] |
5.05%
|
5.05%
|
|
| Actuarial Assumptions for Net Periodic Benefit Costs |
|
|
|
|
| Discount Rate |
|
5.50%
|
2.90%
|
2.50%
|
| Interest Crediting Rate |
|
4.25%
|
4.00%
|
4.00%
|
| Expected Return on Plan Assets |
|
7.50%
|
5.25%
|
4.75%
|
| Rate of Compensation Increase |
[2] |
5.05%
|
5.05%
|
5.10%
|
| Change in Benefit Obligation |
|
|
|
|
| Benefit Obligation as of January 1 |
|
$ 4,072.7
|
$ 5,187.0
|
|
| Service Cost |
|
94.3
|
123.1
|
$ 129.2
|
| Interest Cost |
|
219.2
|
148.2
|
137.2
|
| Actuarial (Gain) Loss |
|
144.0
|
(983.4)
|
|
| Benefit Payments |
|
(368.6)
|
(402.2)
|
|
| Benefit Obligation as of December 31 |
|
4,161.6
|
4,072.7
|
5,187.0
|
| Change in Fair Value of Plan Assets |
|
|
|
|
| Fair Value of Plan Assets as of January 1 |
|
4,124.7
|
5,352.9
|
|
| Actual Gain (Loss) on Plan Assets |
|
353.8
|
(833.7)
|
|
| Company Contributions |
|
8.3
|
7.7
|
|
| Benefit Payments |
|
(368.6)
|
(402.2)
|
|
| Fair Value of Plan Assets as of December 31 |
|
4,118.2
|
4,124.7
|
$ 5,352.9
|
| Funded (Underfunded) Status as of December 31 |
|
(43.4)
|
52.0
|
|
| Benefit Amounts Recognized on the Balance Sheets |
|
|
|
|
| Other Noncurrent Assets - Employee Benefits and Pension Assets |
|
17.3
|
113.4
|
|
| Other Current Liabilities - Accrued Short-term Benefit Liability |
|
(6.7)
|
(6.3)
|
|
| Other Noncurrent Liabilities - Employee Benefits and Pension Obligations |
|
(54.0)
|
(55.1)
|
|
| Funded (Underfunded) Status |
|
(43.4)
|
52.0
|
|
| Components |
|
|
|
|
| Net Actuarial Loss |
|
1,063.4
|
935.6
|
|
| Prior Service Cost (Credit) |
|
0.2
|
0.2
|
|
| Components of Change in Amounts Included in AOCI and Regulatory Assets |
|
|
|
|
| Actuarial (Gain) Loss During the Year |
|
129.2
|
103.9
|
|
| Amortization of Actuarial Gain (Loss) |
|
(1.4)
|
(63.0)
|
|
| Change for the Year |
|
$ 127.8
|
$ 40.9
|
|
| Benefit Plans (Textuals) [Abstract] |
|
|
|
|
| Rate of Compensation Increase |
[1] |
5.05%
|
5.05%
|
|
| Company Contributions |
|
$ 8.3
|
$ 7.7
|
|
| Pension Plans [Member] | Regulatory Assets [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
938.6
|
841.8
|
|
| Pension Plans [Member] | Deferred Income Taxes [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
26.4
|
19.9
|
|
| Pension Plans [Member] | Net of Tax AOCI [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
$ 98.6
|
$ 74.1
|
|
| Pension Plans [Member] | AEP Texas Inc. [Member] |
|
|
|
|
| Actuarial Assumptions for Benefit Obligations |
|
|
|
|
| Discount Rate |
|
5.15%
|
5.50%
|
|
| Interest Crediting Rate |
|
4.00%
|
4.25%
|
|
| Rate of Compensation Increase |
[1] |
5.20%
|
5.15%
|
|
| Actuarial Assumptions for Net Periodic Benefit Costs |
|
|
|
|
| Discount Rate |
|
5.50%
|
2.90%
|
2.50%
|
| Interest Crediting Rate |
|
4.25%
|
4.00%
|
4.00%
|
| Expected Return on Plan Assets |
|
7.50%
|
5.25%
|
4.75%
|
| Rate of Compensation Increase |
[2] |
5.20%
|
5.15%
|
5.10%
|
| Change in Benefit Obligation |
|
|
|
|
| Benefit Obligation as of January 1 |
|
$ 334.1
|
$ 419.8
|
|
| Service Cost |
|
8.2
|
11.1
|
$ 11.8
|
| Interest Cost |
|
18.3
|
12.1
|
11.2
|
| Actuarial (Gain) Loss |
|
20.1
|
(67.8)
|
|
| Benefit Payments |
|
(37.6)
|
(41.1)
|
|
| Benefit Obligation as of December 31 |
|
343.1
|
334.1
|
419.8
|
| Change in Fair Value of Plan Assets |
|
|
|
|
| Fair Value of Plan Assets as of January 1 |
|
335.1
|
444.9
|
|
| Actual Gain (Loss) on Plan Assets |
|
34.8
|
(69.2)
|
|
| Company Contributions |
|
0.4
|
0.5
|
|
| Benefit Payments |
|
(37.6)
|
(41.1)
|
|
| Fair Value of Plan Assets as of December 31 |
|
332.7
|
335.1
|
$ 444.9
|
| Funded (Underfunded) Status as of December 31 |
|
(10.4)
|
1.0
|
|
| Benefit Amounts Recognized on the Balance Sheets |
|
|
|
|
| Other Noncurrent Assets - Employee Benefits and Pension Assets |
|
0.1
|
3.7
|
|
| Other Current Liabilities - Accrued Short-term Benefit Liability |
|
(0.3)
|
(0.4)
|
|
| Other Noncurrent Liabilities - Employee Benefits and Pension Obligations |
|
10.2
|
2.3
|
|
| Funded (Underfunded) Status |
|
(10.4)
|
1.0
|
|
| Components |
|
|
|
|
| Net Actuarial Loss |
|
175.2
|
161.9
|
|
| Prior Service Cost (Credit) |
|
0.0
|
0.0
|
|
| Components of Change in Amounts Included in AOCI and Regulatory Assets |
|
|
|
|
| Actuarial (Gain) Loss During the Year |
|
13.4
|
22.4
|
|
| Amortization of Actuarial Gain (Loss) |
|
(0.1)
|
(5.2)
|
|
| Change for the Year |
|
$ 13.3
|
$ 17.2
|
|
| Benefit Plans (Textuals) [Abstract] |
|
|
|
|
| Rate of Compensation Increase |
[1] |
5.20%
|
5.15%
|
|
| Company Contributions |
|
$ 0.4
|
$ 0.5
|
|
| Pension Plans [Member] | AEP Texas Inc. [Member] | Regulatory Assets [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
163.4
|
151.2
|
|
| Pension Plans [Member] | AEP Texas Inc. [Member] | Deferred Income Taxes [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
2.7
|
2.4
|
|
| Pension Plans [Member] | AEP Texas Inc. [Member] | Net of Tax AOCI [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
$ 9.1
|
$ 8.3
|
|
| Pension Plans [Member] | Appalachian Power Co [Member] |
|
|
|
|
| Actuarial Assumptions for Benefit Obligations |
|
|
|
|
| Discount Rate |
|
5.15%
|
5.50%
|
|
| Interest Crediting Rate |
|
4.00%
|
4.25%
|
|
| Rate of Compensation Increase |
[1] |
4.95%
|
4.90%
|
|
| Actuarial Assumptions for Net Periodic Benefit Costs |
|
|
|
|
| Discount Rate |
|
5.50%
|
2.90%
|
2.50%
|
| Interest Crediting Rate |
|
4.25%
|
4.00%
|
4.00%
|
| Expected Return on Plan Assets |
|
7.50%
|
5.25%
|
4.75%
|
| Rate of Compensation Increase |
[2] |
4.95%
|
4.90%
|
4.85%
|
| Change in Benefit Obligation |
|
|
|
|
| Benefit Obligation as of January 1 |
|
$ 485.7
|
$ 621.7
|
|
| Service Cost |
|
9.1
|
11.4
|
$ 11.9
|
| Interest Cost |
|
26.4
|
17.5
|
16.4
|
| Actuarial (Gain) Loss |
|
23.2
|
(123.1)
|
|
| Benefit Payments |
|
(40.3)
|
(41.8)
|
|
| Benefit Obligation as of December 31 |
|
504.1
|
485.7
|
621.7
|
| Change in Fair Value of Plan Assets |
|
|
|
|
| Fair Value of Plan Assets as of January 1 |
|
531.7
|
683.3
|
|
| Actual Gain (Loss) on Plan Assets |
|
58.4
|
(109.8)
|
|
| Company Contributions |
|
0.0
|
0.0
|
|
| Benefit Payments |
|
(40.3)
|
(41.8)
|
|
| Fair Value of Plan Assets as of December 31 |
|
549.8
|
531.7
|
$ 683.3
|
| Funded (Underfunded) Status as of December 31 |
|
45.7
|
46.0
|
|
| Benefit Amounts Recognized on the Balance Sheets |
|
|
|
|
| Other Noncurrent Assets - Employee Benefits and Pension Assets |
|
46.0
|
46.6
|
|
| Other Current Liabilities - Accrued Short-term Benefit Liability |
|
0.0
|
0.0
|
|
| Other Noncurrent Liabilities - Employee Benefits and Pension Obligations |
|
(0.3)
|
(0.6)
|
|
| Funded (Underfunded) Status |
|
45.7
|
46.0
|
|
| Components |
|
|
|
|
| Net Actuarial Loss |
|
104.9
|
95.6
|
|
| Prior Service Cost (Credit) |
|
0.0
|
0.0
|
|
| Components of Change in Amounts Included in AOCI and Regulatory Assets |
|
|
|
|
| Actuarial (Gain) Loss During the Year |
|
9.3
|
19.1
|
|
| Amortization of Actuarial Gain (Loss) |
|
0.0
|
(7.4)
|
|
| Change for the Year |
|
$ 9.3
|
$ 11.7
|
|
| Benefit Plans (Textuals) [Abstract] |
|
|
|
|
| Rate of Compensation Increase |
[1] |
4.95%
|
4.90%
|
|
| Company Contributions |
|
$ 0.0
|
$ 0.0
|
|
| Pension Plans [Member] | Appalachian Power Co [Member] | Regulatory Assets [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
102.6
|
93.6
|
|
| Pension Plans [Member] | Appalachian Power Co [Member] | Deferred Income Taxes [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
0.4
|
0.4
|
|
| Pension Plans [Member] | Appalachian Power Co [Member] | Net of Tax AOCI [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
$ 1.9
|
$ 1.6
|
|
| Pension Plans [Member] | Indiana Michigan Power Co [Member] |
|
|
|
|
| Actuarial Assumptions for Benefit Obligations |
|
|
|
|
| Discount Rate |
|
5.15%
|
5.50%
|
|
| Interest Crediting Rate |
|
4.00%
|
4.25%
|
|
| Rate of Compensation Increase |
[1] |
5.05%
|
5.00%
|
|
| Actuarial Assumptions for Net Periodic Benefit Costs |
|
|
|
|
| Discount Rate |
|
5.50%
|
2.90%
|
2.50%
|
| Interest Crediting Rate |
|
4.25%
|
4.00%
|
4.00%
|
| Expected Return on Plan Assets |
|
7.50%
|
5.25%
|
4.75%
|
| Rate of Compensation Increase |
[2] |
5.05%
|
5.00%
|
5.00%
|
| Change in Benefit Obligation |
|
|
|
|
| Benefit Obligation as of January 1 |
|
$ 466.8
|
$ 612.1
|
|
| Service Cost |
|
11.9
|
16.2
|
$ 17.5
|
| Interest Cost |
|
24.9
|
17.0
|
16.2
|
| Actuarial (Gain) Loss |
|
8.5
|
(138.0)
|
|
| Benefit Payments |
|
(35.1)
|
(40.5)
|
|
| Benefit Obligation as of December 31 |
|
477.0
|
466.8
|
612.1
|
| Change in Fair Value of Plan Assets |
|
|
|
|
| Fair Value of Plan Assets as of January 1 |
|
533.7
|
681.5
|
|
| Actual Gain (Loss) on Plan Assets |
|
51.5
|
(107.4)
|
|
| Company Contributions |
|
0.5
|
0.1
|
|
| Benefit Payments |
|
(35.1)
|
(40.5)
|
|
| Fair Value of Plan Assets as of December 31 |
|
550.6
|
533.7
|
$ 681.5
|
| Funded (Underfunded) Status as of December 31 |
|
73.6
|
66.9
|
|
| Benefit Amounts Recognized on the Balance Sheets |
|
|
|
|
| Other Noncurrent Assets - Employee Benefits and Pension Assets |
|
74.8
|
68.5
|
|
| Other Current Liabilities - Accrued Short-term Benefit Liability |
|
0.0
|
(0.1)
|
|
| Other Noncurrent Liabilities - Employee Benefits and Pension Obligations |
|
1.2
|
1.5
|
|
| Funded (Underfunded) Status |
|
73.6
|
66.9
|
|
| Components |
|
|
|
|
| Net Actuarial Loss |
|
(5.8)
|
(6.9)
|
|
| Prior Service Cost (Credit) |
|
0.0
|
0.0
|
|
| Components of Change in Amounts Included in AOCI and Regulatory Assets |
|
|
|
|
| Actuarial (Gain) Loss During the Year |
|
1.2
|
1.8
|
|
| Amortization of Actuarial Gain (Loss) |
|
(0.1)
|
(7.1)
|
|
| Change for the Year |
|
$ 1.1
|
$ (5.3)
|
|
| Benefit Plans (Textuals) [Abstract] |
|
|
|
|
| Rate of Compensation Increase |
[1] |
5.05%
|
5.00%
|
|
| Company Contributions |
|
$ 0.5
|
$ 0.1
|
|
| Pension Plans [Member] | Indiana Michigan Power Co [Member] | Regulatory Assets [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
6.4
|
4.8
|
|
| Pension Plans [Member] | Indiana Michigan Power Co [Member] | Deferred Income Taxes [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
(2.6)
|
(2.4)
|
|
| Pension Plans [Member] | Indiana Michigan Power Co [Member] | Net of Tax AOCI [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
$ (9.6)
|
$ (9.3)
|
|
| Pension Plans [Member] | Ohio Power Co [Member] |
|
|
|
|
| Actuarial Assumptions for Benefit Obligations |
|
|
|
|
| Discount Rate |
|
5.15%
|
5.50%
|
|
| Interest Crediting Rate |
|
4.00%
|
4.25%
|
|
| Rate of Compensation Increase |
[1] |
5.45%
|
5.35%
|
|
| Actuarial Assumptions for Net Periodic Benefit Costs |
|
|
|
|
| Discount Rate |
|
5.50%
|
2.90%
|
2.50%
|
| Interest Crediting Rate |
|
4.25%
|
4.00%
|
4.00%
|
| Expected Return on Plan Assets |
|
7.50%
|
5.25%
|
4.75%
|
| Rate of Compensation Increase |
[2] |
5.45%
|
5.35%
|
5.30%
|
| Change in Benefit Obligation |
|
|
|
|
| Benefit Obligation as of January 1 |
|
$ 363.6
|
$ 470.7
|
|
| Service Cost |
|
8.4
|
11.2
|
$ 11.4
|
| Interest Cost |
|
19.8
|
13.3
|
12.5
|
| Actuarial (Gain) Loss |
|
17.5
|
(97.9)
|
|
| Benefit Payments |
|
(30.9)
|
(33.7)
|
|
| Benefit Obligation as of December 31 |
|
378.4
|
363.6
|
470.7
|
| Change in Fair Value of Plan Assets |
|
|
|
|
| Fair Value of Plan Assets as of January 1 |
|
406.4
|
524.8
|
|
| Actual Gain (Loss) on Plan Assets |
|
44.0
|
(84.8)
|
|
| Company Contributions |
|
0.0
|
0.1
|
|
| Benefit Payments |
|
(30.9)
|
(33.7)
|
|
| Fair Value of Plan Assets as of December 31 |
|
419.5
|
406.4
|
$ 524.8
|
| Funded (Underfunded) Status as of December 31 |
|
41.1
|
42.8
|
|
| Benefit Amounts Recognized on the Balance Sheets |
|
|
|
|
| Other Noncurrent Assets - Employee Benefits and Pension Assets |
|
41.4
|
43.1
|
|
| Other Current Liabilities - Accrued Short-term Benefit Liability |
|
0.0
|
0.0
|
|
| Other Noncurrent Liabilities - Employee Benefits and Pension Obligations |
|
0.3
|
0.3
|
|
| Funded (Underfunded) Status |
|
41.1
|
42.8
|
|
| Components |
|
|
|
|
| Net Actuarial Loss |
|
131.9
|
124.3
|
|
| Prior Service Cost (Credit) |
|
0.0
|
0.0
|
|
| Components of Change in Amounts Included in AOCI and Regulatory Assets |
|
|
|
|
| Actuarial (Gain) Loss During the Year |
|
7.6
|
11.7
|
|
| Amortization of Actuarial Gain (Loss) |
|
0.0
|
(5.5)
|
|
| Change for the Year |
|
$ 7.6
|
$ 6.2
|
|
| Benefit Plans (Textuals) [Abstract] |
|
|
|
|
| Rate of Compensation Increase |
[1] |
5.45%
|
5.35%
|
|
| Company Contributions |
|
$ 0.0
|
$ 0.1
|
|
| Pension Plans [Member] | Ohio Power Co [Member] | Regulatory Assets [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
131.9
|
124.3
|
|
| Pension Plans [Member] | Ohio Power Co [Member] | Deferred Income Taxes [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
0.0
|
0.0
|
|
| Pension Plans [Member] | Ohio Power Co [Member] | Net of Tax AOCI [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
$ 0.0
|
$ 0.0
|
|
| Pension Plans [Member] | Public Service Co Of Oklahoma [Member] |
|
|
|
|
| Actuarial Assumptions for Benefit Obligations |
|
|
|
|
| Discount Rate |
|
5.15%
|
5.50%
|
|
| Interest Crediting Rate |
|
4.00%
|
4.25%
|
|
| Rate of Compensation Increase |
[1] |
5.20%
|
5.15%
|
|
| Actuarial Assumptions for Net Periodic Benefit Costs |
|
|
|
|
| Discount Rate |
|
5.50%
|
2.90%
|
2.50%
|
| Interest Crediting Rate |
|
4.25%
|
4.00%
|
4.00%
|
| Expected Return on Plan Assets |
|
7.50%
|
5.25%
|
4.75%
|
| Rate of Compensation Increase |
[2] |
5.20%
|
5.15%
|
5.10%
|
| Change in Benefit Obligation |
|
|
|
|
| Benefit Obligation as of January 1 |
|
$ 192.3
|
$ 252.6
|
|
| Service Cost |
|
5.5
|
7.4
|
$ 8.0
|
| Interest Cost |
|
10.7
|
7.0
|
6.7
|
| Actuarial (Gain) Loss |
|
13.6
|
(52.9)
|
|
| Benefit Payments |
|
(19.9)
|
(21.8)
|
|
| Benefit Obligation as of December 31 |
|
202.2
|
192.3
|
252.6
|
| Change in Fair Value of Plan Assets |
|
|
|
|
| Fair Value of Plan Assets as of January 1 |
|
218.5
|
286.2
|
|
| Actual Gain (Loss) on Plan Assets |
|
24.0
|
(46.0)
|
|
| Company Contributions |
|
0.1
|
0.1
|
|
| Benefit Payments |
|
(19.9)
|
(21.8)
|
|
| Fair Value of Plan Assets as of December 31 |
|
222.7
|
218.5
|
$ 286.2
|
| Funded (Underfunded) Status as of December 31 |
|
20.5
|
26.2
|
|
| Benefit Amounts Recognized on the Balance Sheets |
|
|
|
|
| Other Noncurrent Assets - Employee Benefits and Pension Assets |
|
21.8
|
27.6
|
|
| Other Current Liabilities - Accrued Short-term Benefit Liability |
|
(0.1)
|
(0.1)
|
|
| Other Noncurrent Liabilities - Employee Benefits and Pension Obligations |
|
1.2
|
1.3
|
|
| Funded (Underfunded) Status |
|
20.5
|
26.2
|
|
| Components |
|
|
|
|
| Net Actuarial Loss |
|
46.7
|
38.8
|
|
| Prior Service Cost (Credit) |
|
0.0
|
0.0
|
|
| Components of Change in Amounts Included in AOCI and Regulatory Assets |
|
|
|
|
| Actuarial (Gain) Loss During the Year |
|
7.9
|
6.7
|
|
| Amortization of Actuarial Gain (Loss) |
|
0.0
|
(2.9)
|
|
| Change for the Year |
|
$ 7.9
|
$ 3.8
|
|
| Benefit Plans (Textuals) [Abstract] |
|
|
|
|
| Rate of Compensation Increase |
[1] |
5.20%
|
5.15%
|
|
| Company Contributions |
|
$ 0.1
|
$ 0.1
|
|
| Pension Plans [Member] | Public Service Co Of Oklahoma [Member] | Regulatory Assets [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
46.7
|
38.8
|
|
| Pension Plans [Member] | Public Service Co Of Oklahoma [Member] | Deferred Income Taxes [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
0.0
|
0.0
|
|
| Pension Plans [Member] | Public Service Co Of Oklahoma [Member] | Net of Tax AOCI [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
$ 0.0
|
$ 0.0
|
|
| Pension Plans [Member] | Southwestern Electric Power Co [Member] |
|
|
|
|
| Actuarial Assumptions for Benefit Obligations |
|
|
|
|
| Discount Rate |
|
5.15%
|
5.50%
|
|
| Interest Crediting Rate |
|
4.00%
|
4.25%
|
|
| Rate of Compensation Increase |
[1] |
5.00%
|
5.00%
|
|
| Actuarial Assumptions for Net Periodic Benefit Costs |
|
|
|
|
| Discount Rate |
|
5.50%
|
2.90%
|
2.50%
|
| Interest Crediting Rate |
|
4.25%
|
4.00%
|
4.00%
|
| Expected Return on Plan Assets |
|
7.50%
|
5.25%
|
4.75%
|
| Rate of Compensation Increase |
[2] |
5.00%
|
5.00%
|
4.95%
|
| Change in Benefit Obligation |
|
|
|
|
| Benefit Obligation as of January 1 |
|
$ 250.7
|
$ 317.7
|
|
| Service Cost |
|
7.7
|
10.6
|
$ 11.2
|
| Interest Cost |
|
13.9
|
9.1
|
8.5
|
| Actuarial (Gain) Loss |
|
16.8
|
(57.9)
|
|
| Benefit Payments |
|
(27.9)
|
(28.8)
|
|
| Benefit Obligation as of December 31 |
|
261.2
|
250.7
|
317.7
|
| Change in Fair Value of Plan Assets |
|
|
|
|
| Fair Value of Plan Assets as of January 1 |
|
231.3
|
308.3
|
|
| Actual Gain (Loss) on Plan Assets |
|
23.9
|
(48.3)
|
|
| Company Contributions |
|
0.2
|
0.1
|
|
| Benefit Payments |
|
(27.9)
|
(28.8)
|
|
| Fair Value of Plan Assets as of December 31 |
|
227.5
|
231.3
|
$ 308.3
|
| Funded (Underfunded) Status as of December 31 |
|
(33.7)
|
(19.4)
|
|
| Benefit Amounts Recognized on the Balance Sheets |
|
|
|
|
| Other Noncurrent Assets - Employee Benefits and Pension Assets |
|
0.0
|
0.0
|
|
| Other Current Liabilities - Accrued Short-term Benefit Liability |
|
(0.1)
|
(0.1)
|
|
| Other Noncurrent Liabilities - Employee Benefits and Pension Obligations |
|
(33.6)
|
(19.3)
|
|
| Funded (Underfunded) Status |
|
(33.7)
|
(19.4)
|
|
| Components |
|
|
|
|
| Net Actuarial Loss |
|
89.6
|
77.6
|
|
| Prior Service Cost (Credit) |
|
0.0
|
0.0
|
|
| Components of Change in Amounts Included in AOCI and Regulatory Assets |
|
|
|
|
| Actuarial (Gain) Loss During the Year |
|
12.1
|
5.0
|
|
| Amortization of Actuarial Gain (Loss) |
|
(0.1)
|
(3.8)
|
|
| Change for the Year |
|
$ 12.0
|
$ 1.2
|
|
| Benefit Plans (Textuals) [Abstract] |
|
|
|
|
| Rate of Compensation Increase |
[1] |
5.00%
|
5.00%
|
|
| Company Contributions |
|
$ 0.2
|
$ 0.1
|
|
| Pension Plans [Member] | Southwestern Electric Power Co [Member] | Regulatory Assets [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
89.7
|
77.6
|
|
| Pension Plans [Member] | Southwestern Electric Power Co [Member] | Deferred Income Taxes [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
0.0
|
0.0
|
|
| Pension Plans [Member] | Southwestern Electric Power Co [Member] | Net of Tax AOCI [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
$ (0.1)
|
0.0
|
|
| Pension Plans [Member] | Minimum [Member] |
|
|
|
|
| Actuarial Assumptions for Benefit Obligations |
|
|
|
|
| Rate of Compensation Increase |
|
3.00%
|
|
|
| Benefit Plans (Textuals) [Abstract] |
|
|
|
|
| Rate of Compensation Increase |
|
3.00%
|
|
|
| Pension Plans [Member] | Minimum [Member] | AEP Texas Inc. [Member] |
|
|
|
|
| Actuarial Assumptions for Benefit Obligations |
|
|
|
|
| Rate of Compensation Increase |
|
3.00%
|
|
|
| Benefit Plans (Textuals) [Abstract] |
|
|
|
|
| Rate of Compensation Increase |
|
3.00%
|
|
|
| Pension Plans [Member] | Minimum [Member] | Appalachian Power Co [Member] |
|
|
|
|
| Actuarial Assumptions for Benefit Obligations |
|
|
|
|
| Rate of Compensation Increase |
|
3.00%
|
|
|
| Benefit Plans (Textuals) [Abstract] |
|
|
|
|
| Rate of Compensation Increase |
|
3.00%
|
|
|
| Pension Plans [Member] | Minimum [Member] | Indiana Michigan Power Co [Member] |
|
|
|
|
| Actuarial Assumptions for Benefit Obligations |
|
|
|
|
| Rate of Compensation Increase |
|
3.00%
|
|
|
| Benefit Plans (Textuals) [Abstract] |
|
|
|
|
| Rate of Compensation Increase |
|
3.00%
|
|
|
| Pension Plans [Member] | Minimum [Member] | Ohio Power Co [Member] |
|
|
|
|
| Actuarial Assumptions for Benefit Obligations |
|
|
|
|
| Rate of Compensation Increase |
|
3.00%
|
|
|
| Benefit Plans (Textuals) [Abstract] |
|
|
|
|
| Rate of Compensation Increase |
|
3.00%
|
|
|
| Pension Plans [Member] | Minimum [Member] | Public Service Co Of Oklahoma [Member] |
|
|
|
|
| Actuarial Assumptions for Benefit Obligations |
|
|
|
|
| Rate of Compensation Increase |
|
3.00%
|
|
|
| Benefit Plans (Textuals) [Abstract] |
|
|
|
|
| Rate of Compensation Increase |
|
3.00%
|
|
|
| Pension Plans [Member] | Minimum [Member] | Southwestern Electric Power Co [Member] |
|
|
|
|
| Actuarial Assumptions for Benefit Obligations |
|
|
|
|
| Rate of Compensation Increase |
|
3.00%
|
|
|
| Benefit Plans (Textuals) [Abstract] |
|
|
|
|
| Rate of Compensation Increase |
|
3.00%
|
|
|
| Pension Plans [Member] | Maximum [Member] |
|
|
|
|
| Actuarial Assumptions for Benefit Obligations |
|
|
|
|
| Rate of Compensation Increase |
|
11.50%
|
|
|
| Benefit Plans (Textuals) [Abstract] |
|
|
|
|
| Rate of Compensation Increase |
|
11.50%
|
|
|
| Pension Plans [Member] | Maximum [Member] | AEP Texas Inc. [Member] |
|
|
|
|
| Actuarial Assumptions for Benefit Obligations |
|
|
|
|
| Rate of Compensation Increase |
|
11.50%
|
|
|
| Benefit Plans (Textuals) [Abstract] |
|
|
|
|
| Rate of Compensation Increase |
|
11.50%
|
|
|
| Pension Plans [Member] | Maximum [Member] | Appalachian Power Co [Member] |
|
|
|
|
| Actuarial Assumptions for Benefit Obligations |
|
|
|
|
| Rate of Compensation Increase |
|
11.50%
|
|
|
| Benefit Plans (Textuals) [Abstract] |
|
|
|
|
| Rate of Compensation Increase |
|
11.50%
|
|
|
| Pension Plans [Member] | Maximum [Member] | Indiana Michigan Power Co [Member] |
|
|
|
|
| Actuarial Assumptions for Benefit Obligations |
|
|
|
|
| Rate of Compensation Increase |
|
11.50%
|
|
|
| Benefit Plans (Textuals) [Abstract] |
|
|
|
|
| Rate of Compensation Increase |
|
11.50%
|
|
|
| Pension Plans [Member] | Maximum [Member] | Ohio Power Co [Member] |
|
|
|
|
| Actuarial Assumptions for Benefit Obligations |
|
|
|
|
| Rate of Compensation Increase |
|
11.50%
|
|
|
| Benefit Plans (Textuals) [Abstract] |
|
|
|
|
| Rate of Compensation Increase |
|
11.50%
|
|
|
| Pension Plans [Member] | Maximum [Member] | Public Service Co Of Oklahoma [Member] |
|
|
|
|
| Actuarial Assumptions for Benefit Obligations |
|
|
|
|
| Rate of Compensation Increase |
|
11.50%
|
|
|
| Benefit Plans (Textuals) [Abstract] |
|
|
|
|
| Rate of Compensation Increase |
|
11.50%
|
|
|
| Pension Plans [Member] | Maximum [Member] | Southwestern Electric Power Co [Member] |
|
|
|
|
| Actuarial Assumptions for Benefit Obligations |
|
|
|
|
| Rate of Compensation Increase |
|
11.50%
|
|
|
| Benefit Plans (Textuals) [Abstract] |
|
|
|
|
| Rate of Compensation Increase |
|
11.50%
|
|
|
| Nonqualified Pension Plans [Member] |
|
|
|
|
| Change in Benefit Obligation |
|
|
|
|
| Benefit Obligation as of January 1 |
|
$ 61.5
|
|
|
| Benefit Obligation as of December 31 |
|
60.7
|
61.5
|
|
| Change in Fair Value of Plan Assets |
|
|
|
|
| Fair Value of Plan Assets as of January 1 |
|
0.0
|
|
|
| Company Contributions |
|
8.0
|
8.0
|
|
| Fair Value of Plan Assets as of December 31 |
|
0.0
|
0.0
|
|
| Benefit Plans (Textuals) [Abstract] |
|
|
|
|
| Company Contributions |
|
8.0
|
8.0
|
|
| Nonqualified Pension Plans [Member] | AEP Texas Inc. [Member] |
|
|
|
|
| Change in Benefit Obligation |
|
|
|
|
| Benefit Obligation as of January 1 |
|
2.7
|
|
|
| Benefit Obligation as of December 31 |
|
|
2.7
|
|
| Change in Fair Value of Plan Assets |
|
|
|
|
| Fair Value of Plan Assets as of January 1 |
|
0.0
|
|
|
| Fair Value of Plan Assets as of December 31 |
|
0.0
|
0.0
|
|
| Nonqualified Pension Plans [Member] | Appalachian Power Co [Member] |
|
|
|
|
| Change in Benefit Obligation |
|
|
|
|
| Benefit Obligation as of January 1 |
|
0.6
|
|
|
| Benefit Obligation as of December 31 |
|
0.4
|
0.6
|
|
| Change in Fair Value of Plan Assets |
|
|
|
|
| Fair Value of Plan Assets as of January 1 |
|
0.0
|
|
|
| Fair Value of Plan Assets as of December 31 |
|
0.0
|
0.0
|
|
| Nonqualified Pension Plans [Member] | Indiana Michigan Power Co [Member] |
|
|
|
|
| Change in Benefit Obligation |
|
|
|
|
| Benefit Obligation as of January 1 |
|
1.6
|
|
|
| Benefit Obligation as of December 31 |
|
1.2
|
1.6
|
|
| Change in Fair Value of Plan Assets |
|
|
|
|
| Fair Value of Plan Assets as of January 1 |
|
0.0
|
|
|
| Fair Value of Plan Assets as of December 31 |
|
0.0
|
0.0
|
|
| Nonqualified Pension Plans [Member] | Ohio Power Co [Member] |
|
|
|
|
| Change in Benefit Obligation |
|
|
|
|
| Benefit Obligation as of January 1 |
|
0.3
|
|
|
| Benefit Obligation as of December 31 |
|
0.3
|
0.3
|
|
| Change in Fair Value of Plan Assets |
|
|
|
|
| Fair Value of Plan Assets as of January 1 |
|
0.0
|
|
|
| Fair Value of Plan Assets as of December 31 |
|
0.0
|
0.0
|
|
| Nonqualified Pension Plans [Member] | Public Service Co Of Oklahoma [Member] |
|
|
|
|
| Change in Benefit Obligation |
|
|
|
|
| Benefit Obligation as of January 1 |
|
1.5
|
|
|
| Benefit Obligation as of December 31 |
|
1.4
|
1.5
|
|
| Change in Fair Value of Plan Assets |
|
|
|
|
| Fair Value of Plan Assets as of January 1 |
|
0.0
|
|
|
| Fair Value of Plan Assets as of December 31 |
|
0.0
|
0.0
|
|
| Nonqualified Pension Plans [Member] | Southwestern Electric Power Co [Member] |
|
|
|
|
| Change in Fair Value of Plan Assets |
|
|
|
|
| Fair Value of Plan Assets as of January 1 |
|
231.3
|
|
|
| Fair Value of Plan Assets as of December 31 |
|
$ 227.5
|
$ 231.3
|
|
| Other Postretirement Benefit Plans [Member] |
|
|
|
|
| Actuarial Assumptions for Benefit Obligations |
|
|
|
|
| Discount Rate |
|
5.15%
|
5.50%
|
|
| Actuarial Assumptions for Net Periodic Benefit Costs |
|
|
|
|
| Discount Rate |
|
5.50%
|
2.90%
|
2.55%
|
| Expected Return on Plan Assets |
|
7.25%
|
5.50%
|
4.75%
|
| Health Care Trend Rates |
|
|
|
|
| Initial |
|
7.00%
|
7.50%
|
|
| Ultimate |
|
4.50%
|
4.50%
|
|
| Year Ultimate Reached |
|
2030
|
2029
|
|
| Change in Benefit Obligation |
|
|
|
|
| Benefit Obligation as of January 1 |
|
$ 872.6
|
$ 1,041.3
|
|
| Service Cost |
|
4.6
|
7.4
|
$ 9.5
|
| Interest Cost |
|
46.2
|
29.2
|
30.5
|
| Actuarial (Gain) Loss |
|
19.8
|
(109.8)
|
|
| Benefit Payments |
|
(137.8)
|
(140.1)
|
|
| Participant Contributions |
|
43.6
|
44.1
|
|
| Medicare Subsidy |
|
0.5
|
0.5
|
|
| Benefit Obligation as of December 31 |
|
849.5
|
872.6
|
1,041.3
|
| Change in Fair Value of Plan Assets |
|
|
|
|
| Fair Value of Plan Assets as of January 1 |
|
1,549.3
|
2,044.3
|
|
| Actual Gain (Loss) on Plan Assets |
|
213.2
|
(403.6)
|
|
| Company Contributions |
|
5.0
|
4.6
|
|
| Participant Contributions |
|
43.6
|
44.1
|
|
| Benefit Payments |
|
(137.8)
|
(140.1)
|
|
| Fair Value of Plan Assets as of December 31 |
|
1,673.3
|
1,549.3
|
$ 2,044.3
|
| Funded (Underfunded) Status as of December 31 |
|
823.8
|
676.7
|
|
| Benefit Amounts Recognized on the Balance Sheets |
|
|
|
|
| Other Noncurrent Assets - Employee Benefits and Pension Assets |
|
838.0
|
699.5
|
|
| Other Current Liabilities - Accrued Short-term Benefit Liability |
|
(2.4)
|
(2.5)
|
|
| Other Noncurrent Liabilities - Employee Benefits and Pension Obligations |
|
(11.8)
|
(20.3)
|
|
| Funded (Underfunded) Status |
|
823.8
|
676.7
|
|
| Components |
|
|
|
|
| Net Actuarial Loss |
|
201.5
|
300.0
|
|
| Prior Service Cost (Credit) |
|
(27.4)
|
(90.5)
|
|
| Components of Change in Amounts Included in AOCI and Regulatory Assets |
|
|
|
|
| Actuarial (Gain) Loss During the Year |
|
(83.7)
|
403.6
|
|
| Amortization of Actuarial Gain (Loss) |
|
(14.8)
|
|
|
| Amortization of Prior Service Credit (Cost) |
|
63.1
|
71.4
|
|
| Change for the Year |
|
(35.4)
|
475.0
|
|
| Benefit Plans (Textuals) [Abstract] |
|
|
|
|
| Company Contributions |
|
5.0
|
4.6
|
|
| Other Postretirement Benefit Plans [Member] | Regulatory Assets [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
106.1
|
126.0
|
|
| Other Postretirement Benefit Plans [Member] | Deferred Income Taxes [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
14.3
|
17.5
|
|
| Other Postretirement Benefit Plans [Member] | Net of Tax AOCI [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
$ 53.7
|
$ 66.0
|
|
| Other Postretirement Benefit Plans [Member] | AEP Texas Inc. [Member] |
|
|
|
|
| Actuarial Assumptions for Benefit Obligations |
|
|
|
|
| Discount Rate |
|
5.15%
|
5.50%
|
|
| Actuarial Assumptions for Net Periodic Benefit Costs |
|
|
|
|
| Discount Rate |
|
5.50%
|
2.90%
|
2.55%
|
| Expected Return on Plan Assets |
|
7.25%
|
5.50%
|
4.75%
|
| Health Care Trend Rates |
|
|
|
|
| Initial |
|
7.00%
|
7.50%
|
|
| Ultimate |
|
4.50%
|
4.50%
|
|
| Year Ultimate Reached |
|
2030
|
2029
|
|
| Change in Benefit Obligation |
|
|
|
|
| Benefit Obligation as of January 1 |
|
$ 68.6
|
$ 80.5
|
|
| Service Cost |
|
0.3
|
0.5
|
$ 0.7
|
| Interest Cost |
|
3.6
|
2.2
|
2.4
|
| Actuarial (Gain) Loss |
|
1.2
|
(7.1)
|
|
| Benefit Payments |
|
(10.7)
|
(10.9)
|
|
| Participant Contributions |
|
3.4
|
3.4
|
|
| Medicare Subsidy |
|
0.0
|
0.0
|
|
| Benefit Obligation as of December 31 |
|
66.4
|
68.6
|
80.5
|
| Change in Fair Value of Plan Assets |
|
|
|
|
| Fair Value of Plan Assets as of January 1 |
|
128.3
|
168.8
|
|
| Actual Gain (Loss) on Plan Assets |
|
16.5
|
(33.0)
|
|
| Company Contributions |
|
0.0
|
0.0
|
|
| Participant Contributions |
|
3.4
|
3.4
|
|
| Benefit Payments |
|
(10.7)
|
(10.9)
|
|
| Fair Value of Plan Assets as of December 31 |
|
137.5
|
128.3
|
$ 168.8
|
| Funded (Underfunded) Status as of December 31 |
|
71.1
|
59.7
|
|
| Benefit Amounts Recognized on the Balance Sheets |
|
|
|
|
| Other Noncurrent Assets - Employee Benefits and Pension Assets |
|
71.1
|
59.7
|
|
| Other Current Liabilities - Accrued Short-term Benefit Liability |
|
0.0
|
0.0
|
|
| Other Noncurrent Liabilities - Employee Benefits and Pension Obligations |
|
0.0
|
0.0
|
|
| Funded (Underfunded) Status |
|
71.1
|
59.7
|
|
| Components |
|
|
|
|
| Net Actuarial Loss |
|
22.1
|
29.7
|
|
| Prior Service Cost (Credit) |
|
(2.3)
|
(7.6)
|
|
| Components of Change in Amounts Included in AOCI and Regulatory Assets |
|
|
|
|
| Actuarial (Gain) Loss During the Year |
|
(6.4)
|
34.9
|
|
| Amortization of Actuarial Gain (Loss) |
|
(1.2)
|
|
|
| Amortization of Prior Service Credit (Cost) |
|
5.3
|
6.1
|
|
| Change for the Year |
|
(2.3)
|
41.0
|
|
| Benefit Plans (Textuals) [Abstract] |
|
|
|
|
| Company Contributions |
|
0.0
|
0.0
|
|
| Other Postretirement Benefit Plans [Member] | AEP Texas Inc. [Member] | Regulatory Assets [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
19.8
|
22.0
|
|
| Other Postretirement Benefit Plans [Member] | AEP Texas Inc. [Member] | Deferred Income Taxes [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
0.0
|
0.1
|
|
| Other Postretirement Benefit Plans [Member] | AEP Texas Inc. [Member] | Net of Tax AOCI [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
$ 0.0
|
$ 0.0
|
|
| Other Postretirement Benefit Plans [Member] | Appalachian Power Co [Member] |
|
|
|
|
| Actuarial Assumptions for Benefit Obligations |
|
|
|
|
| Discount Rate |
|
5.15%
|
5.50%
|
|
| Actuarial Assumptions for Net Periodic Benefit Costs |
|
|
|
|
| Discount Rate |
|
5.50%
|
2.90%
|
2.55%
|
| Expected Return on Plan Assets |
|
7.25%
|
5.50%
|
4.75%
|
| Health Care Trend Rates |
|
|
|
|
| Initial |
|
7.00%
|
7.50%
|
|
| Ultimate |
|
4.50%
|
4.50%
|
|
| Year Ultimate Reached |
|
2030
|
2029
|
|
| Change in Benefit Obligation |
|
|
|
|
| Benefit Obligation as of January 1 |
|
$ 140.7
|
$ 167.3
|
|
| Service Cost |
|
0.5
|
0.8
|
$ 1.0
|
| Interest Cost |
|
7.4
|
4.7
|
4.9
|
| Actuarial (Gain) Loss |
|
0.9
|
(16.2)
|
|
| Benefit Payments |
|
(21.6)
|
(23.0)
|
|
| Participant Contributions |
|
6.6
|
7.0
|
|
| Medicare Subsidy |
|
0.1
|
0.1
|
|
| Benefit Obligation as of December 31 |
|
134.6
|
140.7
|
167.3
|
| Change in Fair Value of Plan Assets |
|
|
|
|
| Fair Value of Plan Assets as of January 1 |
|
228.6
|
302.3
|
|
| Actual Gain (Loss) on Plan Assets |
|
28.1
|
(59.3)
|
|
| Company Contributions |
|
1.3
|
1.6
|
|
| Participant Contributions |
|
6.6
|
7.0
|
|
| Benefit Payments |
|
(21.6)
|
(23.0)
|
|
| Fair Value of Plan Assets as of December 31 |
|
243.0
|
228.6
|
$ 302.3
|
| Funded (Underfunded) Status as of December 31 |
|
108.4
|
87.9
|
|
| Benefit Amounts Recognized on the Balance Sheets |
|
|
|
|
| Other Noncurrent Assets - Employee Benefits and Pension Assets |
|
125.6
|
106.3
|
|
| Other Current Liabilities - Accrued Short-term Benefit Liability |
|
(1.6)
|
(1.6)
|
|
| Other Noncurrent Liabilities - Employee Benefits and Pension Obligations |
|
(15.6)
|
(16.8)
|
|
| Funded (Underfunded) Status |
|
108.4
|
87.9
|
|
| Components |
|
|
|
|
| Net Actuarial Loss |
|
27.1
|
40.5
|
|
| Prior Service Cost (Credit) |
|
(4.2)
|
(13.4)
|
|
| Components of Change in Amounts Included in AOCI and Regulatory Assets |
|
|
|
|
| Actuarial (Gain) Loss During the Year |
|
(11.1)
|
59.4
|
|
| Amortization of Actuarial Gain (Loss) |
|
(2.3)
|
|
|
| Amortization of Prior Service Credit (Cost) |
|
9.2
|
10.4
|
|
| Change for the Year |
|
(4.2)
|
69.8
|
|
| Benefit Plans (Textuals) [Abstract] |
|
|
|
|
| Company Contributions |
|
1.3
|
1.6
|
|
| Other Postretirement Benefit Plans [Member] | Appalachian Power Co [Member] | Regulatory Assets [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
13.2
|
14.7
|
|
| Other Postretirement Benefit Plans [Member] | Appalachian Power Co [Member] | Deferred Income Taxes [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
2.0
|
2.5
|
|
| Other Postretirement Benefit Plans [Member] | Appalachian Power Co [Member] | Net of Tax AOCI [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
$ 7.7
|
$ 9.9
|
|
| Other Postretirement Benefit Plans [Member] | Indiana Michigan Power Co [Member] |
|
|
|
|
| Actuarial Assumptions for Benefit Obligations |
|
|
|
|
| Discount Rate |
|
5.15%
|
5.50%
|
|
| Actuarial Assumptions for Net Periodic Benefit Costs |
|
|
|
|
| Discount Rate |
|
5.50%
|
2.90%
|
2.55%
|
| Expected Return on Plan Assets |
|
7.25%
|
5.50%
|
4.75%
|
| Health Care Trend Rates |
|
|
|
|
| Initial |
|
7.00%
|
7.50%
|
|
| Ultimate |
|
4.50%
|
4.50%
|
|
| Year Ultimate Reached |
|
2030
|
2029
|
|
| Change in Benefit Obligation |
|
|
|
|
| Benefit Obligation as of January 1 |
|
$ 101.9
|
$ 118.6
|
|
| Service Cost |
|
0.6
|
0.9
|
$ 1.3
|
| Interest Cost |
|
5.4
|
3.4
|
3.5
|
| Actuarial (Gain) Loss |
|
3.2
|
(8.7)
|
|
| Benefit Payments |
|
(18.3)
|
(18.3)
|
|
| Participant Contributions |
|
6.0
|
6.0
|
|
| Medicare Subsidy |
|
0.0
|
0.0
|
|
| Benefit Obligation as of December 31 |
|
98.8
|
101.9
|
118.6
|
| Change in Fair Value of Plan Assets |
|
|
|
|
| Fair Value of Plan Assets as of January 1 |
|
190.5
|
248.7
|
|
| Actual Gain (Loss) on Plan Assets |
|
26.4
|
(45.9)
|
|
| Company Contributions |
|
0.0
|
0.0
|
|
| Participant Contributions |
|
6.0
|
6.0
|
|
| Benefit Payments |
|
(18.3)
|
(18.3)
|
|
| Fair Value of Plan Assets as of December 31 |
|
204.6
|
190.5
|
$ 248.7
|
| Funded (Underfunded) Status as of December 31 |
|
105.8
|
88.6
|
|
| Benefit Amounts Recognized on the Balance Sheets |
|
|
|
|
| Other Noncurrent Assets - Employee Benefits and Pension Assets |
|
105.8
|
88.6
|
|
| Other Current Liabilities - Accrued Short-term Benefit Liability |
|
0.0
|
0.0
|
|
| Other Noncurrent Liabilities - Employee Benefits and Pension Obligations |
|
0.0
|
0.0
|
|
| Funded (Underfunded) Status |
|
105.8
|
88.6
|
|
| Components |
|
|
|
|
| Net Actuarial Loss |
|
28.7
|
40.2
|
|
| Prior Service Cost (Credit) |
|
(3.7)
|
(12.4)
|
|
| Components of Change in Amounts Included in AOCI and Regulatory Assets |
|
|
|
|
| Actuarial (Gain) Loss During the Year |
|
(9.6)
|
50.9
|
|
| Amortization of Actuarial Gain (Loss) |
|
(1.9)
|
|
|
| Amortization of Prior Service Credit (Cost) |
|
8.7
|
9.7
|
|
| Change for the Year |
|
(2.8)
|
60.6
|
|
| Benefit Plans (Textuals) [Abstract] |
|
|
|
|
| Company Contributions |
|
0.0
|
0.0
|
|
| Other Postretirement Benefit Plans [Member] | Indiana Michigan Power Co [Member] | Regulatory Assets [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
19.0
|
22.1
|
|
| Other Postretirement Benefit Plans [Member] | Indiana Michigan Power Co [Member] | Deferred Income Taxes [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
1.3
|
1.2
|
|
| Other Postretirement Benefit Plans [Member] | Indiana Michigan Power Co [Member] | Net of Tax AOCI [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
$ 4.7
|
$ 4.5
|
|
| Other Postretirement Benefit Plans [Member] | Ohio Power Co [Member] |
|
|
|
|
| Actuarial Assumptions for Benefit Obligations |
|
|
|
|
| Discount Rate |
|
5.15%
|
5.50%
|
|
| Actuarial Assumptions for Net Periodic Benefit Costs |
|
|
|
|
| Discount Rate |
|
5.50%
|
2.90%
|
2.55%
|
| Expected Return on Plan Assets |
|
7.25%
|
5.50%
|
4.75%
|
| Health Care Trend Rates |
|
|
|
|
| Initial |
|
7.00%
|
7.50%
|
|
| Ultimate |
|
4.50%
|
4.50%
|
|
| Year Ultimate Reached |
|
2030
|
2029
|
|
| Change in Benefit Obligation |
|
|
|
|
| Benefit Obligation as of January 1 |
|
$ 88.9
|
$ 104.9
|
|
| Service Cost |
|
0.4
|
0.6
|
$ 0.8
|
| Interest Cost |
|
4.7
|
3.0
|
3.0
|
| Actuarial (Gain) Loss |
|
2.2
|
(8.9)
|
|
| Benefit Payments |
|
(15.0)
|
(15.5)
|
|
| Participant Contributions |
|
4.7
|
4.8
|
|
| Medicare Subsidy |
|
0.0
|
0.0
|
|
| Benefit Obligation as of December 31 |
|
85.9
|
88.9
|
104.9
|
| Change in Fair Value of Plan Assets |
|
|
|
|
| Fair Value of Plan Assets as of January 1 |
|
166.2
|
220.0
|
|
| Actual Gain (Loss) on Plan Assets |
|
21.9
|
(43.1)
|
|
| Company Contributions |
|
0.0
|
0.0
|
|
| Participant Contributions |
|
4.7
|
4.8
|
|
| Benefit Payments |
|
(15.0)
|
(15.5)
|
|
| Fair Value of Plan Assets as of December 31 |
|
177.8
|
166.2
|
$ 220.0
|
| Funded (Underfunded) Status as of December 31 |
|
91.9
|
77.3
|
|
| Benefit Amounts Recognized on the Balance Sheets |
|
|
|
|
| Other Noncurrent Assets - Employee Benefits and Pension Assets |
|
91.9
|
77.3
|
|
| Other Current Liabilities - Accrued Short-term Benefit Liability |
|
0.0
|
0.0
|
|
| Other Noncurrent Liabilities - Employee Benefits and Pension Obligations |
|
0.0
|
0.0
|
|
| Funded (Underfunded) Status |
|
91.9
|
77.3
|
|
| Components |
|
|
|
|
| Net Actuarial Loss |
|
18.1
|
27.6
|
|
| Prior Service Cost (Credit) |
|
(2.9)
|
(9.2)
|
|
| Components of Change in Amounts Included in AOCI and Regulatory Assets |
|
|
|
|
| Actuarial (Gain) Loss During the Year |
|
(7.9)
|
46.1
|
|
| Amortization of Actuarial Gain (Loss) |
|
(1.6)
|
|
|
| Amortization of Prior Service Credit (Cost) |
|
6.3
|
7.1
|
|
| Change for the Year |
|
(3.2)
|
53.2
|
|
| Benefit Plans (Textuals) [Abstract] |
|
|
|
|
| Company Contributions |
|
0.0
|
0.0
|
|
| Other Postretirement Benefit Plans [Member] | Ohio Power Co [Member] | Regulatory Assets [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
15.2
|
18.4
|
|
| Other Postretirement Benefit Plans [Member] | Ohio Power Co [Member] | Deferred Income Taxes [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
0.0
|
0.0
|
|
| Other Postretirement Benefit Plans [Member] | Ohio Power Co [Member] | Net of Tax AOCI [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
$ 0.0
|
$ 0.0
|
|
| Other Postretirement Benefit Plans [Member] | Public Service Co Of Oklahoma [Member] |
|
|
|
|
| Actuarial Assumptions for Benefit Obligations |
|
|
|
|
| Discount Rate |
|
5.15%
|
5.50%
|
|
| Actuarial Assumptions for Net Periodic Benefit Costs |
|
|
|
|
| Discount Rate |
|
5.50%
|
2.90%
|
2.55%
|
| Expected Return on Plan Assets |
|
7.25%
|
5.50%
|
4.75%
|
| Health Care Trend Rates |
|
|
|
|
| Initial |
|
7.00%
|
7.50%
|
|
| Ultimate |
|
4.50%
|
4.50%
|
|
| Year Ultimate Reached |
|
2030
|
2029
|
|
| Change in Benefit Obligation |
|
|
|
|
| Benefit Obligation as of January 1 |
|
$ 45.7
|
$ 54.4
|
|
| Service Cost |
|
0.3
|
0.4
|
$ 0.6
|
| Interest Cost |
|
2.4
|
1.5
|
1.6
|
| Actuarial (Gain) Loss |
|
0.4
|
(5.2)
|
|
| Benefit Payments |
|
(7.6)
|
(7.9)
|
|
| Participant Contributions |
|
2.5
|
2.5
|
|
| Medicare Subsidy |
|
0.0
|
0.0
|
|
| Benefit Obligation as of December 31 |
|
43.7
|
45.7
|
54.4
|
| Change in Fair Value of Plan Assets |
|
|
|
|
| Fair Value of Plan Assets as of January 1 |
|
85.4
|
114.0
|
|
| Actual Gain (Loss) on Plan Assets |
|
9.9
|
(23.2)
|
|
| Company Contributions |
|
0.0
|
0.0
|
|
| Participant Contributions |
|
2.5
|
2.5
|
|
| Benefit Payments |
|
(7.6)
|
(7.9)
|
|
| Fair Value of Plan Assets as of December 31 |
|
90.2
|
85.4
|
$ 114.0
|
| Funded (Underfunded) Status as of December 31 |
|
46.5
|
39.7
|
|
| Benefit Amounts Recognized on the Balance Sheets |
|
|
|
|
| Other Noncurrent Assets - Employee Benefits and Pension Assets |
|
46.5
|
39.7
|
|
| Other Current Liabilities - Accrued Short-term Benefit Liability |
|
0.0
|
0.0
|
|
| Other Noncurrent Liabilities - Employee Benefits and Pension Obligations |
|
0.0
|
0.0
|
|
| Funded (Underfunded) Status |
|
46.5
|
39.7
|
|
| Components |
|
|
|
|
| Net Actuarial Loss |
|
17.5
|
22.0
|
|
| Prior Service Cost (Credit) |
|
(1.6)
|
(5.6)
|
|
| Components of Change in Amounts Included in AOCI and Regulatory Assets |
|
|
|
|
| Actuarial (Gain) Loss During the Year |
|
(3.7)
|
24.1
|
|
| Amortization of Actuarial Gain (Loss) |
|
(0.8)
|
|
|
| Amortization of Prior Service Credit (Cost) |
|
4.0
|
4.4
|
|
| Change for the Year |
|
(0.5)
|
28.5
|
|
| Benefit Plans (Textuals) [Abstract] |
|
|
|
|
| Company Contributions |
|
0.0
|
0.0
|
|
| Other Postretirement Benefit Plans [Member] | Public Service Co Of Oklahoma [Member] | Regulatory Assets [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
15.9
|
16.4
|
|
| Other Postretirement Benefit Plans [Member] | Public Service Co Of Oklahoma [Member] | Deferred Income Taxes [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
0.0
|
0.0
|
|
| Other Postretirement Benefit Plans [Member] | Public Service Co Of Oklahoma [Member] | Net of Tax AOCI [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
$ 0.0
|
$ 0.0
|
|
| Other Postretirement Benefit Plans [Member] | Southwestern Electric Power Co [Member] |
|
|
|
|
| Actuarial Assumptions for Benefit Obligations |
|
|
|
|
| Discount Rate |
|
5.15%
|
5.50%
|
|
| Actuarial Assumptions for Net Periodic Benefit Costs |
|
|
|
|
| Discount Rate |
|
5.50%
|
2.90%
|
2.55%
|
| Expected Return on Plan Assets |
|
7.25%
|
5.50%
|
4.75%
|
| Health Care Trend Rates |
|
|
|
|
| Initial |
|
7.00%
|
7.50%
|
|
| Ultimate |
|
4.50%
|
4.50%
|
|
| Year Ultimate Reached |
|
2030
|
2029
|
|
| Change in Benefit Obligation |
|
|
|
|
| Benefit Obligation as of January 1 |
|
$ 55.1
|
$ 65.2
|
|
| Service Cost |
|
0.4
|
0.6
|
$ 0.8
|
| Interest Cost |
|
2.9
|
1.8
|
1.9
|
| Actuarial (Gain) Loss |
|
1.2
|
(6.6)
|
|
| Benefit Payments |
|
(8.8)
|
(8.8)
|
|
| Participant Contributions |
|
2.9
|
2.9
|
|
| Medicare Subsidy |
|
0.0
|
0.0
|
|
| Benefit Obligation as of December 31 |
|
53.7
|
55.1
|
65.2
|
| Change in Fair Value of Plan Assets |
|
|
|
|
| Fair Value of Plan Assets as of January 1 |
|
103.0
|
136.6
|
|
| Actual Gain (Loss) on Plan Assets |
|
14.0
|
(27.7)
|
|
| Company Contributions |
|
0.0
|
0.0
|
|
| Participant Contributions |
|
2.9
|
2.9
|
|
| Benefit Payments |
|
(8.8)
|
(8.8)
|
|
| Fair Value of Plan Assets as of December 31 |
|
111.1
|
103.0
|
$ 136.6
|
| Funded (Underfunded) Status as of December 31 |
|
57.4
|
47.9
|
|
| Benefit Amounts Recognized on the Balance Sheets |
|
|
|
|
| Other Noncurrent Assets - Employee Benefits and Pension Assets |
|
57.4
|
47.9
|
|
| Other Current Liabilities - Accrued Short-term Benefit Liability |
|
0.0
|
0.0
|
|
| Other Noncurrent Liabilities - Employee Benefits and Pension Obligations |
|
0.0
|
0.0
|
|
| Funded (Underfunded) Status |
|
57.4
|
47.9
|
|
| Components |
|
|
|
|
| Net Actuarial Loss |
|
18.4
|
25.0
|
|
| Prior Service Cost (Credit) |
|
(2.1)
|
(7.0)
|
|
| Components of Change in Amounts Included in AOCI and Regulatory Assets |
|
|
|
|
| Actuarial (Gain) Loss During the Year |
|
(5.6)
|
28.5
|
|
| Amortization of Actuarial Gain (Loss) |
|
(1.0)
|
|
|
| Amortization of Prior Service Credit (Cost) |
|
4.9
|
5.3
|
|
| Change for the Year |
|
(1.7)
|
33.8
|
|
| Benefit Plans (Textuals) [Abstract] |
|
|
|
|
| Company Contributions |
|
0.0
|
0.0
|
|
| Other Postretirement Benefit Plans [Member] | Southwestern Electric Power Co [Member] | Regulatory Assets [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
10.2
|
11.2
|
|
| Other Postretirement Benefit Plans [Member] | Southwestern Electric Power Co [Member] | Deferred Income Taxes [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
1.3
|
1.5
|
|
| Other Postretirement Benefit Plans [Member] | Southwestern Electric Power Co [Member] | Net of Tax AOCI [Member] |
|
|
|
|
| Recorded as |
|
|
|
|
| Total of Amounts Included in AOCI, Income Tax Expense and Regulatory Assets |
|
$ 4.8
|
$ 5.3
|
|
|
|