Business Segments (Details) - USD ($) $ in Millions |
3 Months Ended |
9 Months Ended |
|
Sep. 30, 2016 |
Sep. 30, 2015 |
Sep. 30, 2016 |
Sep. 30, 2015 |
Dec. 31, 2015 |
Reportable Segment Information |
|
|
|
|
|
|
Revenues |
|
$ 4,652.2
|
$ 4,431.4
|
$ 12,590.0
|
$ 12,838.5
|
|
Income (Loss) from Continuing Operations |
|
(764.2)
|
511.8
|
245.3
|
1,563.4
|
|
Income (Loss) from Discontinued Operations, Net of Tax |
|
0.0
|
7.8
|
(2.5)
|
18.2
|
|
Net Income (Loss) |
|
(764.2)
|
519.6
|
242.8
|
1,581.6
|
|
Balance Sheet Information |
|
|
|
|
|
|
Total Property, Plant and Equipment |
|
60,599.8
|
|
60,599.8
|
|
$ 65,481.4
|
Accumulated Depreciation and Amortization |
|
16,337.6
|
|
16,337.6
|
|
19,348.2
|
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET |
|
44,262.2
|
|
44,262.2
|
|
46,133.2
|
Assets Held for Sale |
|
1,915.3
|
|
1,915.3
|
|
|
Total Assets |
|
61,442.0
|
|
61,442.0
|
|
61,683.1
|
Long-term Debt Due Within One Year |
|
2,384.8
|
|
2,384.8
|
|
1,831.8
|
Long-term Debt - Affiliated |
|
0.0
|
|
0.0
|
|
0.0
|
Long-term Debt |
|
17,319.9
|
|
17,319.9
|
|
17,740.9
|
Total Long-term Debt Outstanding |
|
19,704.7
|
|
19,704.7
|
|
19,572.7
|
Liabilities Held for Sale |
|
231.0
|
|
231.0
|
|
|
Vertically Integrated Utilities [Member] |
|
|
|
|
|
|
Reportable Segment Information |
|
|
|
|
|
|
Sales Revenue, Net |
|
2,538.3
|
2,435.8
|
6,864.6
|
7,081.8
|
|
Revenues |
|
2,556.3
|
2,471.5
|
6,927.8
|
7,159.1
|
|
Income (Loss) from Continuing Operations |
|
343.4
|
274.5
|
832.6
|
782.7
|
|
Income (Loss) from Discontinued Operations, Net of Tax |
|
0.0
|
0.0
|
0.0
|
0.0
|
|
Net Income (Loss) |
|
343.4
|
274.5
|
832.6
|
782.7
|
|
Balance Sheet Information |
|
|
|
|
|
|
Total Property, Plant and Equipment |
|
41,015.6
|
|
41,015.6
|
|
40,130.3
|
Accumulated Depreciation and Amortization |
|
12,549.8
|
|
12,549.8
|
|
12,335.0
|
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET |
|
28,465.8
|
|
28,465.8
|
|
27,795.3
|
Assets Held for Sale |
|
0.0
|
|
0.0
|
|
|
Total Assets |
|
36,924.3
|
|
36,924.3
|
|
35,792.3
|
Long-term Debt Due Within One Year |
|
1,611.0
|
|
1,611.0
|
|
935.4
|
Long-term Debt - Affiliated |
|
20.0
|
|
20.0
|
|
20.0
|
Long-term Debt |
|
10,067.3
|
|
10,067.3
|
|
9,833.0
|
Total Long-term Debt Outstanding |
|
11,698.3
|
|
11,698.3
|
|
10,788.4
|
Liabilities Held for Sale |
|
0.0
|
|
0.0
|
|
|
Transmission And Distribution Utilities [Member] |
|
|
|
|
|
|
Reportable Segment Information |
|
|
|
|
|
|
Sales Revenue, Net |
|
1,245.4
|
1,163.6
|
3,398.9
|
3,377.9
|
|
Revenues |
|
1,275.6
|
1,188.6
|
3,468.5
|
3,519.4
|
|
Income (Loss) from Continuing Operations |
|
155.5
|
113.0
|
388.1
|
287.8
|
|
Income (Loss) from Discontinued Operations, Net of Tax |
|
0.0
|
0.0
|
0.0
|
0.0
|
|
Net Income (Loss) |
|
155.5
|
113.0
|
388.1
|
287.8
|
|
Balance Sheet Information |
|
|
|
|
|
|
Total Property, Plant and Equipment |
|
14,438.4
|
|
14,438.4
|
|
13,840.5
|
Accumulated Depreciation and Amortization |
|
3,647.4
|
|
3,647.4
|
|
3,529.2
|
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET |
|
10,791.0
|
|
10,791.0
|
|
10,311.3
|
Assets Held for Sale |
|
0.0
|
|
0.0
|
|
|
Total Assets |
|
14,155.7
|
|
14,155.7
|
|
14,640.2
|
Long-term Debt Due Within One Year |
|
268.3
|
|
268.3
|
|
824.7
|
Long-term Debt - Affiliated |
|
0.0
|
|
0.0
|
|
0.0
|
Long-term Debt |
|
4,745.3
|
|
4,745.3
|
|
4,776.8
|
Total Long-term Debt Outstanding |
|
5,013.6
|
|
5,013.6
|
|
5,601.5
|
Liabilities Held for Sale |
|
0.0
|
|
0.0
|
|
|
AEP Transmission Holdco [Member] |
|
|
|
|
|
|
Reportable Segment Information |
|
|
|
|
|
|
Sales Revenue, Net |
|
39.5
|
26.9
|
110.1
|
74.1
|
|
Revenues |
|
132.4
|
87.5
|
382.7
|
244.9
|
|
Income (Loss) from Continuing Operations |
|
69.5
|
45.9
|
209.5
|
147.7
|
|
Income (Loss) from Discontinued Operations, Net of Tax |
|
0.0
|
0.0
|
0.0
|
0.0
|
|
Net Income (Loss) |
|
69.5
|
45.9
|
209.5
|
147.7
|
|
Balance Sheet Information |
|
|
|
|
|
|
Total Property, Plant and Equipment |
|
4,896.4
|
|
4,896.4
|
|
3,977.6
|
Accumulated Depreciation and Amortization |
|
88.2
|
|
88.2
|
|
52.3
|
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET |
|
4,808.2
|
|
4,808.2
|
|
3,925.3
|
Assets Held for Sale |
|
0.0
|
|
0.0
|
|
|
Total Assets |
|
5,780.5
|
|
5,780.5
|
|
5,012.1
|
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 |
|
1,660.4
|
|
1,660.4
|
|
1,648.4
|
Total Long-term Debt Outstanding |
|
1,660.4
|
|
1,660.4
|
|
1,648.4
|
Liabilities Held for Sale |
|
0.0
|
|
0.0
|
|
|
Generation And Marketing [Member] |
|
|
|
|
|
|
Reportable Segment Information |
|
|
|
|
|
|
Sales Revenue, Net |
|
823.3
|
801.8
|
2,192.5
|
2,288.6
|
|
Revenues |
|
859.4
|
836.0
|
2,291.2
|
2,806.7
|
|
Income (Loss) from Continuing Operations |
|
(1,369.2)
|
91.6
|
(1,248.8)
|
360.3
|
|
Income (Loss) from Discontinued Operations, Net of Tax |
|
0.0
|
0.0
|
0.0
|
0.0
|
|
Net Income (Loss) |
|
(1,369.2)
|
91.6
|
(1,248.8)
|
360.3
|
|
Balance Sheet Information |
|
|
|
|
|
|
Total Property, Plant and Equipment |
|
234.3
|
|
234.3
|
|
7,461.3
|
Accumulated Depreciation and Amortization |
|
44.2
|
|
44.2
|
|
3,367.0
|
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET |
|
190.1
|
|
190.1
|
|
4,094.3
|
Assets Held for Sale |
|
1,915.3
|
|
1,915.3
|
|
|
Total Assets |
|
3,176.6
|
|
3,176.6
|
|
5,414.5
|
Long-term Debt Due Within One Year |
|
505.2
|
|
505.2
|
|
71.6
|
Long-term Debt - Affiliated |
|
32.2
|
|
32.2
|
|
32.2
|
Long-term Debt |
|
0.0
|
|
0.0
|
|
639.5
|
Total Long-term Debt Outstanding |
|
537.4
|
|
537.4
|
|
743.3
|
Liabilities Held for Sale |
|
231.0
|
|
231.0
|
|
|
All Other [Member] |
|
|
|
|
|
|
Reportable Segment Information |
|
|
|
|
|
|
Sales Revenue, Net |
[1] |
5.7
|
3.3
|
23.9
|
16.1
|
|
Revenues |
[1] |
24.8
|
23.8
|
79.1
|
73.9
|
|
Income (Loss) from Continuing Operations |
[1] |
36.6
|
(13.2)
|
63.9
|
(15.1)
|
|
Income (Loss) from Discontinued Operations, Net of Tax |
[1] |
0.0
|
7.8
|
(2.5)
|
18.2
|
|
Net Income (Loss) |
[1] |
36.6
|
(5.4)
|
61.4
|
3.1
|
|
Balance Sheet Information |
|
|
|
|
|
|
Total Property, Plant and Equipment |
[1] |
368.6
|
|
368.6
|
|
350.9
|
Accumulated Depreciation and Amortization |
[1] |
192.1
|
|
192.1
|
|
176.9
|
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET |
[1] |
176.5
|
|
176.5
|
|
174.0
|
Assets Held for Sale |
|
0.0
|
|
0.0
|
|
|
Total Assets |
[1] |
21,772.4
|
|
21,772.4
|
|
21,907.4
|
Long-term Debt Due Within One Year |
[1] |
0.3
|
|
0.3
|
|
0.1
|
Long-term Debt - Affiliated |
[1] |
0.0
|
|
0.0
|
|
0.0
|
Long-term Debt |
[1] |
846.9
|
|
846.9
|
|
843.2
|
Total Long-term Debt Outstanding |
[1] |
847.2
|
|
847.2
|
|
843.3
|
Liabilities Held for Sale |
|
0.0
|
|
0.0
|
|
|
Segment Reconciling Items [Member] |
|
|
|
|
|
|
Reportable Segment Information |
|
|
|
|
|
|
Sales Revenue, Net |
|
(196.3)
|
(176.0)
|
(559.3)
|
(965.5)
|
|
Segment Reconciling Items [Member] | Vertically Integrated Utilities [Member] |
|
|
|
|
|
|
Reportable Segment Information |
|
|
|
|
|
|
Sales Revenue, Net |
|
18.0
|
35.7
|
63.2
|
77.3
|
|
Segment Reconciling Items [Member] | Transmission And Distribution Utilities [Member] |
|
|
|
|
|
|
Reportable Segment Information |
|
|
|
|
|
|
Sales Revenue, Net |
|
30.2
|
25.0
|
69.6
|
141.5
|
|
Segment Reconciling Items [Member] | AEP Transmission Holdco [Member] |
|
|
|
|
|
|
Reportable Segment Information |
|
|
|
|
|
|
Sales Revenue, Net |
|
92.9
|
60.6
|
272.6
|
170.8
|
|
Segment Reconciling Items [Member] | Generation And Marketing [Member] |
|
|
|
|
|
|
Reportable Segment Information |
|
|
|
|
|
|
Sales Revenue, Net |
|
36.1
|
34.2
|
98.7
|
518.1
|
|
Segment Reconciling Items [Member] | All Other [Member] |
|
|
|
|
|
|
Reportable Segment Information |
|
|
|
|
|
|
Sales Revenue, Net |
[1] |
19.1
|
20.5
|
55.2
|
57.8
|
|
Consolidation, Eliminations [Member] |
|
|
|
|
|
|
Reportable Segment Information |
|
|
|
|
|
|
Sales Revenue, Net |
|
0.0
|
0.0
|
0.0
|
0.0
|
|
Revenues |
|
(196.3)
|
(176.0)
|
(559.3)
|
(965.5)
|
|
Income (Loss) from Continuing Operations |
|
0.0
|
0.0
|
0.0
|
0.0
|
|
Income (Loss) from Discontinued Operations, Net of Tax |
|
0.0
|
0.0
|
0.0
|
0.0
|
|
Net Income (Loss) |
|
0.0
|
$ 0.0
|
0.0
|
$ 0.0
|
|
Balance Sheet Information |
|
|
|
|
|
|
Total Property, Plant and Equipment |
[2] |
(353.5)
|
|
(353.5)
|
|
(279.2)
|
Accumulated Depreciation and Amortization |
[2] |
(184.1)
|
|
(184.1)
|
|
(112.2)
|
TOTAL PROPERTY, PLANT AND EQUIPMENT - NET |
[2] |
(169.4)
|
|
(169.4)
|
|
(167.0)
|
Assets Held for Sale |
|
0.0
|
|
0.0
|
|
|
Total Assets |
[2],[3] |
(20,367.5)
|
|
(20,367.5)
|
|
(21,083.4)
|
Long-term Debt Due Within One Year |
|
0.0
|
|
0.0
|
|
0.0
|
Long-term Debt - Affiliated |
|
(52.2)
|
|
(52.2)
|
|
(52.2)
|
Long-term Debt |
|
0.0
|
|
0.0
|
|
0.0
|
Total Long-term Debt Outstanding |
|
(52.2)
|
|
(52.2)
|
|
$ (52.2)
|
Liabilities Held for Sale |
|
$ 0.0
|
|
$ 0.0
|
|
|
|
|