Jointly Owned Facilities (Details) (USD $) In Millions, unless otherwise specified
|
12 Months Ended |
Dec. 31, 2012
|
Dec. 31, 2011
|
Jointly Owned Facilities [Line Items] |
|
|
Percentage of leasehold interest in Colstrip Units 1 and 2 |
50.00% |
50.00% |
Percentage of leasehold interest in Colstrip Unit 3 |
30.00% |
30.00% |
Percentage of interest by Northwestern in Colstrip Unit 4 |
30.00% |
30.00% |
Proportionate share by each party of operating and construction costs regarding Colstrip Unit 3 or 4 |
15.00% |
15.00% |
Susquehanna Nuclear Generation Plant [Member]
|
|
|
Jointly Owned Facilities [Line Items] |
|
|
Ownership interest |
90.00% |
90.00% |
Electric plant |
4,628 |
4,608 |
Accumulated depreciation |
3,530 |
3,496 |
Construction work in progress |
65 |
42 |
Conemaugh Generation Plant [Member]
|
|
|
Jointly Owned Facilities [Line Items] |
|
|
Ownership interest |
16.25% |
16.25% |
Electric plant |
238 |
233 |
Accumulated depreciation |
122 |
115 |
Construction work in progress |
30 |
14 |
Keystone Generation Plant [Member]
|
|
|
Jointly Owned Facilities [Line Items] |
|
|
Ownership interest |
12.34% |
12.34% |
Electric plant |
206 |
198 |
Accumulated depreciation |
82 |
69 |
Construction work in progress |
3 |
3 |
Trimble County-Units 1 and 2 Generation Plant [Member]
|
|
|
Jointly Owned Facilities [Line Items] |
|
|
Ownership interest |
75.00% |
75.00% |
Electric plant |
1,279 |
1,245 |
Accumulated depreciation |
112 |
61 |
Construction work in progress |
43 |
35 |
Merrill Creek Reservoir [Member]
|
|
|
Jointly Owned Facilities [Line Items] |
|
|
Ownership interest |
8.37% |
8.37% |
Other property |
22 |
22 |
Accumulated depreciation |
15 |
15 |
PPL Energy Supply LLC [Member]
|
|
|
Jointly Owned Facilities [Line Items] |
|
|
Percentage of leasehold interest in Colstrip Units 1 and 2 |
50.00% |
50.00% |
Percentage of leasehold interest in Colstrip Unit 3 |
30.00% |
30.00% |
Percentage of interest by Northwestern in Colstrip Unit 4 |
30.00% |
30.00% |
Proportionate share by each party of operating and construction costs regarding Colstrip Unit 3 or 4 |
15.00% |
15.00% |
PPL Energy Supply LLC [Member] | Susquehanna Nuclear Generation Plant [Member]
|
|
|
Jointly Owned Facilities [Line Items] |
|
|
Ownership interest |
90.00% |
90.00% |
Electric plant |
4,628 |
4,608 |
Accumulated depreciation |
3,530 |
3,496 |
Construction work in progress |
65 |
42 |
PPL Energy Supply LLC [Member] | Conemaugh Generation Plant [Member]
|
|
|
Jointly Owned Facilities [Line Items] |
|
|
Ownership interest |
16.25% |
16.25% |
Electric plant |
238 |
233 |
Accumulated depreciation |
122 |
115 |
Construction work in progress |
30 |
14 |
PPL Energy Supply LLC [Member] | Keystone Generation Plant [Member]
|
|
|
Jointly Owned Facilities [Line Items] |
|
|
Ownership interest |
12.34% |
12.34% |
Electric plant |
206 |
198 |
Accumulated depreciation |
82 |
69 |
Construction work in progress |
3 |
3 |
PPL Energy Supply LLC [Member] | Merrill Creek Reservoir [Member]
|
|
|
Jointly Owned Facilities [Line Items] |
|
|
Ownership interest |
8.37% |
8.37% |
Other property |
22 |
22 |
Accumulated depreciation |
15 |
15 |
LG And E And KU Energy LLC [Member] | Trimble County Unit 1 [Member]
|
|
|
Jointly Owned Facilities [Line Items] |
|
|
Ownership interest |
75.00% |
75.00% |
Electric plant |
304 |
297 |
Other property |
|
|
Accumulated depreciation |
33 |
19 |
Construction work in progress |
10 |
11 |
LG And E And KU Energy LLC [Member] | Trimble County Unit 2 [Member]
|
|
|
Jointly Owned Facilities [Line Items] |
|
|
Ownership interest |
75.00% |
75.00% |
Electric plant |
975 |
948 |
Other property |
|
|
Accumulated depreciation |
79 |
42 |
Construction work in progress |
33 |
24 |
Louisville Gas And Electric Co [Member] | E W Brown Units 6 And 7 [Member]
|
|
|
Jointly Owned Facilities [Line Items] |
|
|
Ownership interest |
38.00% |
38.00% |
Electric plant |
40 |
39 |
Other property |
|
|
Accumulated depreciation |
5 |
3 |
Construction work in progress |
|
|
Louisville Gas And Electric Co [Member] | Paddys Run Unit 13 And E W Brown Unit 5 [Member]
|
|
|
Jointly Owned Facilities [Line Items] |
|
|
Ownership interest |
53.00% |
53.00% |
Electric plant |
46 |
44 |
Other property |
|
|
Accumulated depreciation |
3 |
2 |
Construction work in progress |
|
5 |
Louisville Gas And Electric Co [Member] | Trimble County Unit 1 [Member]
|
|
|
Jointly Owned Facilities [Line Items] |
|
|
Ownership interest |
75.00% |
75.00% |
Electric plant |
304 |
297 |
Other property |
|
|
Accumulated depreciation |
33 |
19 |
Construction work in progress |
10 |
11 |
Louisville Gas And Electric Co [Member] | Trimble County Unit 2 [Member]
|
|
|
Jointly Owned Facilities [Line Items] |
|
|
Ownership interest |
14.25% |
14.25% |
Electric plant |
198 |
190 |
Other property |
|
|
Accumulated depreciation |
14 |
7 |
Construction work in progress |
13 |
7 |
Louisville Gas And Electric Co [Member] | Trimble County Units 5 And 6 [Member]
|
|
|
Jointly Owned Facilities [Line Items] |
|
|
Ownership interest |
29.00% |
29.00% |
Electric plant |
29 |
31 |
Other property |
|
|
Accumulated depreciation |
2 |
1 |
Construction work in progress |
|
|
Louisville Gas And Electric Co [Member] | Trimble County Units 7 Through 10 [Member]
|
|
|
Jointly Owned Facilities [Line Items] |
|
|
Ownership interest |
37.00% |
37.00% |
Electric plant |
68 |
64 |
Other property |
|
|
Accumulated depreciation |
6 |
4 |
Construction work in progress |
2 |
1 |
Louisville Gas And Electric Co [Member] | Cane Run Unit 7 Combined Cycle Gas Turbine [Member]
|
|
|
Jointly Owned Facilities [Line Items] |
|
|
Ownership interest |
22.00% |
|
Electric plant |
|
|
Other property |
|
|
Accumulated depreciation |
|
|
Construction work in progress |
16 |
|
Kentucky Utilities Co [Member] | E W Brown Units 6 And 7 [Member]
|
|
|
Jointly Owned Facilities [Line Items] |
|
|
Ownership interest |
62.00% |
62.00% |
Electric plant |
64 |
64 |
Other property |
|
|
Accumulated depreciation |
7 |
5 |
Construction work in progress |
1 |
|
Kentucky Utilities Co [Member] | Paddys Run Unit 13 And E W Brown Unit 5 [Member]
|
|
|
Jointly Owned Facilities [Line Items] |
|
|
Ownership interest |
47.00% |
47.00% |
Electric plant |
42 |
39 |
Other property |
|
|
Accumulated depreciation |
2 |
2 |
Construction work in progress |
|
4 |
Kentucky Utilities Co [Member] | Trimble County Unit 2 [Member]
|
|
|
Jointly Owned Facilities [Line Items] |
|
|
Ownership interest |
60.75% |
60.75% |
Electric plant |
777 |
758 |
Other property |
|
|
Accumulated depreciation |
65 |
35 |
Construction work in progress |
20 |
17 |
Kentucky Utilities Co [Member] | Trimble County Units 5 And 6 [Member]
|
|
|
Jointly Owned Facilities [Line Items] |
|
|
Ownership interest |
71.00% |
71.00% |
Electric plant |
70 |
66 |
Other property |
|
|
Accumulated depreciation |
4 |
2 |
Construction work in progress |
|
4 |
Kentucky Utilities Co [Member] | Trimble County Units 7 Through 10 [Member]
|
|
|
Jointly Owned Facilities [Line Items] |
|
|
Ownership interest |
63.00% |
63.00% |
Electric plant |
116 |
109 |
Other property |
|
|
Accumulated depreciation |
10 |
6 |
Construction work in progress |
2 |
5 |
Kentucky Utilities Co [Member] | Cane Run Unit 7 Combined Cycle Gas Turbine [Member]
|
|
|
Jointly Owned Facilities [Line Items] |
|
|
Ownership interest |
78.00% |
|
Electric plant |
|
|
Other property |
|
|
Accumulated depreciation |
|
|
Construction work in progress |
53 |
|