Jointly Owned Facilities (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Trimble County Unit 1 [Member]
Jointly Owned Facilities [Line Items]
Ownership interest	75.00%	75.00%
Electric plant	$ 440	$ 440
Accumulated depreciation	64	54
Construction work in progress	$ 2	$ 2
Trimble County Unit 2 [Member]
Jointly Owned Facilities [Line Items]
Ownership interest	75.00%	75.00%
Electric plant	$ 1,340	$ 1,278
Accumulated depreciation	227	203
Construction work in progress	$ 106	$ 134
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	$ 440	$ 440
Accumulated depreciation	64	54
Construction work in progress	$ 2	$ 2
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	$ 1,340	$ 1,278
Accumulated depreciation	227	203
Construction work in progress	$ 106	$ 134
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	$ 46	$ 45
Accumulated depreciation	22	20
Construction work in progress	$ 0	$ 0
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	$ 51	$ 52
Accumulated depreciation	22	20
Construction work in progress	$ 0	$ 0
Louisville Gas And Electric Co [Member] | Trimble County Unit 1 [Member]
Jointly Owned Facilities [Line Items]
Ownership interest	75.00%	75.00%
Electric plant	$ 440	$ 440
Accumulated depreciation	64	54
Construction work in progress	$ 2	$ 2
Louisville Gas And Electric Co [Member] | Trimble County Unit 2 [Member]
Jointly Owned Facilities [Line Items]
Ownership interest	14.25%	14.25%
Electric plant	$ 370	$ 340
Accumulated depreciation	51	43
Construction work in progress	$ 54	$ 69
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	$ 33	$ 32
Accumulated depreciation	14	12
Construction work in progress	$ 1	$ 0
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	$ 77	$ 78
Accumulated depreciation	31	27
Construction work in progress	$ 1	$ 0
Louisville Gas And Electric Co [Member] | Cane Run Unit 7 [Member]
Jointly Owned Facilities [Line Items]
Ownership interest	22.00%	22.00%
Electric plant	$ 123	$ 119
Accumulated depreciation	15	13
Construction work in progress	$ 0	$ 0
Louisville Gas And Electric Co [Member] | E W Brown Solar Unit [Member]
Jointly Owned Facilities [Line Items]
Ownership interest	39.00%	39.00%
Electric plant	$ 10	$ 10
Accumulated depreciation	2	2
Construction work in progress	$ 0	$ 0
Louisville Gas And Electric Co [Member] | Jointly Owned Solar Share [Member]
Jointly Owned Facilities [Line Items]
Ownership interest	44.00%	44.00%
Electric plant	$ 2	$ 1
Accumulated depreciation	0	0
Construction work in progress	$ 0	$ 0
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	$ 76	$ 75
Accumulated depreciation	37	32
Construction work in progress	$ 0	$ 0
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	$ 45	$ 46
Accumulated depreciation	20	14
Construction work in progress	$ 0	$ 0
Kentucky Utilities Co [Member] | Trimble County Unit 2 [Member]
Jointly Owned Facilities [Line Items]
Ownership interest	60.75%	60.75%
Electric plant	$ 970	$ 938
Accumulated depreciation	176	160
Construction work in progress	$ 52	$ 65
Kentucky Utilities Co [Member] | Trimble County Units 5 And 6 [Member]
Jointly Owned Facilities [Line Items]
Ownership interest	71.00%	71.00%
Electric plant	$ 77	$ 76
Accumulated depreciation	33	29
Construction work in progress	$ 4	$ 0
Kentucky Utilities Co [Member] | Trimble County Units 7 Through 10 [Member]
Jointly Owned Facilities [Line Items]
Ownership interest	63.00%	63.00%
Electric plant	$ 129	$ 128
Accumulated depreciation	53	46
Construction work in progress	$ 2	$ 0
Kentucky Utilities Co [Member] | Cane Run Unit 7 [Member]
Jointly Owned Facilities [Line Items]
Ownership interest	78.00%	78.00%
Electric plant	$ 443	$ 429
Accumulated depreciation	57	49
Construction work in progress	$ 2	$ 1
Kentucky Utilities Co [Member] | E W Brown Solar Unit [Member]
Jointly Owned Facilities [Line Items]
Ownership interest	61.00%	61.00%
Electric plant	$ 16	$ 16
Accumulated depreciation	3	2
Construction work in progress	$ 0	$ 0
Kentucky Utilities Co [Member] | Jointly Owned Solar Share [Member]
Jointly Owned Facilities [Line Items]
Ownership interest	56.00%	56.00%
Electric plant	$ 2	$ 2
Accumulated depreciation	0	0
Construction work in progress	$ 0	$ 0