Jointly Owned Facilities (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Trimble County Unit 1 [Member]
Jointly Owned Facilities [Line Items]
Ownership interest	75.00%	75.00%
Electric plant	$ 440	$ 427
Accumulated depreciation	54	77
Construction work in progress	$ 2	$ 0
Trimble County Unit 2 [Member]
Jointly Owned Facilities [Line Items]
Ownership interest	75.00%	75.00%
Electric plant	$ 1,278	$ 1,063
Accumulated depreciation	203	199
Construction work in progress	$ 134	$ 293
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	$ 427
Accumulated depreciation	54	77
Construction work in progress	$ 2	$ 0
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	$ 1,278	$ 1,063
Accumulated depreciation	203	199
Construction work in progress	$ 134	$ 293
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	$ 45	$ 41
Accumulated depreciation	20	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	$ 52	$ 51
Accumulated depreciation	20	17
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	$ 427
Accumulated depreciation	54	77
Construction work in progress	$ 2	$ 0
Louisville Gas And Electric Co [Member] | Trimble County Unit 2 [Member]
Jointly Owned Facilities [Line Items]
Ownership interest	14.25%	14.25%
Electric plant	$ 340	$ 226
Accumulated depreciation	43	39
Construction work in progress	$ 69	$ 152
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	$ 32	$ 32
Accumulated depreciation	12	11
Construction work in progress	$ 0	$ 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	$ 78	$ 77
Accumulated depreciation	27	24
Construction work in progress	$ 0	$ 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	$ 119	$ 119
Accumulated depreciation	13	9
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	1
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%
Electric plant	$ 1
Accumulated depreciation	0
Construction work in progress	$ 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	$ 75	$ 66
Accumulated depreciation	32	31
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	$ 46	$ 46
Accumulated depreciation	14	15
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	$ 938	$ 837
Accumulated depreciation	160	160
Construction work in progress	$ 65	$ 141
Kentucky Utilities Co [Member] | Trimble County Units 5 And 6 [Member]
Jointly Owned Facilities [Line Items]
Ownership interest	71.00%	71.00%
Electric plant	$ 76	$ 76
Accumulated depreciation	29	25
Construction work in progress	$ 0	$ 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	$ 128	$ 129
Accumulated depreciation	46	41
Construction work in progress	$ 0	$ 0
Kentucky Utilities Co [Member] | Cane Run Unit 7 [Member]
Jointly Owned Facilities [Line Items]
Ownership interest	78.00%	78.00%
Electric plant	$ 429	$ 428
Accumulated depreciation	49	36
Construction work in progress	$ 1	$ 0
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	2	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%
Electric plant	$ 2
Accumulated depreciation	0
Construction work in progress	$ 0