Leases - Lessee (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2026	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Lease, Cost [Abstract]
Operating lease cost	$ 30	$ 33
Short-term lease cost	9	7
Total lease cost	39	40
Operating cash flows from operating leases	26	29
Right-of-use asset obtained in exchange for new operating lease liabilities	17	46
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2020								$ 27
2021							$ 22
2022						$ 18
2023					$ 15
2024				$ 8
Thereafter			$ 20
Total	$ 110
Assets and Liabilities, Lessee [Abstract]
Weighted-average discount rate	3.35%
Weighted-average remaining lease term (in years)	8 years
Other Current Liabilities [Member]
Assets and Liabilities, Lessee [Abstract]
Current lease liabilities	$ 24
Other Deferred Credits And Noncurrent Liabilities [Member]
Assets and Liabilities, Lessee [Abstract]
Non-current lease liabilities	70
Other Noncurrent Assets [Member]
Assets and Liabilities, Lessee [Abstract]
Right-of-use assets	87
LG And E And KU Energy LLC [Member]
Lease, Cost [Abstract]
Operating lease cost	22	25
Short-term lease cost	2	2
Total lease cost	24	27
Operating cash flows from operating leases	18	21
Right-of-use asset obtained in exchange for new operating lease liabilities	16	16
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2020								17
2021							13
2022						10
2023					8
2024				6
Thereafter			3
Total	$ 57
Assets and Liabilities, Lessee [Abstract]
Weighted-average discount rate	3.66%
Weighted-average remaining lease term (in years)	4 years
LG And E And KU Energy LLC [Member] | Minimum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Renewal Term	1 year
LG And E And KU Energy LLC [Member] | Maximum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Renewal Term	10 years
LG And E And KU Energy LLC [Member] | Other Current Liabilities [Member]
Assets and Liabilities, Lessee [Abstract]
Current lease liabilities	$ 16
LG And E And KU Energy LLC [Member] | Other Deferred Credits And Noncurrent Liabilities [Member]
Assets and Liabilities, Lessee [Abstract]
Non-current lease liabilities	37
LG And E And KU Energy LLC [Member] | Other Noncurrent Assets [Member]
Assets and Liabilities, Lessee [Abstract]
Right-of-use assets	46
Louisville Gas And Electric Co [Member]
Lease, Cost [Abstract]
Operating lease cost	8	12
Short-term lease cost	1	1
Total lease cost	9	13
Operating cash flows from operating leases	7	9
Right-of-use asset obtained in exchange for new operating lease liabilities	6	5
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2020								6
2021							5
2022						4
2023					3
2024				3
Thereafter			1
Total	$ 22
Assets and Liabilities, Lessee [Abstract]
Weighted-average discount rate	3.53%
Weighted-average remaining lease term (in years)	4 years
Louisville Gas And Electric Co [Member] | Minimum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Renewal Term	1 year
Louisville Gas And Electric Co [Member] | Maximum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Renewal Term	10 years
Louisville Gas And Electric Co [Member] | Other Current Liabilities [Member]
Assets and Liabilities, Lessee [Abstract]
Current lease liabilities	$ 6
Louisville Gas And Electric Co [Member] | Other Deferred Credits And Noncurrent Liabilities [Member]
Assets and Liabilities, Lessee [Abstract]
Non-current lease liabilities	15
Louisville Gas And Electric Co [Member] | Other Noncurrent Assets [Member]
Assets and Liabilities, Lessee [Abstract]
Right-of-use assets	17
Kentucky Utilities Co [Member]
Lease, Cost [Abstract]
Operating lease cost	13	13
Short-term lease cost	1	1
Total lease cost	14	14
Operating cash flows from operating leases	11	11
Right-of-use asset obtained in exchange for new operating lease liabilities	9	$ 11
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2020								$ 10
2021							$ 8
2022						$ 6
2023					$ 4
2024				$ 3
Thereafter			$ 2
Total	$ 33
Assets and Liabilities, Lessee [Abstract]
Weighted-average discount rate	3.68%
Weighted-average remaining lease term (in years)	4 years
Kentucky Utilities Co [Member] | Minimum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Renewal Term	1 year
Kentucky Utilities Co [Member] | Maximum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Renewal Term	10 years
Kentucky Utilities Co [Member] | Other Current Liabilities [Member]
Assets and Liabilities, Lessee [Abstract]
Current lease liabilities	$ 9
Kentucky Utilities Co [Member] | Other Deferred Credits And Noncurrent Liabilities [Member]
Assets and Liabilities, Lessee [Abstract]
Non-current lease liabilities	21
Kentucky Utilities Co [Member] | Other Noncurrent Assets [Member]
Assets and Liabilities, Lessee [Abstract]
Right-of-use assets	$ 27