Leases - Lessee (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
Lease Cost [Abstract]
Operating lease cost	$ 6	$ 21
Short-term lease cost	2	5
Total lease cost	$ 8	26
Operating cash flows from operating leases		21
Right-of-use asset obtained in exchange for new operating lease liabilities		$ 37
Weighted-average remaining lease term (in years)	8 years	8 years
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2019	$ 8	$ 8
2020	27	27
2021	21	21
2022	16	16
2023	14	14
2024	12	12
Thereafter	25	25
Total	$ 123	$ 123
2019				$ 26
2020				21
2021				15
2022				13
2023				8
Thereafter				33
Total				116
Assets and Liabilities, Lessee [Abstract]
Weighted-average discount rate	3.47%	3.47%
Current lease liabilities	$ 25	$ 25	$ 23
Non-current lease liabilities	80	80	67
Right-of-use assets	97	97	81
LG And E And KU Energy LLC [Member]
Lease Cost [Abstract]
Operating lease cost	5	17
Short-term lease cost	1	2
Total lease cost	$ 6	19
Operating cash flows from operating leases		17
Right-of-use asset obtained in exchange for new operating lease liabilities		$ 8
Weighted-average remaining lease term (in years)	5 years	5 years
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2019	$ 5	$ 5
2020	16	16
2021	12	12
2022	8	8
2023	7	7
2024	6	6
Thereafter	7	7
Total	$ 61	$ 61
2019				20
2020				15
2021				11
2022				7
2023				6
Thereafter				11
Total				70
Assets and Liabilities, Lessee [Abstract]
Weighted-average discount rate	3.97%	3.97%
Current lease liabilities	$ 16	$ 16	18
Non-current lease liabilities	39	39	46
Right-of-use assets	$ 47	$ 47	56
LG And E And KU Energy LLC [Member] | Minimum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Renewal Term	1 year	1 year
LG And E And KU Energy LLC [Member] | Maximum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Renewal Term	10 years	10 years
Louisville Gas And Electric Co [Member]
Lease Cost [Abstract]
Operating lease cost	$ 1	$ 7
Short-term lease cost	0	1
Total lease cost	$ 1	8
Operating cash flows from operating leases		8
Right-of-use asset obtained in exchange for new operating lease liabilities		$ 3
Weighted-average remaining lease term (in years)	5 years	5 years
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2019	$ 2	$ 2
2020	6	6
2021	5	5
2022	3	3
2023	3	3
2024	3	3
Thereafter	3	3
Total	$ 25	$ 25
2019				10
2020				6
2021				4
2022				3
2023				3
Thereafter				4
Total				30
Assets and Liabilities, Lessee [Abstract]
Weighted-average discount rate	3.90%	3.90%
Current lease liabilities	$ 6	$ 6	9
Non-current lease liabilities	16	16	18
Right-of-use assets	$ 19	$ 19	23
Louisville Gas And Electric Co [Member] | Minimum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Renewal Term	1 year	1 year
Louisville Gas And Electric Co [Member] | Maximum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Renewal Term	10 years	10 years
Kentucky Utilities Co [Member]
Lease Cost [Abstract]
Operating lease cost	$ 3	$ 9
Short-term lease cost	1	1
Total lease cost	$ 4	10
Operating cash flows from operating leases		9
Right-of-use asset obtained in exchange for new operating lease liabilities		$ 5
Weighted-average remaining lease term (in years)	5 years	5 years
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2019	$ 3	$ 3
2020	10	10
2021	7	7
2022	5	5
2023	3	3
2024	3	3
Thereafter	3	3
Total	$ 34	$ 34
2019				10
2020				9
2021				7
2022				4
2023				3
Thereafter				6
Total				$ 39
Assets and Liabilities, Lessee [Abstract]
Weighted-average discount rate	4.01%	4.01%
Current lease liabilities	$ 9	$ 9	9
Non-current lease liabilities	22	22	26
Right-of-use assets	$ 27	$ 27	$ 31
Kentucky Utilities Co [Member] | Minimum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Renewal Term	1 year	1 year
Kentucky Utilities Co [Member] | Maximum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Renewal Term	10 years	10 years