Leases - Lessee (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
Lease Cost [Abstract]
Operating lease cost	$ 7	$ 14
Short-term lease cost	2	2
Total lease cost	$ 9	16
Operating cash flows from operating leases		14
Right-of-use asset obtained in exchange for new operating lease liabilities		$ 7
Weighted-average remaining lease term (in years)	9 years	9 years
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2019	$ 20	$ 20
2020	19	19
2021	14	14
2022	9	9
2023	8	8
2024	7	7
Thereafter	22	22
Total	$ 99	$ 99
2019				$ 26
2020				21
2021				15
2022				13
2023				8
Thereafter				33
Total				116
Assets and Liabilities, Lessee [Abstract]
Weighted-average discount rate	3.77%	3.77%
Current lease liabilities	$ 20	$ 20	$ 23
Non-current lease liabilities	62	62	67
Right-of-use assets	74	74	81
LG And E And KU Energy LLC [Member]
Lease Cost [Abstract]
Operating lease cost	5	12
Short-term lease cost	1	1
Total lease cost	$ 6	13
Operating cash flows from operating leases		12
Right-of-use asset obtained in exchange for new operating lease liabilities		$ 6
Weighted-average remaining lease term (in years)	5 years	5 years
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2019	$ 18	$ 18
2020	14	14
2021	10	10
2022	7	7
2023	6	6
2024	5	5
Thereafter	4	4
Total	$ 64	$ 64
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	42	42	46
Right-of-use assets	$ 50	$ 50	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	$ 2	$ 6
Short-term lease cost	1	1
Total lease cost	$ 3	7
Operating cash flows from operating leases		6
Right-of-use asset obtained in exchange for new operating lease liabilities		$ 2
Weighted-average remaining lease term (in years)	5 years	5 years
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2019	$ 7	$ 7
2020	5	5
2021	4	4
2022	3	3
2023	2	2
2024	2	2
Thereafter	1	1
Total	$ 24	$ 24
2019				10
2020				6
2021				4
2022				3
2023				3
Thereafter				4
Total				30
Assets and Liabilities, Lessee [Abstract]
Weighted-average discount rate	3.89%	3.89%
Current lease liabilities	$ 6	$ 6	9
Non-current lease liabilities	17	17	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	$ 6
Short-term lease cost	0	0
Total lease cost	$ 3	6
Operating cash flows from operating leases		6
Right-of-use asset obtained in exchange for new operating lease liabilities		$ 4
Weighted-average remaining lease term (in years)	5 years	5 years
Lessee, Operating Lease, Liability, Payment, Due [Abstract]
2019	$ 10	$ 10
2020	8	8
2021	6	6
2022	4	4
2023	3	3
2024	3	3
Thereafter	2	2
Total	$ 36	$ 36
2019				10
2020				9
2021				7
2022				4
2023				3
Thereafter				6
Total				$ 39
Assets and Liabilities, Lessee [Abstract]
Weighted-average discount rate	4.02%	4.02%
Current lease liabilities	$ 9	$ 9	9
Non-current lease liabilities	24	24	26
Right-of-use assets	$ 29	$ 29	$ 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